Objective: A case control study has reported a 60% higher risk of myocardial infarction in hypertensives treated with a calcium channel blocker (CCB). We examined the Department of Health Hypertension Care Computing Project (DHCCP) data to see if we could confirm or refute this suggestion.
Design: Two case control studies, matched and unmatched, plus two longitudinal studies from 1 year of presentation, one for all subjects given a CCB for more than 1 year compared with those not given this drug, and the second comparing survival on the different drugs initially given between 3 and 12 months of follow-up.
Subjects: A total of 9328 subjects were included in the analyses and 2154 died. Of these, 6406 received one or more of the following index drugs: 26% a calcium channel blocker (CCB); 84% a diuretic; 29% alpha methyldopa; 12% a beta-blocker (BB); and 11% an angiotensin-converting enzyme (ACE) inhibitor. The CCBs were nifedipine, diltiazem or verapamil.
Results: In the case control studies a group given diuretics +/- other treatments (but not including one of the index drugs) provided a reference group with a relative risk (RR) of 1.0. In the matched case control study the adjusted RR for a CCB without a diuretic was 1.32 (95% CI 0.64-2.70) for IHD mortality and 1.05 (95% CI 0.60-1.84) for cardiovascular mortality. Similar results were observed for methyldopa, BBs and ACE inhibitors. The results in the unmatched case control analysis were also similar. The longitudinal study comparing all those treated for over 1 year with a CCB with all other treatments showed a RR for total mortality of 1.03 (95% CI 0.85-1.25). The longitudinal study of total mortality according to treatment initiated at 3-12 months found results of a similar magnitude for CCBs, methyldopa and BBs.
Conclusions: The reference diuretic group had less severe cardiovascular disease than other groups. Treatment with a CCB, BB or methyldopa was associated with an excess mortality in comparison with this reference group. The excess was similar in the different drug groups.