Incidence and Associations of Chronic Kidney Disease in Community Participants With Diabetes: A 5-Year Prospective Analysis of the EXTEND45 Study.

OBJECTIVE: To determine the incidence of and factors associated with an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 in people with diabetes.

RESEARCH DESIGN AND METHODS: We identified people with diabetes in the EXamining ouTcomEs in chroNic Disease in the 45 and Up Study (EXTEND45), a population-based cohort study (2006-2014) that linked the Sax Institute's 45 and Up Study cohort to community laboratory and administrative data in New South Wales, Australia. The study outcome was the first eGFR measurement <60 mL/min/1.73 m2 recorded during the follow-up period. Participants with eGFR < 60 mL/min/1.73 m2 at baseline were excluded. We used Poisson regression to estimate the incidence of eGFR <60 mL/min/1.73 m2 and multivariable Cox regression to examine factors associated with the study outcome.

RESULTS: Of 9,313 participants with diabetes, 2,106 (22.6%) developed incident eGFR <60 mL/min/1.73 m2 over a median follow-up time of 5.7 years (interquartile range, 3.0-5.9 years). The eGFR <60 mL/min/1.73 m2 incidence rate per 100 person-years was 6.0 (95% CI 5.7-6.3) overall, 1.5 (1.3-1.9) in participants aged 45-54 years, 3.7 (3.4-4.0) for 55-64 year olds, 7.6 (7.1-8.1) for 65-74 year olds, 15.0 (13.0-16.0) for 75-84 year olds, and 26.0 (22.0-32.0) for those aged 85 years and over. In a fully adjusted multivariable model incidence was independently associated with age (hazard ratio 1.23 per 5-year increase; 95% CI 1.19-1.26), geography (outer regional and remote versus major city: 1.36; 1.17-1.58), obesity (obese class III versus normal: 1.44; 1.16-1.80), and the presence of hypertension (1.52; 1.33-1.73), coronary heart disease (1.13; 1.02-1.24), cancer (1.30; 1.14-1.50), and depression/anxiety (1.14; 1.01-1.27).

CONCLUSIONS: In participants with diabetes, the incidence of an eGFR <60 mL/min/1.73 m2 was high. Older age, remoteness of residence, and the presence of various comorbid conditions were associated with higher incidence.