10.14639/0392-100X-N2736
Objective. To translate and validate an Italian version of the Questionnaire of Olfactory Disorders (IT-QOD).Materials and methods. This is a prospective, multicentre study that involved patients with olfactory dysfunction (OD). Both cases and controls underwent administration of the IT-QOD, Sino-Nasal Outcome Test-22 (SNOT-22) and psychophysical evaluation of orthonasal and retronasal olfactory function. Results. The IT-QOD was administered to 96 patients and 38 controls. The Cronbach’s alpha exceeded 0.90, indicating satisfactory internal consistency. The test-retest reliability was found to be high for both parosmia (rs = 0.944) and life quality (rs = 0.969). Patients with OD had significantly higher IT-QOD scores compared to healthy individuals (p &lt; 0.001), indicating strong internal validity. The external validity was also satisfactory, as shown by the significant correlation with SNOT-22 (rs = -0.54) and the threshold, discrimination, and identification score (rs = -0.63). Conclusions. The IT-QOD was demonstrated to be reliable and valid to assess the impact of OD on the quality of life of Italian-speaking patients.
text/xml
1827-675X
2736
en
Paolo Boscolo-Rizzo
http://creativecommons.org/licenses/by-nc-nd/4.0
ACTA Otorhinolaryngologica Italica
otorhinolaryngology
Validity and reliability of the Questionnaire of Olfactory Disorders for Italian-speaking patients with olfactory dysfunction
Text.Serial.Journal
https://www.actaitalica.it/
44
Rhinology
2024-02-27
2023-08-29
2024-02-28
2024-02-28
42-51
1
Paolo Boscolo-Rizzo
2024/02/27
10.14639/0392-100X-N2736
42
Department of Medical, Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, Trieste, Italy
1827-675X
otorhinolaryngology
en
51
Validity and reliability of the Questionnaire of Olfactory Disorders for Italian-speaking patients with olfactory dysfunction
https://www.actaitalica.it/article/download/2736/1072
44
ACTA OTORHINOLARYNGOLOGICA ITALICA 2024;44:42-51; doi: 10.14639/0392-100X-N2736




Rhinology


Validity and reliability of the Questionnaire of Olfactory
Disorders for Italian-speaking patients with olfactory
dysfunction
Luigi Angelo Vaira1,2, Giancarlo Tirelli3, Davide Rizzo4, Francesco Uderzo3, Francesco Avanzini5, Franco Trabalzini6,
Nicoletta Rivelli7, Doris Burger8, Luca Calabrese5, Paolo Solla9, Francesco Bussu4, Miguel Mayo-Yáñez10,
Jerome R. Lechien11,12, Giacomo De Riu1, Paolo Boscolo-Rizzo3
1
 Maxillofacial Surgery Operative Unit, Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Italy; 2 PhD
School of Biomedical Sciences, Department of Biomedical Sciences, University of Sassari, Sassari, Italy; 3 Department of Medical,
Surgical and Health Sciences, Section of Otolaryngology, University of Trieste, Trieste, Italy; 4 Otorhinolaryngology Operative Unit,
Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Italy; 5 Department of Otolaryngology Head and
Neck Surgery, Hospital of Bolzano (SABES-ASDAA), Bolzano, Italy; 6 Department of Otorhinolaryngology, Head and Neck Surgery,
Meyer Children’s Hospital, Firenze, Italy; 7 Edizioni Erikson, Trento, Italy; 8 Goethe Institut, Padua, Italy; 9 Neurology Operative Unit,
Department of Medicine, Surgery and Pharmacy, University of Sassari, Sassari, Italy; 10 Otorhinolaryngology, Head and Neck
Surgery Department, Complexo Hospitalario Universitario A Coruña (CHUAC), A Coruña, Galicia, Spain; 11 Department of Anatomy
and Experimental Oncology, Mons School of Medicine, UMONS. Research Institute for Health Sciences and Technology, University
of Mons (UMons), Mons, Belgium; 12 Department of Otolaryngology-Head Neck Surgery, Elsan Polyclinic of Poitiers, Poitiers, France


