Surface water quality and chronic kidney disease burden in China, Canada, and Ireland: an exploratory ecological panel study

Aim: Chronic kidney disease (CKD) is a major global health burden. Emerging evidence links water quality with kidney outcomes, but ecological panel evidence remains limited and context dependent. We examined hypothesis-generating associations between surface water quality indicators and CKD burden in China, Canada, and Ireland during 2010–2017. Methods: We integrated age-standardized CKD rates from the Institute for Health Metrics and Evaluation (IHME) GBD Results Tool (DALYs, deaths, incidence, prevalence, years lived with disability (YLDs), and years of life lost (YLLs) per 100,000 population; country-year estimates were restricted to 2010–2017) for China, Canada, and Ireland with 284,965 surface water quality observations. The downloaded IHME citation identified the release as Global Burden of Disease Study 2023 (GBD 2023) Results, while the estimates used in this analysis were limited to 2010–2017. Country-specific ordinary least-squares regression was used for the primary analysis; random-effects meta-analysis was used only to summarize country-specific estimates, and restricted cubic spline (RCS) analyses explored non-linear patterns. Standardized beta coefficients were added to improve comparability across countries and water-quality scales. Results: CKD DALYs rates declined in China (–13.5%) and Ireland (–5.4%) but rose in Canada (+9.0%). In country-specific models, nitrate was inversely associated with CKD DALYs (beta = –12.10; 95% CI: –19.80 to –4.41; P = 0.002; standardized beta = –0.25) and deaths (beta = –0.94; P = 0.006; standardized beta = –0.26) in Ireland. Total nitrogen was inversely associated with CKD incidence in Canada (beta = –0.63; P = 0.006; standardized beta = –0.20). These associations occurred over narrow exposure ranges and should be interpreted cautiously. Random-effects pooled estimates were not statistically significant, and heterogeneity across outcomes ranged from none to substantial (I2: 0–78.4%). Conclusions: Surface water nitrate and nitrogen showed inconsistent, country-specific associations with CKD burden and did not yield robust pooled estimates. These hypothesis-generating ecological findings underscore the need for individual-level studies with measured drinking-water exposure, harmonized diagnostic information, and latency-aware designs.