There's little denying that the technological, research, and medicinal aspects of patient care are improving at breakneck speed. But sometimes, even the best medical care in the world just isn't enough to help someone. Occasionally this is because of the nature of a disease itself (i.e., many diseases still aren't well understood or are resistant to current medication), but in other case cases it's because of a patient being improperly diagnosed or receiving a delayed diagnosis.

Source: Rhoda Baer, National Cancer Institute.

The onus of a misdiagnosis is often placed on the physician, and with good reason -- they're the doctors, and we expect them to be all-knowing. However, plenty of misdiagnoses or delayed diagnoses can also be attributed to patient negligence in failing to take action in a timely manner when symptoms present themselves. Disease misdiagnosis is a two-way street that has plenty of room for improvement, but until recently had also been largely misunderstood -- that is, until a study in 2009 shed light on the most commonly misdiagnosed diseases.

Before this study, there had been no large database chronicling misdiagnoses, thus leaving no way for patients or physicians to know what diseases they should pay extra special care in diagnosing. And that's kind of a big deal, with as many as 98,000 people dying each year from preventable diseases because of medical errors.

However, a team of five physicians in Fort Lauderdale, Fla., sought to rectify this problem by compiling a meta-analysis (a fancy word for combining and comparing statistical results from multiple studies) of autopsy and malpractice data. The final research for this study included data from 31 separate reports.

The benefit of this data is twofold: it exposes problem areas in diagnosing certain diseases, which should help improve attention to detail from both physicians and patients exhibiting those symptoms, and it highlights the potential for more accurate diagnostic equipment. As investors, it also gives us definable opportunities to take advantage of instances where certain medicines or diagnostics may greatly increase in usage to improve patients' quality of life.

Here are the study's results for the five most misdiagnosed diseases based on autopsy and malpractice data, combined.

No. 5: Cardiovascular disease
According to the Centers for Disease Control and Prevention, heart disease was the leading cause of death in the U.S. in 2011 (responsible nearly 600,000 deaths), so it's not surprising to see it among the most commonly misdiagnosed diseases. A big concern here lies with the patient and in their ability to relay symptoms to their doctor. A heart attack, for example, may present relatively few symptoms, such as general nausea and a feeling of being full in a patient's chest. A doctor, in turn, needs to be able to recognize subtle symptoms as a possible sign of heart disease and not hesitate to order follow-up tests.

One simple way of reducing your chances of developing a cardiovascular disease is by getting more preventative screenings. Based on a CDC report, nearly one-third of U.S. adults have high cholesterol and high blood pressure, making it all the more important that people take this preventative step. This sheds light on next-generation cholesterol-lowering medications like oft-highlighted Liptruzet which was approved by the Food and Drug Administration in May and could see a bump in sales if more people took this preventative step. Liptruzet, which combines the now generic LDL-fighting power of Pfizer's Lipitor, with the cholesterol absorption inhibiting prowess of Merck's Zetia, lowered LDL-cholesterol (the bad type) by 53% to 61% in patients -- a much bigger reduction than each drug delivered individually.

No. 4: Pulmonary emboli
A pulmonary embolism is a blockage of an artery in the lungs by any number of things, including fat, blood clots, and tumor cells. Perhaps the biggest factor to be concerned with here relates to your chance of developing a blood clot following surgery. Last month we discovered that venous thromboembolisms (deep-vein thrombosis and pulmonary embolisms) are the leading cause of preventable patient death in hospitals with the U.S. Department of Health and Human Services estimating that 1.1% of all surgical patients will develop a blood clot. The key here would be for physicians to properly screen for and diagnose patients that have a higher risk of developing a blood clot in a post-surgical setting.

Diagnostic equipment could be called on to come to the rescue here, but I see this as a huge opportunity for Pfizer and Bristol-Myers Squibb's recently approved blood-thinner Eliquis. At the moment, Eliquis is only approved to treat blood clots in patients with atrial fibrillation, but could see sales surge if it gets the expanded indication to treat post-surgical patients. Even if it's just a short-term treatment (the threat for post-surgical blood clots usually abates after a few weeks), the boost in sales could be enormous, and the chance of developing a blood clot for surgical patients could be dramatically reduced.

