Abstract / Summary
Abstract Background Chronic kidney disease of unknown etiology (CKDu) has emerged as a significant public health problem among disadvantaged populations engaged in physically demanding occupations in tropical regions. Evidence on CKDu among small-scale fishing communities in sub-Saharan Africa remains limited. This study estimated the prevalence of reduced kidney function suggestive of CKDu and identified associated factors among small-scale fishers in Northwest Tanzania using the Disadvantaged Populations eGFR Epidemiology (DEGREE) protocol. Methods A community-based cross-sectional study was conducted among 422 small-scale fishers in Northwest Tanzania. After applying the DEGREE protocol age criterion, 379 participants aged 18–59 years were eligible for further analysis. Kidney function was estimated using the 2021 CKD-EPI creatinine equation. Participants with hypertension, diabetes mellitus, or heavy proteinuria were excluded to identify reduced kidney function not explained by common causes of chronic kidney disease; a modified DEGREE analysis additionally excluded participants living with HIV. Multivariable linear regression was used to assess factors associated with continuous eGFR, while multivariable logistic regression examined factors associated with reduced kidney function (eGFR < 60 mL/min/1.73 m²). Sensitivity analyses assessed the potential influence of dehydration, urinary tract infection, haematuria, and urogenital schistosomiasis. Results The prevalence of reduced kidney function was 16.6% in the overall population, 13.8% in the DEGREE subset, and 13.6% after additionally excluding participants living with HIV. In multivariable analyses, increasing age was consistently associated with lower continuous eGFR and higher odds of reduced kidney function, whereas male sex was independently associated with higher eGFR and lower odds of reduced kidney function. Occupational heat exposure, dehydration, daily working hours, body mass index, Schistosoma haematobium infection, sugary drink consumption, and energy-drink consumption were not independently associated with kidney function. Sensitivity analyses showed stable prevalence estimates after excluding participants with urinary abnormalities suggestive of acute kidney insults. Conclusions Reduced kidney function suggestive of a CKDu-compatible phenotype was relatively common among small-scale fishers in Northwest Tanzania. The persistence of elevated prevalence after excluding conventional causes suggests that other locally relevant occupational, environmental, infectious, biological, or socioeconomic factors may contribute. Because kidney function was measured once, CKDu could not be confirmed. Longitudinal studies with repeated kidney-function measurements and objective exposure assessment are needed.