SUMMARY
Objective. To translate and validate an Italian version of the Questionnaire of Olfactory
Disorders (IT-QOD).
Materials and methods. This is a prospective, multicentre study that involved patients
with olfactory dysfunction (OD). Both cases and controls underwent administration of the
IT-QOD, Sino-Nasal Outcome Test-22 (SNOT-22) and psychophysical evaluation of ortho-
nasal and retronasal olfactory function.
Results. The IT-QOD was administered to 96 patients and 38 controls. The Cronbach’s
alpha exceeded 0.90, indicating satisfactory internal consistency. The test-retest reliability
was found to be high for both parosmia (rs = 0.944) and life quality (rs = 0.969). Pa-
tients with OD had significantly higher IT-QOD scores compared to healthy individuals
                                                                                                 Received: August 29, 2023
(p < 0.001), indicating strong internal validity. The external validity was also satisfactory,
                                                                                                 Accepted: October 16, 2023
as shown by the significant correlation with SNOT-22 (rs = -0.54) and the threshold, dis-
crimination, and identification score (rs = -0.63).
                                                                                                 Correspondence
Conclusions. The IT-QOD was demonstrated to be reliable and valid to assess the impact           Luigi Angelo Vaira
of OD on the quality of life of Italian-speaking patients.                                       E-mail: lavaira@uniss.it
KEY WORDS: olfactory dysfunction, parosmia, quality of life, anosmia, olfactory loss,
rhinology, maxillo-facial surgery, otorhinolaryngology                                             How to cite this article: Vaira LA, Tirelli G,
                                                                                                   Rizzo D, et al. Validity and reliability of the
                                                                                                   Questionnaire of Olfactory Disorders for Italian-
Introduction                                                                                       speaking patients with olfactory dysfunction.
                                                                                                   Acta Otorhinolaryngol Ital 2024;44:42-51.
Olfactory dysfunction (OD) is a common yet often overlooked condition that af-                     https://doi.org/10.14639/0392-100X-N2736
fects millions of people worldwide 1. This complex sensory impairment can mani-
                                                                                                 © Società Italiana di Otorinolaringoiatria
fest in various forms, such as anosmia (complete loss of smell), hyposmia (reduced               e Chirurgia Cervico-Facciale
ability to smell), or parosmia (distorted perception of smell). These olfactory dis-
turbances can arise from a multitude of causes, including head trauma, viral in-                                OPEN ACCESS
fections, neurodegenerative diseases, and aging 2. More recently, the COVID-19                   This is an open access article distributed in accordance with
                                                                                                 the CC-BY-NC-ND (Creative Commons Attribution-Non-
pandemic has brought OD into the spotlight, as it has emerged as a prevalent and                 Commercial-NoDerivatives 4.0 International) license. The
sometimes persistent symptom of SARS-CoV-2 infection 3. This increased atten-                    article can be used by giving appropriate credit and mentio-
                                                                                                 ning the license, but only for non-commercial purposes and
tion has led to a greater understanding and recognition of the challenges faced by               only in the original version. For further information: https://
individuals with OD, whether it is due to COVID-19 or other causes 4.                            creativecommons.org/licenses/by-nc-nd/4.0/deed.en




42
                                                                  Validation of the Italian version of the Questionnaire of Olfactory Disorders




