...patients are increasingly gaining access to medical information and then looking to their physicians for its interpretation. Gone are the days when what the physician says goes unchallenged by a naive patient. The public is inundated with medical advice and contrary views from the newspaper, radio, television, popular lay journals, and the Internet, and physicians are faced with the task of damage control.
Physicians also encounter constantly changing recommendations for clinical practice and an information jungle. With 6 million medical articles published each year, the amount of information available is overwhelming. If clinicians, trying to keep up with all of the literature, were to read two articles per day, in just 1 year, they would fall 82 centuries behind in their reading!
Despite this gargantuan volume of medical literature, less than 15 percent of all articles published on a particular topic are useful. Most articles are not peer-reviewed, are sponsored by those with commercial interests, or arrive free in the mail. Even articles published in the most prestigious journals are far from perfect. Analyses of clinical trials published in a wide variety of journals have described large deficiencies in the design, analysis, and reporting; although improving with time, the average quality score of clinical trials during the past two decades is less than 50 percent. As a result, many diagnostic tests and therapies are not rigorously evaluated before becoming established as a routine part of practice, which leads to the widespread use of tests with uncertain efficacy and treatments that are either ineffective or that may do more harm than good. Readers must thus take personal responsibility for judging the validity and clinical importance of the medical literature.
The challenge to physicians is to provide up-to-date medical care incorporating valid new information. Our ultimate goal as clinicians should be to help patients live long, functional, satisfying, pain- and symptom-free lives. To do so requires us to balance compassion with competence. One of the essential skills needed to maintain competence, to provide patients with the best possible care, and to do more good than harm is the ability to critically appraise the literature. We must be able to find potentially relevant information, filter out the best from the much larger volume of less credible information, and then judge whether to believe the information that remains.
The two major types of studies reported in the medical literature are (1) those that report original research (analytic, primary studies), and (2) those that summarize or draw conclusions from original research (integrative, secondary studies). Primary studies can be either experimental (an intervention is made) or observational (no intervention is made). The purpose of this article is to provide an overview of a systematic, efficient, and effective approach to the critical review of original research. This information is pertinent to physicians no matter what their setting, be it an academic medical center or a rural solo practice. Because of space limitations, this article cannot address everything in exhaustive detail, and the reader is encouraged to refer to the suggested readings at the end for further assistance.
With an article in hand, the process involves three steps: (1) screen for initial validity and relevance, (2) determine the intent of the article, and (3) evaluate the validity of the article based on its intent. This paper focuses on the type of study most germane to clinical practice: a therapeutic intervention. To make the most of this exercise, it would be helpful for the reader to obtain a copy of the article mentioned in case 2, and to follow the steps outlined below. The users' guides and other resources listed at the end of this paper are helpful in learning how to appraise other types of articles.