According to a new study, Wikipedia's medical articles contain numerous errors, or at least don't line up with up-to-date, peer-reviewed journals. In fact, nine out of 10 of the diseases identified as most costly for the healthcare system by the Agency for Healthcare Reform and Quality (AHRQ) had a statistically significant discrepancy between the two.

In the study, published in The Journal of the American Osteopathic Association, two medical students independently went through a printed version of each of the articles and identified all factual assertions. They then checked those facts on (in this order) UpToDate, PubMed, and Google Scholar.

The 10 conditions that were identified in the study were lung cancer, diabetes, osteoarthritis, coronary artery disease, COPD, hyperlipidemia, concussion, hypertension, major depressive disorder, and back pain. Of those only the concussion article was free of a significant number of discrepancies.

These findings may not come as a surprise to many people. But the researchers say they undertook the study because medical students, if not practicing doctors, do use Wikipedia.

"Wikipedia's prominence has been made possible by its fundamental design as a wiki, or collaborative database, allowing all users the ability to add, delete, and edit information at will. However, it is this very feature that has raised concern in the medical community regarding the reliability of the information it contains," the authors write. "Despite these concerns, Wikipedia has become a popular source of health care information, with 47 percent to 70 percent of physicians and medical students admitting to using it as a reference. In actuality, these figures may be higher because some researchers suspect its use is underreported. Although the effect of Wikipedia's information on medical decision making is unclear, it almost certainly has an influence."

Recent studies have shown that in addition to some doctors using Wikipedia for medical research, patients certainly do as well.

In January of this year, an IMS report on pharma and social media looked at patient engagement with Wikipedia, which they found was a major source for disease information. They found that the top 100 Wikipedia pages related to healthcare were accessed on average 1.9 million times over the last year, with tuberculosis receiving the most views at 4.2 million, and acne vulgaris getting the least views with 1.3 million. In addition to patients, the report found that 50 percent of physicians use Wikipedia, particularly for up-to-date information on particular conditions.

IMS tracked Wikipedia page views against related medication sales and concluded that patients were using Wikipedia at various points in their diagnosis and treatment, with young people proving more likely to research a disease before deciding on a treatment, and older people more likely to look for information once their treatment has already begun.

Finally, in a survey conducted last month by Markovsky Health, Wikipedia was the second-most viewed online source of health information by patients, surpassed only by WebMD.

Typically when those who know better find mistakes in Wikipedia articles, they fix them. No word on whether the researchers corrected the articles they studied.