In fact, the impact of OD on a patient’s quality of life is       languages 17,19. Two independent, bilingual translators with
frequently dramatic, as sense of smell plays a crucial role       Italian as their native language translated the questionnaire
in our daily lives 5,6. Smell influences our taste perception,    from German to Italian. One of the translators was an oto-
food preferences, and eating habits, as well as our ability to    laryngologist with expertise in olfactory disorders, while
detect potential environmental dangers. Additionally, olfac-      the other was a layperson, unaware of the questionnaire’s
tory cues are deeply intertwined with our emotional well-         purpose. Any disagreements that arose were resolved be-
being, social interactions, and the formation of memories 7.      tween the two translators, with the involvement of a third
Despite the significant impact of OD on patients’ quality         independent translator, if necessary, who was not involved
of life, there is currently only one validated specific instru-   in the previous translations. This initial Italian translation
ment available to assess it in individuals with olfactory dys-    was then back translated into German to ensure accuracy
function: the Questionnaire of Olfactory Disorders (QOD),         and to identify any potential misunderstandings. The back-
which exists in both a full length 8 and a short version 9.       translation was performed by two bilingual, German-native
Proposed in 2005 by Frasnelli and Hummel 8, QOD is a              translators who were unaware of the questionnaire’s con-
self-administered instrument designed specifically to as-         tent and purpose. The Italian version of the questionnaire,
sess the impact of OD on patients’ quality of life. It evalu-     resulting from the translation and back-translation process,
ates various aspects of patients’ experiences with olfactory      was subsequently evaluated by a panel of Italian-native ex-
disorders, addressing issues such as social and emotional         perts in olfactory disorders. The panel reached a consensus
well-being, food enjoyment, safety concerns, and daily            on each individual item, refining the translation as needed.
activities. In recent years, the QOD has been validated in        This prefinal version of the questionnaire was then admin-
English 10, Portuguese 11, Spanish 12, Korean 13, Chinese 14      istered to a sample of 10 respondents who were asked to
and French 15. The short version of the QOD was recently          complete the questionnaire and explain their understanding
validated in Italian 16. Cross-cultural validation of quality-    of each question-and-answer option.
of-life assessment tools is essential, as it ensures the ap-      The panel of experts analysed the responses to ensure that
plicability and accuracy of these instruments across diverse      there were no misunderstandings or misinterpretations of
populations. Cultural differences can influence the inter-        the questions and answers. A new consensus was reached
pretation and perception of various aspects of quality of         on each item, resulting in the definitive IT-QOD (Tab. I).
life, leading to potential discrepancies and misinterpreta-
tions when using non-validated instruments 17.                    Enrolment
To date, the adaptation and validation of the Italian ver-        The study included adult patients (> 18 years old) with
sion of the QOD have not been performed. Therefore, the           self-reported OD of any aetiology, who were followed up at
primary objective of this study is to adapt and validate          the Departments of Otorhinolaryngology, Rhinology, and
the Italian version of the QOD (IT-QOD), in order to pro-         Neurology of the participating centres. Enrolment was on
vide a reliable tool to assess Italian patients with olfactory    a voluntary basis, and patients were excluded if they were
dysfunction. This endeavour is of particular importance           not native Italian speakers, had severe systemic comorbidi-
considering that, in recent years, Italy has ranked second        ties that could predominantly affect their quality of life,
among countries worldwide in terms of the number of re-           had a prior psychiatric diagnosis before the onset of the
search articles produced on olfactory disorders 18.               olfactory disorder, or had neuropsychiatric comorbidities
                                                                  that could compromise their understanding of the question-
                                                                  naire. Using the same exclusion criteria, a control group
Materials and methods                                             was established, consisting of adult individuals who did not
Setting                                                           self-report the presence of an olfactory disorder.
This is a prospective, multicentre study conducted from Ju-
ly 2022 to April 2023 at the University Hospital of Trieste       Data collection
and at the University Hospital of Sassari in Italy.               For all individuals included in the study, general data were
                                                                  collected including age, gender, and comorbidities. In the
Questionnaire adaptation                                          case group, the subjective assessment of olfactory loss was
The adaptation of the IT-QOD originates from the original         conducted using the olfaction item of the COVID-19 Sever-
German version provided by Prof. Hummel from the Cen-             ity Index 20, which classifies olfactory function into three
tre for Olfactory Disorders in Dresden 8 (Supplementary I,        degrees: normal, reduced, and total loss of smell. The pres-
available online). The translation process followed estab-        ence of parosmia, phantosmia and gustatory disturbances
lished guidelines for adapting questionnaires to different        was assessed using a dichotomous assessment as either pre-



                                                                                                                                           43
L.A. Vaira et al.




sent or absent. Additionally, the duration and aetiology of                             Both cases and controls were administered the Sino-Nasal
the olfactory disorder were recorded.                                                   Outcome Test-22 (SNOT-22) and underwent psychophysi-



Table I. Italian translation from the original German version of the 29-items QOD.
 P1     Il cibo ha un sapore diverso da quello che dovrebbe avere a causa dei miei problemi con l’olfatto.                                  Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 P2       Avverto sempre un odore sgradevole nel naso, indipendentemente dalla presenza di una sostanza                                     Vero   
          odorosa nelle vicinanze.                                                                                            In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 P3       Gli odori che per altri sono gradevoli li avverto come sgradevoli.                                                                Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 P5       Il problema più grande per me non è tanto quello di percepire gli odori in modo più debole (o di non                              Vero   
          percepirli affatto), quanto il fatto che hanno un odore diverso da quello che dovrebbero avere.                     In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 1        A causa dei miei disturbi di olfatto vado meno spesso al ristorante con parenti o conoscenti.                                     Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 4        Ho sempre consapevolezza delle mie difficoltà nel sentire gli odori, dal risveglio all’andare a letto.                            Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 11       Le mie difficoltà con l’olfatto limitano anche la mia capacità di sentire i gusti.                                                Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 13       Mi chiedo se sarò mai in grado di venire a capo di questo problema.                                                               Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 14       Mantengo sempre una promessa, per quanto possa essere difficile fare ciò che ho detto.                                            Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 15       Mi sento più teso/a di prima a causa del cambiamento del mio olfatto.                                                             Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 17       Di tanto in tanto ho pensieri e idee che non vorrei gli altri scoprissero.                                                        Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 19       Quasi tutti i miei problemi dipendono dalle mie difficoltà con l’olfatto.                                                         Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 22       La difficoltà nel sentire gli odori mi disturba quando mangio.                                                                    Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
 23       Mi comporto sempre bene e in modo corretto.                                                                                       Vero   
                                                                                                                              In gran parte vero   
                                                                                                                         In gran parte non vero    
                                                                                                                                       Non vero    
                                                                                                                                            continues u


