Chronic kidney disease burden attributable to heat waves amid climate change and related hospital accessibility: a health impact assessment study based on two nationally representative surveys in China

Background: Heat waves are increasingly recognized as an environmental determinant of chronic kidney disease (CKD). However, the CKD burden attributable to heat waves and associated healthcare inequalities, particularly under future climate change, remains insufficiently characterized. Methods: Based on two nationally representative cross-sectional surveys in China, we established climate region-specific exposure-response functions between heat waves and CKD. Then, we conducted 1-km grid-level health impact assessments integrating the most up-to-date nationally representative CKD prevalence data, temperature projections, population estimates, and socioeconomic indicators. The analyses focused on stages 4–5 CKD (advanced CKD), given its progressive nature and requirements for continuous medical treatment. Heat wave-attributable CKD burden was quantified as attributable cases (ACs), attributable fractions (AFs), and population attributable fractions (PAFs). Projections for 2030–2090 were generated under multiple Shared Socioeconomic Pathways (SSPs). Hospital accessibility was evaluated using AC-weighted driving times and accessibility scores, with inequality assessed via Gini indices and Lorenz curves. Results: In 2020, an estimated 491,362 (227,772–694,191) stages 4–5 CKD cases (about 30.06% of all cases and 45.31 per 100,000 adults) were attributable to heat waves, disproportionately affecting rural areas (PAF: 47.08 per 100,000) and subtropical and tropical regions (PAF: 52.43 per 100,000) compared to their counterparts. Projections indicated increasing trends in PAFs under high-emission scenarios (e.g., SSP5-8.5 showing > 2-fold increase in 2090). The average driving time to the nearest hospital for ACs was 15.8 (7.6–22.3) minutes, with rural areas showing significantly longer times (20.4 min) and lower accessibility. The national Gini index for hospital accessibility was 0.45, indicating high inequality, and the inequality might persist across all future climate scenarios. Conclusions: Heat waves are associated with a substantial and spatially uneven burden of advanced CKD in China, compounded by significant inequalities in hospital accessibility. These inequalities may persist under future climate change given current hospital accessibility settings. Clinical trial number: Not applicable.