Reverse Epidemiology of Hypertension-Mortality Associations in Hemodialysis Patients: A Long-Term Population-Based Study

BACKGROUND Although hypertension (HTN) is a predictor of mortality, recent data have questioned the link between baseline HTN and mortality in incident hemodialysis (HD) patients. We used Taiwan's National Health Insurance claim data (NHRI-NHIRD-99182) to investigate the association. METHODS In 1999, this longitudinal cohort study enrolled 5752 new HD patients. Follow-up began from the initiation of HD until death, the end of HD, or the end of 2008. A Kaplan―Meier survival analysis was done. Cox proportional hazard analysis was used to identify the risk factors for mortality. RESULTS The prevalence of baseline HTN was 75.47%. Patients with HTN had a higher prevalence of diabetic mellitus (DM) and cardiovascular diseases. The 1-, 5-, and 9-year cumulative survival rates were 95.5, 63.7 and 41.8% in patients with HTN, and 95.5, 71.0, and 52.0% in those without HTN (log-rank test: P <0.001). Multivariate analysis showed that patients with baseline HTN may have a higher survival rate (hazard ratio (HR) 0.901, 95% confidence interval (CI): 0.819―0.992). After stratification by age and DM, only elderly (≥65) patients without DM had a significantly higher survival rate (HR 0.769, 95% CI: 0.637―0.927). HTN predicts lower mortality with increasing age in patients with congestive heart failure (CHF) or coronary artery disease (CAD). CONCLUSIONS There is a reverse (counterintuitive) association between baseline HTN and mortality in elderly HD patients without DM and a clear tendency for a reverse association with increasing age in patients with CHF or CAD. Further study of the association between HTN and mortality in older HD patients may be warranted.