44
                                                                                       Validation of the Italian version of the Questionnaire of Olfactory Disorders




Table I. follows.
 26     Frequento conoscenti, parenti o vicini di casa meno spesso di prima a causa delle mie difficoltà nel                                           Vero   
        sentire gli odori.                                                                                                               In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 27      A causa delle mie difficoltà con l’olfatto mi è più difficile rilassarmi.                                                                     Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 28      Ho problemi di peso a causa delle mie difficoltà con l’olfatto.                                                                               Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 31      Tra tutti quelli che conosco ce ne sono alcuni che proprio non sopporto.                                                                      Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 32      Posso solo immaginare di imparare a convivere con il disturbo dell’olfatto.                                                                   Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 33      Le mie difficoltà con l’olfatto mi fanno sentire come escluso.                                                                                Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 34      Evito i gruppi di persone a causa delle mie difficoltà con l’olfatto.                                                                         Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 35      Le difficoltà con l’olfatto sono uno dei problemi della vita con i quali devo convivere.                                                      Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 36      Non sono mai arrivato tardi a un appuntamento o a lavoro.                                                                                     Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 37      A causa dei miei disturbi di olfatto mangio meno/più di prima.                                                                                Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 39      Ho paura di essere esposto a certi pericoli (p. es. gas domestico, cibo andato a male) a causa delle mie                                      Vero   
         difficoltà nel sentire gli odori.                                                                                               In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 42      Sorgono problemi nelle attività quotidiane a causa delle mie difficoltà con l’olfatto.                                                        Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 48      A volte parlo di cose delle quali non capisco nulla.                                                                                          Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 49      Le mie difficoltà con gli odori mi rendono nervoso.                                                                                           Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    
 50      A causa delle difficoltà con l’olfatto la mia relazione con il partner è danneggiata.                                                         Vero   
                                                                                                                                         In gran parte vero   
                                                                                                                                    In gran parte non vero    
                                                                                                                                                  Non vero    




