Rest, shade, hydration and hygiene for the prevention of kidney injuries and inflammation in a Nicaraguan sugarcane worker cohort.

Abstract

To study the effect of a progressively enhanced rest-shade-hydration-hygiene (RSHH) intervention on kidney injury and inflammation biomarkers, and rates of clinical acute kidney injury (AKI) in Nicaraguan sugarcane workers with a very high rate of chronic kidney disease of non-traditional origin (CKDnt). We analysed serum creatinine and C-reactive protein (CRP) and leukocyturia from samples obtained before and at the end of four harvest seasons (H1-4). An increase in creatinine≥0.30 mg/dL over the harvest was considered incident kidney injury (IKI). Rates of clinically diagnosed AKI were obtained from medical records. Each season the RSHH intervention included progressively longer and more frequent rest periods with improved access to shade and hydration, implementation monitoring, qualitative interviews and health outcome assessments. 1044 workers were followed for 1938 person-harvests. Among burned cane cutters, the job group with the highest workload and worst outcomes initially, there were decreasing rates of IKI (21% in H1 to 1% in H4, p<0.01), AKI (20/1000 worker-months to 8/1000 worker-months, p<0.01) and end-harvest leukocyturia (26% to 1%, p<0.01), and less rise in cross-harvest CRP (median 1.75-fold increase in H1 to 1.00 in H4, p<0.01). Kidney outcomes among outdoor heat-stressed workers at high risk of CKDnt improved as a structured RSHH intervention was implemented and committed to by workplace management. The findings support a causal relationship between occupational heat stress, kidney injury and CKDnt and point to possibilities for prevention.