Association of reduced kidney function with cardiovascular disease and mortality in elderly patients: comparison between the new Berlin initiative study (BIS1) and the MDRD study equations

Background New creatinine based equations for estimating glomerular proposed for aged subjects have not been assessed in their association of reduced eGFR with cardiovascular (CV) morbidity or all cause (AC) mortality. Patients All subjects >= 70 years old (2998) who had been admitted to the hospital during a 12 month period were examined. Methods In a cohort study we applied the new Berlin Initiative Study (BIS1) equation. We compared the association of reduced eGFR estimated by BIS1 and MDRD equations, with cardiovascular (CV) disease and all cause (AC) mortality. Results eGFR was 57 +/- 17 mL/min/1.73 m(2) by MDRD and 71 +/- 28 mL/min/1.73 m(2) by BIS1 (P < 0.001). A diagnosis of CV disease was present in 947 patients. CV disease was associated with eGFR < 60 mL/min/1.73 m(2) by both formulas: OR 1.179 (CI 1.001-1.390) for BIS1 and OR 1.440 (CI 1.223-1.696) for MDRD. In survival analysis a significant association of eGFR < 60 mL/min/1.73 m(2) with AC mortality was found for both equations: MDRD (HR = 1.270, CI 1.111-1.453, P < 0.001), BIS1 (HR = 1.174, CI 1.031-1.338, P = 0.016). The analysis repeated with groups of age showed that the association of mortality with eGFR(BIS1) < 60 mL/min/1.73 m(2) was lost over 80 years. Conclusions In patients > 70, admitted to hospital, the implementation of the new BIS1 estimating equation does not modify the relationship, observed with the MDRD formula, of reduced GFR with CV disease or AC mortality.