                                                                                                                                                                45
L.A. Vaira et al.




cal evaluation of the olfactory function using the extended      rule of thumb of four patients per QOD item 25. Consider-
version of the Sniffin’ Sticks test (Medisense, Groningen,       ing a total of 29 items, the study planned to enrol at least
Netherlands), according to validated protocols and as pre-       116 patients.
viously described 21. The test allowed for the assessment        An explorative factor analysis was conducted to identify
of three domains of olfactory function: threshold (T), dis-      latent subscales, enhancing item loadings by means of
crimination (D), and identification (I), providing a TDI         oblique rotation. A minimum factor loading of 0.35 was
score that enables classification of olfactory function into     used as the criterion for associating an item with a specific
three categories: normosmia (TDI score ≥ 31), hyposmia           factor. Reliability (i.e. internal consistency) was evalu-
(TDI score 17-30.75), and anosmia (TDI score < 17) 22. All       ated within each subscale by calculating Cronbach’s al-
individuals included in the study were also subjected to the     pha coefficient. Items with reliabilities of 0.70 or greater
evaluation of retronasal olfactory function using 20 taste-      were considered as adequate, while a reliability criterion
less powders (Givaudan Schweiz AG, Dubendorf, Swit-              of 0.90 is recommended for analysing individual patient
zerland), as previously described 23. Approximately 0.05         items 25. Criterion-related validity (i.e. external validity)
grams of powder were placed on the dorsal surface of the         was evaluated for parosmia and quality of life subscales
patient’s tongue while blindfolded and with nostrils closed.     by correlating them with TDI score, retronasal olfactory
Once the powder was positioned, the patients were asked to       score, and SNOT-22 through the Spearman correlation
inhale deeply through their nose and attempt to identify the     coefficient. Discriminant validity was conducted by com-
perceived odour from four possible choices. The total score      paring subscales score in three groups of patients with
could range from 0 to 20, with 14 representing the cut-off       different olfactory impairment (i.e. controls, COVID-19
to define normal retronasal olfactory function.                  patients, and patients with sinonasal disfunction); dif-
The QOD is a validated tool related to the assessment of         ferences across groups were evaluated through Kruskal-
olfaction quality of life, originally comprised of 52 state-     Wallis test. Finally, test-retest reliability was analysed by
ments 8. The most recent original German version 24 in-          Spearman’s correlation coefficient.
cluded 29 statements that can be categorised into three sub-
scales: 19 negative and positive statements on quality of life
                                                                 Results
(QOD-QOL); 6 items on social desirability (QOD-DS); 4
items on parosmia (QOD-P). Negative statements describe          Ninety-six patients with OD and 38 healthy individuals
the extent to which patients suffer from olfactory impair-       completed the study. The characteristics of patients are
ment, while positive statements highlight how well patients      reported in Table II. The most prevalent comorbidities in-
cope with their olfactory impairment. ‘‘Socially desired’’       cluded allergic rhinitis and asthma. The causes of OD main-
statements – similar to the ‘‘lie scale’’ of the Eysenck Per-    ly consisted of post-viral (34.3%) and sinonasal (27.6%)
sonality Inventory (EPI) – reflect whether patients give         disorders. The explorative factor analysis identified three
answers that they believe they are expected to give. This        subscales (Tab. III), in agreement with the original Ger-
domain was crafted to gauge the authenticity of an individ-      man version of QOD; only item P1 loaded on two differ-
ual’s or to discern if they were trying to convey a specific     ent factors, i.e. life quality and parosmia. Internal consist-
impression by providing socially agreeable responses. Pa-        ency was evaluated for each subscale, reporting adequate
tients could agree (2 points), partly agree (1 point) or disa-   consistency (i.e. Cronbach’s alpha coefficient > 0.90) for
gree (0 point) with each statement 8. The aggregate scores       life quality statements (Tab. IV). Internal consistency was
for QOD-QOL and QOD-P ranged between 0-57 and 0-12,              quite poor for sincerity statements. Discriminant validity
respectively. A higher score represents greater impairment.      of the IT-QOD was evaluated by comparing median sub-
The total score for QOD-DS ranged between 0-18. A high-          scale values according to aetiology of OD (Fig. 1). As ex-
er score means a tendency toward giving a socially desired       pected, the median score for parosmia and life quality was
answer, implying that the results might lack credibility. To-    lower in controls than in patients with olfactory impairment
tal and sub-scale scores were finally converted in a 0-100%      (p < 0.001), considered overall and according to the aeti-
scale according to QOD manual.                                   ology of olfactory dysfunction; these results confirm the
The entire evaluation procedure was conducted twice, with        capability of the IT-QOD to discriminate between groups
a 7-day interval between the two assessments, to ascertain       with different olfactory impairment.
the test-retest reliability of the IT-QOD.                       Satisfactory criterion validity emerged for life quality state-
                                                                 ment, resulting in absolute value of the Spearman’s cor-
Statistical analysis                                             relation coefficient > 0.50 with TDI score and SNOT-22
The required sample size was determined according to the         (Tab. V). Mild correlation also emerged for parosmia score,



46
                                                                                 Validation of the Italian version of the Questionnaire of Olfactory Disorders




with absolute Spearman’s correlation coefficient between
0.35 and 0.48. Finally, both parosmia and life quality sub-
scales were successfully tested for reproducibility, with a
Spearman’s correlation coefficient > 0.90 in the test-retest
procedure (Tab. VI).

Discussion
Questionnaires currently represent the gold standard to
assess the effects of olfactory disorders on quality of life.
Among the various available tools, the QOD is the most
widely utilised, due to its comprehensive nature and reli-
able methodology. The QOD was designed to provide a ro-
bust measure of the impact of olfactory disorders on several
aspects of life. It allows clinicians to better understand the
depth and breadth of their patients’ experiences and provides
a standardised mean of quantifying and comparing the ef-
fects of different disorders and treatments. However, despite


