Ethnic differences in creatinine kinetics in a New Zealand end-stage kidney disease cohort.

BACKGROUND Recent data have suggested that glomerular filtration rate (GFR) is better predicted in New Zealand (NZ) Māori and Pacific People using the equations for Black people that predict higher GFR for any given serum creatinine. We hypothesized that this might be due to a higher rate of creatinine generation in NZ Māori and Pacific People. AIM To compare creatinine kinetics between different ethnic groups in a cohort of NZ peritoneal dialysis patients. METHODS In this retrospective single-centre observational study, creatinine kinetics in 181 patients were determined from timed serum samples, peritoneal dialysate and urine collections between 1 October 2004 and 31 July 2011. Ethnicity was classified as Asian, NZ European, NZ Māori and Pacific People. RESULTS A total of 799 samples from 181 patients were analysed: 194 in Asians, 127 in NZ Europeans, 268 in NZ Māori, 207 in Pacific People. Pacific People had the highest serum creatinine and lean body mass, and the highest creatinine generation rate at 1349 mg/day, compared with 1049 for Asians, 1186 for NZ Europeans and 1094 for NZ Māori (P = 0.0001). After adjustment for confounding factors, Pacific People had a greater creatinine generation by 140 mg/day compared with NZ Europeans (P = 0.047). CONCLUSION Pacific People on peritoneal dialysis in NZ have higher serum creatinine, lean body mass and creatinine generation than other ethnic groups. This is consistent with previous observations that equations for predicting GFR in Black people may have increased accuracy in some Australasian non-White non-Asian populations.