Prevalence and Risk Factors for CKD Among Brickmaking Workers in La Paz Centro, Nicaragua

Abstract

Rationale & objective: In Central America, there is a high prevalence of chronic kidney disease (CKD) of nontraditional etiology often observed among agricultural workers. Few studies have assessed CKD prevalence among workers in nonagricultural occupations, which was the objective of this investigation.

Study design: Prospective cohort study.

Setting & participants: Male and female workers (n = 224) employed by artisanal brickmaking facilities in La Paz Centro, Nicaragua.

Predictors: Age, sex, education, smoking status, body mass index, alcohol consumption, water consumption, first-degree relative(s) with CKD, years worked, hours worked per week, job category, study visit (baseline and follow-up), and self-reported hypertension and diabetes.

Outcomes: CKD defined as estimated glomerular filtration rate (eGFR) < 60mL/min/1.73m² at 2 time points 4 months apart and CKD stage.

Analytical approach: A linear mixed-effects model with an unstructured covariance matrix was used to evaluate the association between demographics, occupational risk factors, and eGFR at baseline. The interaction between risk factors and time with change in eGFR was also evaluated. Multivariable logistic regression models were used to evaluate predictors of CKD.

Results: The CKD prevalence was 12.1% (n = 27), 100% of cases were male, 30% had stage 5 CKD (eGFR < 15mL/min/1.73m²), and 22% were younger than 35 years. Proportions of participants with eGFRs < 60mL/min/1.73m² at baseline and follow-up were 13.8% and 15.2%, respectively. Linear regression analysis demonstrated significant predictors of lower kidney function at baseline including oven work, older age, lack of education, and having an immediate family member with CKD. Predictors of CKD identified using logistic regression analysis included oven work and lack of education.

Limitations: Crude job classification measures, loss to follow-up, self-reported exposures.

Conclusions: The prevalence of CKD is high in this population of brick workers, suggesting that the epidemic of CKD affecting Mesoamerica is not limited to agricultural workers. These results are consistent with the hypothesis that occupational heat exposure is a risk factor for kidney disease in this region.

Keywords: CKDu; Chronic kidney disease (CKD); Mesoamerican nephropathy (MeN); Nicaragua; brickmaking; disease progression; estimated glomerular filtration rate (eGFR); etiology; heat exposure; heat stress; occupational hazard; risk factor; water consumption.