The effect of anemia treatment on selected health-related quality-of-life domains: a systematic review.

BACKGROUND: Anemia is a reduction in the oxygen-carrying capacity of red blood cells that results in a variety of symptoms, including dyspnea, headaches, light-headedness, and fatigue. Although anemia has been associated with reduced health-related quality of life (HRQoL), its treatment has not yet been consistently shown to improve HRQoL.
OBJECTIVE: This systematic review of the literature was conducted to determine whether the treatment of anemia improves HRQoL domains, regardless of the type of underlying disease.
METHODS: Data for this review were drawn from the clinical trial databases from 2 previous systematic literature reviews of erythropoiesis-stimulating protein treatment for renal insufficiency- and cancer-related anemia, both spanning the period January 1, 1980, through December 31, 2001. MEDLINE, Cancerlit, and Current Contents/Clinical Medicine were searched using the combined terms erythropoietin, kidney failure, neoplasms, and anemia. The reference lists of all identified articles were searched manually for additional relevant papers. The review included prospective studies that reported both HRQoL and hematocrit (Hct) in patients with cancer or renal insufficiency who received treatment for anemia with an erythropoiesis-stimulating protein. HRQoL was categorized by domain (overall, energy/fatigue, physical, activity); changes in HRQoL domains were expressed as effect sizes and meta-analyzed, as were correlation coefficients. The effects on HRQoL of dropout rate, study duration, baseline Hct, and change in Hct were examined in meta-regression analyses.
RESULTS: Sixteen studies each were identified in patients with renal insufficiency (N = 2253) and patients with cancer (N = 10,695). The treated groups included 11,710 patients, and the control groups included 1238 patients. The baseline Hct in all treated groups averaged 26.0%: 28.3% in the group with cancer and 24.4% in the group with renal insufficiency. The mean improvement in Hct from baseline to the end of treatment was 8.3% (range, 1.0%-16.5%) in treated patients and 1.0% (range, 0.0%-3.3%) in controls. The Hct changes were similar in treated patients with cancer and treated patients with renal insufficiency, as was the HRQoL effect size (0.43). Dropout rate and study duration were not significant predictors of HRQoL changes, but change in Hct was a significant predictor in both conditions. Meta-analysis of the correlation coefficients, adjusting for HRQoL domains, showed a consistent and significant positive correlation between change in Hct and change in HRQoL (P < 0.001).
CONCLUSION: The consistency in both direction and magnitude of effect across many studies and thousands of patients supports the hypothesis that treatment of anemia with erythropoiesis-stimulating protein improves selected HRQoL domains in patients with renal insufficiency- or cancer-related anemia.