Prevalence of and risk factors for chronic kidney disease of unknown aetiology in India : Secondary data analysis of three population-based cross-sectional studies

Objectives To assess whether chronic kidney disease of unknown aetiology (CKDu) is present in India and to identify risk factors for it using population-based data and standardised methods. Design Secondary data analysis of three population-based cross-sectional studies conducted between 2010 and 2014. Setting Urban and rural areas of Northern India (states of Delhi and Haryana) and Southern India (states of Tamil Nadu and Andhra Pradesh). Participants 12 500 individuals without diabetes, hypertension or heavy proteinuria. Outcome measures Mean estimated glomerular filtration rate (eGFR) and prevalence of eGFR below 60 mL/min per 1.73 m 2 (eGFR <60) in individuals without diabetes, hypertension or heavy proteinuria (proxy definition of CKDu). Results The mean eGFR was 105.0±17.8 mL/min per 1.73 m 2. The prevalence of eGFR <60 was 1.6% (95% CI=1.4 to 1.7), but this figure varied markedly between areas, being highest in rural areas of Southern Indian (4.8% (3.8 to 5.8)). In Northern India, older age was the only risk factor associated with lower mean eGFR and eGFR <60 (regression coefficient (95% CI)=a '0.94 (0.97 to 0.91); OR (95% CI)=1.10 (1.08 to 1.11)). In Southern India, risk factors for lower mean eGFR and eGFR