Aims: To investigate the association between estimated glomerular filtration rate (eGFR) and total and cardiovascular mortality in a population-based cohort of diabetic subjects.
Methods: A longitudinal study using a population-based district diabetes register comprising 3288 subjects in South Tees, UK. The eGFR was calculated using the Modification of Diet in Renal Disease (MDRD) study equation. Patients were stratified by baseline eGFR into five stages as per the National Kidney Foundation guidelines: Stage 1, eGFR > 90; Stage 2, eGFR 60-89; Stage 3, eGFR 30-59; Stage 4, eGFR 15-29; and Stage 5, eGFR < 15 ml/min per 1.73 m(2). Main outcome was all-cause and cardiovascular mortality between 1 January 1994 and 31 July 2004.
Results: At baseline, mean age (58.4 years) differed between groups. Persons with lower eGFR were older (P < 0.001). Thirty-six percent (n = 1193, males 56%) had died by 10 years (cardiovascular cause in 60%). Median follow-up was 10.5 years amounting to 28 342 person years. Stages 4 and 5 (eGFR <or= 29 ml/min per 1.73 m(2)) were amalgamated for mortality analysis. Total and cardiovascular mortality increased with reduced eGFR. Adjusted hazard ratios (HR) [95% confidence interval (CI)] for all-cause mortality comparing groups 2 and 3, and 4 and 5 combined with group 1 were 1.28 (1.02, 1.60), 2.58 (2.05, 3.25) and 6.42 (4.25, 9.71), respectively. Adjusted HRs (95% CI) for mortality due to circulatory disease comparing groups 2 and 3, and 4 and 5 combined with group 1 were 1.50 (1.10, 2.06), 3.32 (2.41, 4.58) and 7.99 (4.69, 13.62), respectively.
Conclusions: In diabetic subjects, mortality increases significantly with reduced GFR. Low eGFR identifies patients at high risk of cardiovascular mortality who should be targeted for aggressive risk factor modification.