The Synergistic Relationship Between Estimated GFR and Microalbuminuria in Predicting Long-term Progression to ESRD or Death in Patients With Diabetes: Results From the Kidney Early Evaluation Program (KEEP)

Abstract

Chronic kidney disease may complicate diabetes, often manifesting with reduced glomerular filtration rate (GFR), albuminuria, or both. Although greater albuminuria and lower estimated GFR both predict adverse prognosis, whether a synergistic prognostic interaction occurs in patients with diabetes has not been defined in a large national cohort study. We used 2000-2011 data from the National Kidney Foundation's Kidney Early Evaluation Program (KEEP) for 42,761 participants with diabetes. Kaplan-Meier survival analysis and multivariable Cox regression were used to ascertain the association of estimated GFR, albumin-creatinine ratio (ACR), and their interaction on all-cause mortality and progression to end-stage renal disease (ESRD) at a median 4 years of follow-up. Of 42,761 participants with diabetes, 8,618 (20.2%) had estimated GFR <60 mL/min/1.73 m(2), 7,715 (18.0%) had ACR >30 mg/g, and 2,641 (6.2%) had both. The unadjusted incidence (per 1,000 person-years) of all-cause mortality increased from 3.1 (95% CI, 2.4-3.8) in participants with estimated GFR ≥ 105 mL/min/1.73 m(2) and no albuminuria to 73.7 (95% CI, 54.9-92.5) in participants with estimated GFR <30 mL/min/1.73 m(2) and macroalbuminuria (P < 0.001). Progression to ESRD likewise increased from 0.2 (95% CI, 0-0.4) to 220.4 (95% CI, 177.2-263.6) per 1,000 person-years (P < 0.001). After adjustment for confounders, both estimated GFR and albuminuria were associated independently with mortality and progression to ESRD, with a strong synergistic interaction (P for interaction < 0.001); estimated GFR <30 mL/min/1.73 m(2) and macroalbuminuria together were associated with a 5-fold higher risk of mortality and a more than 1,000-fold higher risk of progression to ESRD (compared with patients with estimated GFR >60 mL/min/1.73 m(2) and ACR <30 mg/g; P < 0.001 for both outcomes). In this large cohort of diabetic KEEP participants with more than 170,000 person-years of follow-up, both estimated GFR and albuminuria were associated independently with mortality and progression to ESRD, with a strong synergistic interaction.