"Severe chronic anemia (hemoglobin <10 gm/dL) is rare (3.4%), but mild chronic anemia is common, occurring in 35.3% compared with rates of <10% in the general population," Dr Fred Wolfe (National Data Bank for Rheumatic Diseases, Wichita, KS) said.

Severe chronic anemia is rare, but mild chronic anemia is common, occurring in 35.3%, compared with rates of <10% in the general population.

In a study supported by Ortho Biotech Products, LP, Wolfe and coauthor Dr Kaleb Michaud (National Data Bank for Rheumatic Diseases) used data from the National Data Bank for Rheumatic Diseases to determine the prevalence, severity, and consequences of anemia in RA patients. This has some major clinical and economic implications. Anemia contributes to fatigue and other problems in RA patients, and makers of potent (and expensive) hematologic support agents such as recombinant epoetin alfa (Ortho's Procrit or Eprex, Amgen's Epogen) have been working steadily in recent years to gain acceptance for use of these agents at milder stages of anemia. Current treatment guidelines in many clinical areas, such as cancer, typically recommend epoetin support only when hemoglobin (Hb) levels drop below 10 mg/dL.

Wolfe analyzed more than 30¿000 Hb determinations from 2120 consecutive RA patients and 3843 patients with noninflammatory rheumatic disorders (NIRD). "Anemia occurred in 31.5% of RA patients and followed a U-shaped distribution that had minimal prevalence at approximately 60 years of age. The prevalence was 30.4% in men and 32.0% in women," Wolfe reported.

At clinically significant levels, the prevalence of severe anemia (Hb<10 gm/dL) was 3.4% and the prevalence of mild anemia (Hb<11 gm/dL) was 11.1% in RA patients.

After erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) was the strongest predictor of anemia.

Wolfe also found that renal function is generally impaired in RA patients and that creatinine clearance is about 10 mm/hr lower in RA than in patients with noninflammatory rheumatic diseases.

The most important contributors to anemia in RA patients are iron-deficiency anemia (IDA) and anemia of chronic inflammation (ACI). Conventional tests such as iron, transferrin saturation, and ferritin are likely to underestimate the contribution of iron deficiency in RA patients, Ortho Biotech scientist Dr Mindy Yang reported. Using the newer serum-transferrin-receptor (sTfr) test, Yang found that iron deficiency was much more common than expected in RA patients with anemia, defined as Hb<11 gm/dL.

"Twenty-one of 24 (87.5%) of patients with ferritin of 30-100 ng/mL had an sTfr index of >1.5, consistent with iron deficiency," Yang said. "Surprisingly, 12 of 17 (70.6%) patients with ferritin >100 ng/mL also had an sTfr index of >1.5, suggesting functional iron deficiency in combination with ACI." Such patients are candidates for iron supplementation, and Yang found that four of eight patients who received oral or IV supplements had prompt improvements in sTfr index upon retesting.

"Testing with the sTfr index suggests that iron deficiency in RA is more common than previously reported and that even RA patients with ferritin consistent with ACI (>100 ng/mL) may also have functional iron deficiency," Yang said.