No. 3: Myocardial infarctions
Now we're literally talking about a heart attack! A myocardial infarction is nothing more than a blood flow blockage to your heart which causes muscle tissue damage and/or death in and around the heart. As I discussed above, some of the symptoms of a heart attack can be very subtle, so it's important for patients to discuss all their symptoms, regardless of how minor, with their doctor, and for that physician to order the proper diagnostic tests.

In diagnosing a heart attack the biggest obstacle is time, because once a diagnosis is made it can sometimes be too late. Preventative measures, such as ensuring your LDL-cholesterol is low; that your blood pressure is within normal ranges; and, should you have diabetes, that you are properly maintaining your condition through medication and proper diet, are all important factors to reducing your chance of a heart attack. A family history of heart attack also genetically puts you at a higher risk of a myocardial infarction, thus increasing the urgency that you take preventative steps early in life to avoid a disease like this, or worse, a misdiagnosis, later in life.

No. 2: Neoplasms
You may not recognize the scientific name, but a neoplasm is an abnormal growth of tissue most commonly referred to as cancer. Keep in mind that neoplasms can be benign as well, so with increasingly better medication and early stage detection in some cancer types, it's no longer the death sentence it once was. However, properly diagnosing cancer can often be very difficult if the needed tests aren't ordered or a patient's subtle symptoms aren't taken into account.

According to the study's findings, a disheartening 12% of all cancers -- one in eight -- are misdiagnosed from the start! Based on malpractice data from the meta-analysis, the deadly form of skin cancer known as melanoma tops the list as the most commonly misdiagnosed cancer type.

There could, however, be good news on the way for patients who have, or think they have, a certain type of melanoma. In May the FDA approved two new single-agent melanoma medications developed by GlaxoSmithKline , Tefinlar and Mekinist, as well as a companion diagnostic test known as THxID BRAF. The diagnostic test identifies the BRAF mutation in melanoma (the most common mutation in melanoma) while each unique new medication delayed tumor growth in patients for a longer period than those taking just the placebo.

No. 1: Infections
But the No. 1 misdiagnosis by physicians is infection. An anonymous survey of physicians with regard to children's health published in the journal Pediatrics noted that slightly more than half improperly diagnosed a viral infection as a bacterial infection during the course of the year.

The key to a properly diagnosed infection is in ensuring that your doctor performs the required follow-up tests. A patient needs to be forthcoming with all of his or her symptoms and physicians need to be diligent and thorough with their protocol for infection diagnosis.

Where do we go from here?
In addition to increasing the awareness for both patients and physicians around these five commonly misdiagnosed diseases, I believe it opens up the door for advancements in diagnostic and molecular technologies.

Source: Army Medicine, Flickr.

In cancer diagnostics, for instance, we're just touching the tip of the iceberg with regard to personalizing the therapy for better care and quicker diagnoses. Life Technologies introduced its Benchtop Ion Proton Sequencer early last year which can map the human genome in less than 24 hours for a cost of just $1,000. Quicker and more accurate results could make mapping the genome of cancerous tumors quicker than ever which would in turn help in diagnosing mutations and properly prescribing the best treatments for a particular cancer type.

Another prime example here would be Navidea Biopharmaceuticals' Lymphoseek which is an injectable agent used in external lymph-node imaging and intra-operative lymphatic mapping. In English this means it will dramatically improve the staging and treatment options for patients with breast cancer. Being that breast cancer was also listed as a commonly misdiagnosed cancer, this is a big step in the right direction for patient care.

Editor's Note: The final sentence in the "No. 1 Infection" section has been edited, and a typo in the same section has been corrected. The Fool regrets the error.


The article The 5 Most Misdiagnosed Diseases originally appeared on



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