Renal impairment and anaemia in a population-based study of older people

Established renal failure is a known cause of anaemia. However, the association between more modest levels of renal impairment and anaemia is unclear.

The aim of the present study was to investigate the association between mild renal impairment and anaemia in the general population.

A population-based, cross-sectional study was conducted in the general community in an urban area of the Blue Mountains, just west of Sydney, Australia. The study included 3222 people aged > or =49 years (mean age 65 years). Serum creatinine and haemoglobin were measured using standard laboratory techniques. Creatinine clearance was estimated from serum creatinine, body weight, sex and age.

Two hundred and seventy subjects (8.4%) had serum creatinine levels > or =125 micromol/L and estimated -creatinine clearances were <0.84 mL/s (50 mL/min) in 894 subjects (27.7%) and <0.50 mL/s (30 mL/min) in 120 subjects (3.7%). There was a strong association between reduced renal function and anaemia. Compared to those with serum creatinine <125 micromol/L, the age-adjusted relative risk (RR) of anaemia in women (haemoglobin <12.0 g/dL) with serum creatinine > or =125 micromol/L was 5.5 (95% confidence interval (CI) 2.9-10.7) and the RR of anaemia in men (haemoglobin < 13.0 g/dL) was 3.1 (95% CI 1.6-6.0). Estimated -creatinine clearance <50 mL/min was associated with a three-fold increased risk of anaemia in women and a five-fold increased risk in men.

The results of the present study suggest that even modestly impaired renal function is associated with anaemia in older men and women. The possibility of renal impairment should be considered in the diagnosis and management of anaemia in people aged>50 years.