Clinical efficacies of antihypertensive drugs

According to published data, the ability to prevent various
hypertension related events differs between the various
anti-hypertensive drug groups. Although absolute drug effects differ
among studies, relative drug effects could be considered constant. We
therefore explored the possibility of drawing statistically valid
conclusions about the differences in clinical efficacy between various
drug groups by doing an overview of published data. We made a
meta-analysis with a Bayesian fixed effect model in which we related
the drug effects to the effects of placebo drugs. We selected 27
clinical trials from the literature according to specific criteria,
including results both from studies reporting the effects of the newer
drugs when tested against diuretics and beta-blockers, and from studies
in which diuretics and beta-blockers had been tested against placebo.
We calculated the posterior probability distributions of the relative
effects of ACE-inhibitors versus calcium antagonists with three
different endpoints: stroke, coronary disease and heart failure with
point estimates of effects and with 95% credibility intervals. As an
intermediate step in this procedure we obtained similar information
about the effects of the three groups of active drugs, ACE-inhibitors,
calcium antagonists and diuretics or beta-blockers, tested against
placebo. For coronory disease we also tested calcium antagonists
against diuretics or beta-blockers. ACE-inhibitors and calcium
antagonists have an almost identical ability to prevent stroke in
hypertensive individuals with a risk ratio (RR) of 1.04. On the other
hand, calcium antagonists reduce coronary disease by only 8% relative
to placebo. When ACE-inhibitors and calcium antagonists are compared by
the Bayesian method, the outcome is a 14% difference in favour of the
ACE-inhibitors to prevent coronary disease, with a credibility interval
almost reaching identity. Nor do calcium antagonists do as well as
diuretics or beta-blockers in this respect, RR = 1.12 with 95%
credibility interval 1.01 to 1.24. All the tested drug groups have a
profound preventive effect on the occurrence of heart failure when
given to hypertensive patients, showing reductions of 42% to 54%. When
ACE-inhibitors are compared with calcium antagonists the risk ratio is
0.79, with a credibility interval 0.65 to 0.95. There is statistically
an indisputable difference between ACE-inhibitors and calcium
antagonists in respect of effects on coronary disease and heart failure
when treating hypertensive individuals, ACE-inhibitors being more
efficacious. There are no differences in the effect on stroke.
Moreover, beta-blockers or diuretics are also superior to calcium
antagonists in preventing coronary events.