Ethnic differences in 25-year risk of incident chronic kidney disease among people with type 2 diabetes in New Zealand

Introduction Insights into ethnic differences in the natural history of chronic kidney disease (CKD) among people with type 2 diabetes mellitus (T2DM) might inform clinical strategies to address disparities in hospitalization and mortality. Risks of CKD II-V stages over a 25-year period between New Zealand Europeans (NZEs), Maori and Pasifika, and with T2DM in Auckland, New Zealand (NZ) were compared. Research design and methods As a primary care audit program in Auckland, the Diabetes Care Support Service was linked with national registration databases. People with existing CKD II-V were ruled out. To balance potential confounders, we applied a tapered matching method. 'Quasi-trial'-matched cohorts were set up separately between Maori and NZE and between Pasifika and NZE. Ethnic population differences in risk of any and each stage of CKD over 1994-2018 were examined by weighted Cox regression model. Results The HRs for developing any CKD, CKD stages II-V for Maori (n=2215) versus NZE (n=2028) were 1.18 (95% CI 0.99 to 1.41), 1.10 (95% CI 0.91 to 1.32), 1.70 (95% CI 1.19 to 2.43), 3.93 (95% CI 2.16 to 7.14), and 3.74 (95% CI 1.74 to 8.05), respectively. Compared with NZE (n=2474), the HRs for developing any CKD, CKD stages II-V for Pasifika (n=3101) were 1.31 (95% CI 1.09 to 1.57), 1.26 (95% CI 1.05 to 1.52), 1.71 (95% CI 1.14 to 2.57), 3.75 (95% CI 1.40 to 10.05), and 4.96 (95% CI 1.56 to 15.75), respectively. Conclusions Among people with T2DM in NZ, significant ethnic differences exist in the risk of progressing to each stage of CKD (stage V in particular). Mechanism studies underlying these differences, as well as the need for identification of biomarkers to predict the early onset renal lesion, are warranted.