Nifedipine and mortality risk in the elderly: Relevance of drug formulation, dose and duration

Purpose - This study examines the risk of all-cause and cardiac-related mor tality associated with calcium channel blockers (CCBs) and other antihypert ensives/diuretics compared with beta-blockers among an elderly cohort. We e xplored variations in mortality risk according to CCB formulation, dose and duration of use. Methods - Data are from the clinical sample of the Canadian Study of Health and Aging, a population-based prospective study of community and instituti onal residing persons aged 65+ years. The sample comprised 837 subjects wit hout dementia and reporting use of 1+ antihypertensive/diuretic agents at b aseline (1991) and with survival data during follow-up (1996). Results - Risk of all-cause and cardiac-related mortality was significantly higher among nifedipine users (HR = 1.85, 95%CI 1.12, 3.05 and HR = 2.22, 95% Cl 1.02, 4.84, respectively) compared with beta-blocker users. After ad justing for covariates, the hazard ratios (95% confidence interval) for sel ected drug classes compared with beta-blockers were. nifedipine HR = 1.82 ( 1.09-3.04), diltiazem/verapamil HR = 0.96 (0.58-1.60), loop diuretics HR = 1.84 (1.21-2.82), ACE inhibitors HR = 0.98 (0.54-1.78) and other diuretics/ antihypertensives HR = 1.10 (0.70-1.72). Among nifedipine users, mortality risk increased with average daily dose and with recent (less than or equal to 6 months) initiation of therapy and remained significant for prolonged-a cting formulations. Conclusions - Older subjects exposed to the dihydropyridine calcium antagon ist nifedipine had a significantly higher risk for all-cause and cardiac-re lated mortality during the 5-year follow-up than subjects using beta-blocke rs. Copyright (C) 2000 John Wiley & Sons, Ltd.