CKDu-AGRI Study-a population-based cross-sectional study of chronic kidney disease and chronic kidney disease of unknown aetiology among agricultural workers in Tamil Nadu, India.

Abstract

Chronic kidney disease of unknown cause (CKDu) has been reported in "hotspots" around the world and linked to occupational heat stress, exposure to agrochemicals and environmental toxins. This was a systematic, statewide, population-based, observational study of agricultural workers in Tamil Nadu, to estimate the prevalence of chronic kidney disease (CKD) and CKDu. The state of Tamil Nadu was divided into five agroclimatic zones and stratified multi-stage cluster sampling was performed to select a representative study population. All participants underwent clinical evaluation and laboratory testing (Phase 1). Repeat sampling was performed after 3 months for all individuals with an eGFR <60 mL/min per 1.73 m² during initial sampling (Phase 2). Among 3350 participants who were screened, the number of participants with eGFR ≤60 mL/min per 1.73 m² at the end of Phase 1 and Phase 2 were 584 and 178, respectively. The overall prevalence of CKD was therefore 5.31% (95% CI 4.58-6.13), with the prevalence of CKDu being 2.66% (95% CI 2.14-3.26). The factors that were significantly associated with CKD were increased age, diabetes, hypertension, absence of formal education, anaemia, smokeless tobacco use, and weekly hours of outdoor work. Notably, 406 participants with an eGFR ≤60 mL/min per 1.73 m² during Phase 1 had a normal eGFR when re-measured during Phase 2. These episodes of transient subclinical AKI could potentially contribute to CKD. The prevalence of CKD among agricultural workers in Tamil Nadu is 5.31%, with about half of these due to CKDu. The effect of transient subclinical AKI on CKD progression needs further study. Tamil Nadu Health System Reform Program, Department of Health and Family Welfare, Government of Tamil Nadu.