Risk factors for all-cause and cause-specific mortality in patients with chronic kidney disease: age-specific associations and attributable burden

Introduction Evidence regarding age-specific associations between risk factors and mortality in patients with chronic kidney disease (CKD) remains limited. We sought to investigate these age-specific associations and to measure their attributable burden on mortality. Methods This population-based, retrospective cohort study included 576,677 patients in Hong Kong (73.5 ± 13.8 years, 2008–2020). We assessed all-cause and seven cause-specific mortality. Risk factors included six modifiable risk factors (smoking, blood pressure, fasting blood glucose/hemoglobin A1c, low-density lipoprotein cholesterol [LDL-C], and body mass index) and four major comorbidities (diabetes, cardiovascular disease [CVD], heart failure, and cancer). Using hazard ratios and population-attributable fractions (PAFs), we compared the associations and mortality burden of these risk factors across five age groups (18 to ≥85 years). Results During a median follow-up of 4.8 years, 329,098 (57.1%) patients died, with primary death causes being CVD (9.9%), cancer (9.9%), and kidney diseases (4.7%). Despite a higher absolute mortality risk in older patients, the relative risk of most risk factors declined with age. Collectively, all risk factors accounted for a higher mortality proportion in the youngest group (PAF: 44.3% [95% confidence interval: 35.3%, 52.0%]) than in the oldest group (22.6% [14.6%, 29.7%]). For patients aged 18-54, suboptimal LDL-C control (12.0% [8.0%, 15.8%]) was the leading risk factor, while CVD (12.6% [12.1%, 13.1%]) was the most influential factor in patients aged ≥75. Conclusion The evaluated risk factors were associated with increased relative mortality risks in younger CKD patients. These findings underscore the importance of early management strategies, emphasizing LDL-C control in younger and CVD prevention in older CKD patients.