Deterioration, improvement of kidney function over time and determinants in the Cape Town Bellville South cohort

Abstract

Aim: The aim of the present study was to assess the trajectories of glomerular filtration rate (GFR) and determinants of change during a 3-year period in free-living mixed-ancestry South Africans. Methods: In all 320 (78.1% women) adults, aged 56.2 years, from Cape Town were examined in 2008 and 2011. Estimated glomerular filtration rate (eGFR) was based on the Modification of Diet in Renal Disease model; and staging of eGFR used the National Kidney Foundation’s classification. Results: Mean eGFR (mL/min per 1.73 m2) was 68.6 at baseline and eGFR stages were: >90 (9.4%), 60–90 (58.7%), 30–60 (28.1%) and <30 (0.9%). eGFR increased by 8 mL/min during follow-up, reflecting variable trajectories by baseline eGFR stages, sex, hypertension and glucose tolerance (all P-interaction ≤0.012). Movements across eGFR stages during follow-up favoured improvement in 113 participants (35.3%), and worsened in 23 (7.2%). In adjusted multinomial logistic regressions, men had a 72% (43–86%) lower chance of improvement, while each mmHg higher systolic blood pressure conferred a 7% (3–11%) risk of deterioration. Equivalent for each 1% HbA1c was 30% (8–56%). Participants with glucose intolerance had 102% (3–297%) higher chances of improvement than diabetics. Conclusion: Variable trajectories of eGFR with time were observed in this cohort, reflecting the effects of modifiable risk factors such as hypertension and dysglycaemia.