Associations between arsenic in drinking water and occurrence of end-stage renal disease with modifications by comorbidities: A nationwide population-based study in Taiwan

Arsenic may affect the function of proximal convoluted tubules and glomeruli, but epidemiological data on the association between arsenic ingestion and end-stage renal disease (ESRD) are limited. Therefore, we conducted a nationwide population-based study in Taiwan, where the incidence of ESRD is the highest in the world, to study the potential association. Using the National Health Insurance Database in Taiwan, we constructed a cohort of 362,505 members with age ≥ 40 years in 1998. We identified patients of ESRD newly diagnosed between January 1, 1998 and December 31, 2010 and performed Cox proportional hazard regressions to identify risk factors for ESRD and evaluate their effects. Arsenic levels in drinking water were assessed on the basis of a nationwide census survey conducted by the government, of which measurement reports were available for 311 townships. We identified 5442 new patient of ESRD during the study period and found that residents of areas with arsenic levels ≥ 50 μg/L in the drinking water had a hazard ratio (HR) of 1.14 (95% confidence interval [CI]: 1.08–1.21) for ESRD. After adjusting for sex, age, income, and comorbidities, we found an adjusted HR of 1.12 (95% CI: 1.06–1.19), which was still statistically significant. Furthermore, the effect was modified by comorbidities, with more prominent effects on patients with less than three comorbidities (adjusted HR = 1.51; 95% CI: 1.22–1.86 for low comorbidity score). In conclusion, a high arsenic level in drinking water was a risk factor for ESRD, independent of other documented risk factors. Reducing high-risk comorbidities in patients with early-stage renal dysfunction is important for slowing the progression of the disease to ESRD, even in the endemic area of arsenic exposure.