Prevalence and outcomes of anemia in rheumatoid arthritis: a systematic review of the literature.

Anemia is a common comorbidity in individuals with rheumatoid arthritis (RA). In fact, anemia of the type characterized by low serum iron concentrations in conjunction with adequate iron stores is frequently associated with RA and has served as a model for anemia of chronic disease. A systematic search of the scientific literature published since January 1966 identified 19 articles that reported findings on either the prevalence of anemia in patients with RA or outcomes for patients with anemia and RA. Ten articles addressed the prevalence of anemia in patients with RA. Estimates of the prevalence of mild anemia ranged between 33% and 60%; however, the 2 studies that examined demographics in patients with RA did not identify subpopulations at particular risk for anemia. Twelve articles assessed the impact of the resolution of anemia on symptoms and quality of life (QOL) in patients with RA. For many of the parameters assessed-including swollen, painful, and tender joints, pain, muscle strength, and energy levels-a positive correlation was observed between improvement of symptoms and the resolution of anemia. In addition, 2 studies reported a significant improvement in QOL scores in patients with RA who experienced a response to treatment for anemia. These results suggest that (1) patients with RA who have anemia are likely to have more severe joint disease and (2) if the anemia is successfully treated, the joint disease will likely respond to treatment as well. Whether improvements in QOL and/or joint symptoms occur with improvement of anemia, independent of other signs of an overall response to RA therapy, remains to be determined.