Background: Ethnic differences in chronic kidney disease (CKD) progression are not well characterized but are of interest across and within countries.
Methods: We followed up a large CKD cohort of patients of three different ethnic origins [Caucasian, Oriental Asian (OA) and South Asian (SA)] from time of nephrology referral in a universal health care system. Key outcomes were time to death and/or renal replacement therapy (RRT) and rate of decline in estimated GFR (eGFR). The effects of known predictors (blood pressure, proteinuria, age, sex, diabetes, cardiovascular disease and medications) and of other laboratory abnormalities were assessed using multivariate modelling techniques, including both Cox proportional hazards and competing risk approach.
Results: The cohort comprised 3444 patients (2626 Caucasians, 397 OA and 421 SA). All-cause mortality rates are higher in Caucasians than SA or OA [hazard ratio (HR) 0.693 and 0.803, P < 0.05]. OA and SA have higher risks of progressing to RRT (HR 1.281 and 1.349, P < 0.05) and lower risks of death before RRT (HR 0.718 and 0.520, P < 0.05) compared to Caucasians after adjustment for usual risk factors. However, when adjusted for additional laboratory abnormalities, differences did not persist for progression, but did for survival advantage of Asians. The median rate of decline in eGFR (in millilitres per minute per 1.73 m(2)) was significantly slower in Caucasians (-2.11) than in OA (-2.93) or SA (-3.56), P = 0.027.
Conclusions: Asians appear to have faster CKD progression and lower mortality rates compared to Caucasians. This effect is not explained by the usual variables, but rates of progression may be related to differences in severity of laboratory abnormalities at different CKD stages. Further research is needed to understand the implications of these findings.