Table II. Clinical and sociodemographic characteristics of enrolled patients.
 Characteristics                                 n                 (%)
 Gender
   Female                                         68             (50.7)
   Male                                           66             (49.3)
 Age (years)
   Median (Q1-Q3)                             52 (29-44)
 Tobacco smoking
   No                                            109             (81.3)         Figure 1. Subgroup analysis of the differences in parosmia and quality of
                                                                                life scores.
   Yes                                            25             (18.7)
 Comorbidities
   Allergic rhinitis                              31             (23.1)         its widespread international use, there is currently no Italian
   Asthma                                         31             (23.1)         version of the QOD. This gap presents a significant hurdle
   Cardiovascular disease                         19             (14.2)         for Italian-speaking researchers and clinicians who aim to
   Arthrosis                                      14             (10.5)         assess quality of life in patients with olfactory disorders.
   Depression                                     11              (8.2)         The process of cross-cultural adaptation of a questionnaire
   Active or former cancer                         6              (4.5)         into another language is a complex endeavour, encompass-
   Psoriasis                                      4               (3.0)         ing all the steps undertaken in this study. These steps aim
   Rheumatological diseases                       4               (3.0)         to produce a tool that measures outcomes consistently with
   Renal failure                                  1               (0.8)         the original instrument, ensuring data continuity and compa-
   Liver failure                                  0               (0.0)         rability across different linguistic and cultural backgrounds.
   Respiratory failure                            0               (0.0)         Consistent with the original version, the questionnaire
 Aetiology of the olfactory disorder                                            items can be grouped into three subscales evaluating: pa-
   Post-viral                                     46             (34.3)         rosmia, quality of life, and sincerity. The items aligned with
   Sinonasal                                      37             (27.6)         the same factors as in the original questionnaire, showcas-
   Post-traumatic                                  8              (6.0)         ing the reliability of the questionnaire’s construct. Only one
   Neurological                                    3              (2.2)         parosmia item spanned two subscales (quality of life and
   Idiopathic                                      2              (1.5)         parosmia), while an item originally included in the sincer-
   Control                                        38             (28.4)         ity statements instead fell into the quality of life subscale.



                                                                                                                                                          47
L.A. Vaira et al.




Table III. Item factor loading.
 #                                                          Item                                                   Factor 1      Factor 2   Factor 3
                                                                                                                  Life quality   Parosmia   Sincerity
 P1         Food tastes different from what used to.                                                                 0.58          0.36      -0.31
 P2         Often I perceive a bad smell, regardless whether a potential odour source is present.                    0.25          0.74      -0.02
 P3         Other people find odours pleasant which are unpleasant to me.                                            0.26          0.86      0.18
 P5         My biggest problem is not that odours are less intense (or absent), but that things smell different      0.17          0.87      0.00
            from what they used to.
 1          Because of the changes in my sense of smell, I go to restaurants less often than I used to.               0.72        -0.03      -0.15
 4          I am always aware of the changes in my sense of smell.                                                    0.73         0.03      -0.42
 11         Because of the changes in my sense of smell, I don’t enjoy drinks or food as much as I used to.           0.66         0.29      -0.26
 13         I am worried that I will never get used to the changes in my sense of smell.                              0.64         0.37      -0.36
 S14        I always keep my promises, no matter what the cost.                                                       0.02         0.35      -0.25
 15         Because of the changes in my sense of smell, I feel more anxious than I used to feel.                     0.85         0.15      -0.11
 S17        Sometimes I have thoughts and ideas I would not want other people to know of.                            -0.03         0.03       0.80
 19         The changes in my sense of smell cause most of my problems.                                               0.77         0.18       0.04
 22         The changes in my sense of smell annoy me when I am eating.                                               0.70         0.17      -0.25
 S23        I always behave well and properly.                                                                       -0.05         0.12      -0.36
 26         Because of the changes in my sense of smell I visit friends, relatives, or neighbours less often.        0.76          0.08       0.16
 27         Because of the changes in my sense of smell, I try harder to relax.                                      0.82          0.19       0.05
 28         Because of the changes in my sense of smell I have weight problems.                                      0.73          0.14       0.09
 S31        Among all people I know, there is someone I can’t stand.                                                 0.03          0.10       0.51
 32         I am wondering if I will ever be able to live with this problem.                                         0.61          0.16      -0.27
 33         The changes in my sense of smell make me feel isolated.                                                  0.74          0.03       0.07
 34         Because of the changes in my sense of smell I avoid groups of people.                                    0.68          0.14       0.20
 35         This problem is just one of the many problems in life one has to live with.                              0.48          0.19      -0.25
 S36        I have never been late for an appointment or work.                                                       0.14         -0.02      -0.53
 37         Because of the changes in my sense of smell I eat less than I used to or more than I used to.            0.84         0.12        0.02
 39         Because of the difficulties with smelling, I am scared of getting exposed to certain dangers (e.g.,      0.75         0.16       Ì0.25
            gas, rotten food).
 42         Because of the changes in my sense of smell I have problems with taking part in activities of daily      0.85          0.11      -0.26
            life.
 S48        Sometimes I talk about things I don’t know.                                                              -0.05        -0.06       0.58
 49         The changes in my sense of smell make me feel angry.                                                     0.87         0.14        0.05
 50         Because of the changes in my sense of smell, my relationship with my wife / husband / partner is         0.55         0.02        0.15
            affected.
Loadings ≥ 0.35 are in bold.



