CQAIMH - center for quality assessment and improvement in mental health

Depression Screening

Depressive episodes are characteristic of both major depressive (unipolar) disorder and bipolar disorder. Studies show that bipolar depression is frequently misdiagnosed as unipolar depression:

  • 30% of patients in a family practice setting who were determined to be depressed, anxious or both were identified as having bipolar disorder; mainly bipolar II disorder. (1)
  • 56% of patients diagnosed with unipolar disorder in a primary care psychiatric sample were later found to have bipolar spectrum disorders. (2)
  • In a low income primary care clinic, approximately 25% of the patients diagnosed with major depression had lifetime bipolar depression. (3)

Patient Health Questionnaire-2 (PHQ-2): The PHQ-2 screen is a 2-item self report that inquires about the frequency of depressed mood and anhedonia over the last two weeks.

  • The purpose of the PHQ-2 is to screen for depression in a “first step” approach.
  • The PHQ-2 includes the first 2 items of the PHQ-9.
  • Patients who screen positive with the PHQ-2 should be further evaluated with the PHQ-9, other diagnostic instrument(s) or direct interview.

Patient Health Questionnaire (PHQ-9): The PHQ-9 is an instrument that screens for and diagnoses depression based on DSM-IV criteria.

  • The specific items included in the scale include the 9 diagnostic criteria for making a DSM-IV depression diagnosis.
  • The brevity and self-report of PHQ-9 lends itself well to clinical practice settings.
  • The PHQ-9 has the potential of being a dual-purpose instrument that can establish depressive disorder and assess depressive symptom severity. The PHQ-9 can also be used in serial fashion to monitor symptoms over time.
  • The PHQ-9 also has questions that screen for the presence and severity of suicidal ideation and functional impairment based on depressive symptomatology.


  1. Manning JS, Haykal RF, Connor PD, Akiskal HS; On the nature of depressive and anxious states in a family practice residency setting: the high prevalence of bipolar II and related disorders in a cohort followed longitudinally; Compr. Psychiatry 1997; 38: 102-108
  2. Ghaemi SN, Boiman EE, Goodwin FK, Diagnosing bipolar disorder and the effect of antidepressants: a naturalistic study, J. Clin Psychiatry 2000; 61: 804-808
  3. Olfson M, Das AK, Gameroff MJ, Pilowsky D, Feder A, Gross R, Lantigua R, Shea S, Weissman MM, Bipolar depression in a low-income primary care clinic; Am J Psychiatry, 2005 Nov: 162 (11) 2146-51
