Physically strenuous work in a hot climate and reduced kidney function in the sugarcane industry

Abstract

Background and aim: Sugarcane workers are reportedly at increased risk of chronic kidney disease of non-traditional causes (CKDnt). Most prior studies have focused on a limited number of jobs, yet suspected risk factors of hot climatic conditions and strenuous work are common across jobs in the industry. We examined whether reduced kidney function was associated with working in hot climatic conditions and strenuous work in an industry-wide program. Methods: Data from a surveillance program at a Nicaraguan sugarcane planation 2015-2020 involved random collection of blood, allowing estimation of glomerular filtration rate (eGFR), for all employees. Any eGFR <=60 mL/min/1.73m2 was classified as low. Jobs were classified by whether outside and whether physical labor. Analyses restricted to males <50 years old who were non-supervisors. Multivariable models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs) comparing odds of low eGFR for working outside with inside, either adjusted for or stratified by age. Among outside workers, odds of low eGFR for each laborer job was compared with non-laborers. Models also adjusted for repeated measures and harvest period. Results: Analyses included 2,884 employees with 6,144 eGFR measures. There was no difference in odds of low eGFR between working outside or inside. Among those outdoors, laborers had increased odds of low eGFR compared with non-laborers (OR=3.58, (95% CI 1.85-6.94)). The association was most pronounced among those <=30 years old (OR=11.89 (95% CI 1.68-84.03)). Jobs of seed loader, seeder/reseeder, and weeder had >=6-fold increased odds of low eGFR relative to outdoor non-laborers (p<0.001). Conclusions: Physically strenuous jobs in combination with working outside in a hot climate was consistently associated with reduced kidney function, with strongest influence in younger workers. Our results suggest more research should evaluate younger workers in physically demanding jobs to help identify prevention strategies. Keywords: CKDnt, heat, work