to the editor: In her article, “Omega-3 Fatty Acids,”¹ in American Family Physician, Dr. Covington provides a thorough review of omega-3 fatty acids. A challenge for readers, however, is deciding how to change their practice based on a review. Reviews describe the included studies but often not their quality. In addition, the selection of references in a review may create a bias. These issues are addressed by performing a systematic review, which attempts to rigorously examine, evaluate, and synthesize all relevant studies on a given topic.

As one example of a different conclusion reached by a review and a systematic review, Dr. Covington described studies that reported improvement in patients with rheumatoid arthritis who take omega-3 fatty acids. However, a recent systematic review² found no significant improvement in pain, swollen joint count, or patient global assessment in those taking omega-3 fatty acids.

This systematic review² was one of a series on omega-3 fatty acids developed by the Agency for Healthcare Research and Quality’s Evidence-based Practice Centers Program in partnership with the National Institutes of Health Office of Dietary Supplements. Reports also have been released on omega-3 fatty acids and other topics such as cardiovascular disease, cancer, type 2 diabetes, asthma, mental health, organ transplantation, and cognitive function. These can be accessed online athttp://www.ahrq.gov/clinic/epcix.htm. Reports on maternal and child health and eye health care are in progress. Compared with narrative reviews, systematic reviews such as these can provide a more accurate assessment of the evidence for an intervention’s safety and efficacy.

editor’s note: This letter was sent to the author of “Omega-3 Fatty Acids,” who declined to reply.