The enrolment of patients in the present study respected the                        to that reported for the French version (Cronbach’s alpha
same inclusion and exclusion criteria as the original study                         0.827) 15, English version (Cronbach’s alpha 0.90) 10, and
in which the German version of the questionnaire was vali-                          the original German version (Cronbach’s alpha 0.93) 8.
dated. The original population consisted of 84 males and                            Like the French version, the consistency of the sincerity
121 females, with a mean age of 53.6 years, which is quite                          statements was found to be weaker. This suggests that,
similar to ours in terms of age (median age, 52), while we                          while these sections translated well and provided consist-
had a less marked proportion of women (68 women and                                 ent results across different languages and cultures, the
66 men in our study). It is not possible to compare the two                         sincerity statements might require further adaptation to fit
populations by aetiology of OD because this was not re-                             cultural nuances better or may inherently have more vari-
ported by Frasnelli and Hummel 8.                                                   ability across different populations.
The Italian version demonstrated high internal consistency                          The discriminant validity was high, and the Italian version
for the quality of life and parosmia subscales, comparable                          of the QOD detected significantly worse quality of life and



48
                                                                                      Validation of the Italian version of the Questionnaire of Olfactory Disorders




Table IV. Subscale internal consistency of the IT-QOD. Item-to-total correlation and Cronbach’s alpha for questionnaire items.
 #     Item                                                                                                           Item-to-total         Cronbach’s alpha if
                                                                                                                        correlation           item is deleted
 Parosmia statements
 P1      Food tastes different from what used to.                                                                           0.317                   0.849
 P2      Often I perceive a bad smell, regardless whether a potential odour source is present.                              0.576                   0.671
 P3      Other people find odours pleasant which are unpleasant to me.                                                      0.679                   0.614
 P5      My biggest problem is not that odours are less intense (or absent), but that things smell different from           0.696                   0.585
         what they used to.
 Life quality statements
 1       Because of the changes in my sense of smell, I go to restaurants less often than I used to.                        0.680                   0.952
 4       I am always aware of the changes in my sense of smell.                                                             0.747                   0.951
 11      Because of the changes in my sense of smell, I don’t enjoy drinks or food as much as I used to.                    0.700                   0.952
 13      I am worried that I will never get used to the changes in my sense of smell.                                       0.724                   0.951
 15      Because of the changes in my sense of smell, I feel more anxious than I used to feel.                              0.846                   0.949
 19      The changes in my sense of smell cause most of my problems.                                                        0.742                   0.951
 22      The changes in my sense of smell annoy me when I am eating.                                                        0.722                   0.951
 26      Because of the changes in my sense of smell I visit friends, relatives, or neighbours less often.                  0.682                   0.952
 27      Because of the changes in my sense of smell, I try harder to relax.                                                0.792                   0.950
 28      Because of the changes in my sense of smell I have weight problems.                                                0.676                   0.952
 32      I am wondering if I will ever be able to live with this problem.                                                   0.634                   0.952
 33      The changes in my sense of smell make me feel isolated.                                                            0.680                   0.952
 34      Because of the changes in my sense of smell I avoid groups of people.                                              0.623                   0.953
 35      This problem is just one of the many problems in life one has to live with.                                        0.508                   0.955
 37      Because of the changes in my sense of smell I eat less than I used to or more than I used to.                      0.800                   0.950
 39      Because of the difficulties with smelling, I am scared of getting exposed to certain dangers (e.g., gas,           0.764                   0.951
         rotten food).
 42      Because of the changes in my sense of smell I have problems with taking part in activities of daily life.          0.853                   0.949
 49      The changes in my sense of smell make me feel angry.                                                               0.841                   0.949
 50      Because of the changes in my sense of smell, my relationship with my wife / husband / partner is                   0.477                   0.954
         affected.
 Sincerity statements
 S14 I always keep my promises, as hard as it is.                                                                           0.051                   0.182
 S17 Sometimes I have thoughts and ideas I would not want other people to know of.                                          0.197                   0.031
 S23 I always behave well and properly.                                                                                      0.04                   0.189
 S31 Among all people I know, there is someone I can’t stand.                                                               0.230                   0.008
 S36 I have never been late to an appointment or work.                                                                      -0.166                  0.374
 S48 Sometimes I talk about things I don’t know.                                                                             0.148                  0.093




