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Chronic kidney disease of unknown etiology (CKDu) is a CKD sub-type that disproportionately affects agricultural communities in warmer, tropical climates globally and lacks traditional risk factors for CKD. The Co-Benefits of Largescale Organic Farming On HuMan Health (BLOOM) study is a cluster randomized trial that is being conducted in a suspected hotspot of CKDu. We aimed to describe the baseline kidney function among BLOOM participants, with comparisons to another population-based study conducted in both agricultural and urban settings in Northern and Southern India (‘UDAY’ meaning dawn in Sanskrit). Since estimated glomerular filtration (eGFR < 60 ml/min/1.73m2) is a late threshold of kidney disease, we plan to focus instead on the distribution of eGFR, and whether it differs by region of residence.
Kidney function was analyzed in adults (18-44 years) from 8 communities in India. UDAY (n=2138) collected data from 4 sites in both agricultural and urban settings in Sonipat, Haryana (North India) and Visakhapatnam (‘Vizag’), Andhra Pradesh (South India) starting in 2014. BLOOM (n=1592) collected data from agricultural households for 3 months from August to October 2022 from 4 districts in Andhra Pradesh which also included Vizag. Both studies used IDMS-calibrated creatinine assays. We compared CKD EPI (2009) eGFR by men versus women, north versus south, and urban versus rural and used the Wilcoxon-rank sum test. We present age and sex-stratified distribution of eGFR by these geographical subclassifications.
Men had lower median eGFR (indicating worse kidney function) than women across both rural and urban areas in UDAY (107.0 versus 110.3 mL/min/1.73m2, p < 0.01) and in BLOOM (87.4 versus 89.9 mL/min/1.73m2,, p < 0.01). Both men and women in rural areas had lower eGFR than their counterparts in urban areas. BLOOM participants had the lowest eGFR for both men and women.
Conclusions
Our preliminary analyses suggest that there is a population-based difference in eGFR distribution based on location, with participants in southern agricultural communities having lower eGFR than urban areas in the same geography and lower eGFR than northern rural or urban areas. Finally, the BLOOM study had the lowest eGFR for both men and women.