Renal function, erythropoietin, and anemia of older persons: the InCHIANTI study.

BACKGROUND: In the older population, anemia has been associated with poor outcomes including disability and mortality. Understanding the mechanisms leading to anemia is essential to plan better treatment and prevention strategies. We tested the hypothesis that the age-related decline in kidney function is associated with an increased prevalence of anemia and that such an increase is accompanied by a concomitant decrement in erythropoietin levels.

METHODS: Data were from the InCHIANTI study, a population-based study performed in a sample of community-dwelling older (> or = 65 years) persons living in Italy. This analysis included 1005 participants with complete data on hemoglobin and erythropoietin levels and markers of renal function.

RESULTS: The prevalence of anemia according to the World Health Organization criteria (hemoglobin level < 12 g/dL for women and < 13 g/dL for men) was 12.0% and increased with age in both sexes. After adjusting for age, diseases, and other confounders, only participants with a creatinine clearance (CrCl) of 30 mL/min or lower (< or = 0.50 mL/s) had a higher prevalence of anemia compared with those with a CrCl higher than 90 mL/min (> 1.50 mL/s) (P<.01). Consistently, participants with a CrCl of 30 mL/min or lower (< or = 0.50 mL/s) had significantly lower age- and hemoglobin-adjusted erythropoietin endogenous levels. After excluding men and women with CrCl of 30 mL/min or lower (< or = 0.50 mL/s) and adjusting for confounders, we found a trend toward an increase in prevalence of anemia with decreasing renal function; however, it was not statistically significant.

CONCLUSIONS: Severe age-related decline in renal function is associated with a reduced erythropoietin secretion and anemia. Whether moderate kidney impairment in older persons is associated with a progressively increasing risk of anemia remains to be determined.