Table V. Criterion validity of the IT-QOD. Spearman correlation coefficient          Table VI. Reliability of the IT-QOD. Spearman correlation coefficient between
with TDI, retronasal olfactory score, and SNOT-22 for parosmia and life quality      first and second test administration for subscales.
statement outcome.                                                                     Score                                   Spearman correlation coefficient
 Score                                Spearman correlation coefficient                Parosmia                                              0.915
                                    Parosmia                Life quality              Life quality                                          0.969
 TDI                                   -0.48                    -0.63                 Sincerity                                             0.791
 Retronasal olfactory score            -0.35                    -0.47
 SNOT-22                               0.44                     0.54




                                                                                                                                                               49
L.A. Vaira et al.




parosmia scores in patients with OD compared to controls.        Conclusions
Moreover, different score patterns were detected based on
                                                                 In conclusion, the Italian translation of the original German
the aetiology of the OD. Patients with COVID-19 related
                                                                 version of the olfactory disorder’s questionnaire is a valid,
OD had significantly worse parosmia scores compared to
                                                                 reliable, and context-based scale. It will facilitate cross-
patients with OD from sinonasal disease. In patients with
                                                                 cultural comparisons and allow for more comprehensive
post-viral olfactory disorders, the higher prevalence of pa-
                                                                 understanding of olfactory disorders and their impact on
rosmia is evident. Specifically, when comparing patients
                                                                 adult individuals. Moreover, in clinical practice, the ques-
with qualitative disorders to those with isolated quanti-
                                                                 tionnaire can serve as a valuable tool for Italian healthcare
tative disorders, the analysis shows significantly worse
                                                                 professionals in assessing and monitoring the severity and
parosmia scores and a non-significant decline in quality
                                                                 quality of life impact of olfactory disorders in their patients.
of life in the former group compared to the latter. The
                                                                 This can aid in treatment planning, evaluating therapeutic
impact of qualitative disorders on quality of life, which is
                                                                 interventions, and tracking patients’ progress over time.
even more pronounced than that of quantitative disorders,
has been extensively documented and appears to be sup-           Conflict of interest statement
ported by this study, although statistical significance was      The authors declare no conflict of interest.
not reached. Criterion validity was also satisfactory with
moderate and significant correlations between the QOD            Funding
scores and all analysed parameters (i.e. TDI, retronasal ol-     This research did not receive any specific grant from fund-
factory score, and SNOT-22). The correlations were in all        ing agencies in the public, commercial, or not-for-profit
cases stronger with the quality of life subscale than with       sectors.
the parosmia score. This is not surprising because the se-
verity of parosmia is not directly proportional to olfactory     Author contributions
loss, and patients with qualitative disorders, even severe       LAV and PBR have full access to all the data in the study
ones, can present normal psychophysical olfactory scores.        and take responsibility for the integrity of the data and the
The strength of the correlations is similar to that reported     accuracy of the data analysis. LAV, GT, GDR, PBR: con-
for the French version, for which the SNOT-22 was used           ceptualization and methodology. DR, FU, FA, DR, NR,
for criterion validation (rs = 0.498; p = 0.001). Unlike in      LC, PS: acquisition, analysis and interpretation of the data.
this study, where the correlation with TDI was found to          PBR, LAV: statistical analysis. JRL, MM: critical revision
be moderate and significant, the correlation between psy-        of the literature. FB, PS: provision of resources. LAV, PBR:
chophysical test results and QOD scores was found to be          original draft preparation. JRL, MM, GT, GDR, DR, FU,
weak and significant in the German version (rs = -0.015;         FA, FT, DR, NR, LC, PS: critical revision of the manuscript
p = 0.034) and not significant in the English version. Fi-       for important intellectual content. GT, GDR: supervision.
nally, in line with previous findings, the reproducibility       All the authors read and approved the final version of the
of QOD was demonstrated to be reliable, as evidenced             manuscript.
by strong and significant correlations observed between
the two evaluations performed for each patient. This study       Ethical consideration
has the strength of proposing and validating, through a          This study was approved by the University of Trieste Eth-
rigorous and comprehensive process, the IT-QOD. This is          ics Committee (approval N. CEUR-2020-Os-156) and
of substantial value as it provides researchers with a reli-     University of Cagliari Ethics Committee (approval N.
able tool to evaluate the quality of life in Italian-speaking    PG/2021/7118). The research was conducted ethically,
patients with olfactory disorders.                               with all study procedures being performed in accordance
As for the limitations of the study, it should be acknowl-       with the requirements of the World Medical Association’s
edged that the majority of patients in the study had post-       Declaration of Helsinki.
viral OD or OD related to chronic rhinosinusitis. This may       Written informed consent was obtained from each partici-
restrict the generalisability of the findings and the applica-   pant/patient for study participation and data publication.
bility of the QOD instrument in assessing the quality of life
in patients with OD of other causes. Finally, the study did      References
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