This is the first update of a review published in 2009. Sustained moderate to severe
elevations in resting blood pressure leads to a critically important clinical question:
What class of drug to use first‐line? This review attempted to answer that question.
To quantify the mortality and morbidity effects from different first‐line antihypertensive
drug classes: thiazides (low‐dose and high‐dose), beta‐blockers, calcium channel blockers,
ACE inhibitors, angiotensin II receptor blockers (ARB), and alpha‐blockers, compared
to placebo or no treatment. Secondary objectives: when different antihypertensive
drug classes are used as the first‐line drug, to quantify the blood pressure lowering
effect and the rate of withdrawal due to adverse drug effects, compared to placebo
or no treatment. The Cochrane Hypertension Information Specialist searched the following
databases for randomized controlled trials up to November 2017: the Cochrane Hypertension
Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL),
MEDLINE (from 1946), Embase (from 1974), the World Health Organization International
Clinical Trials Registry Platform, and ClinicalTrials.gov. We contacted authors of
relevant papers regarding further published and unpublished work. Randomized trials
(RCT) of at least one year duration, comparing one of six major drug classes with
a placebo or no treatment, in adult patients with blood pressure over 140/90 mmHg
at baseline. The majority (over 70%) of the patients in the treatment group were taking
the drug class of interest after one year. We included trials with both hypertensive
and normotensive patients in this review if the majority (over 70%) of patients had
elevated blood pressure, or the trial separately reported outcome data on patients
with elevated blood pressure. The outcomes assessed were mortality, stroke, coronary
heart disease (CHD), total cardiovascular events (CVS), decrease in systolic and diastolic
blood pressure, and withdrawals due to adverse drug effects. We used a fixed‐effect
model to to combine dichotomous outcomes across trials and calculate risk ratio (RR)
with 95% confidence interval (CI). We presented blood pressure data as mean difference
(MD) with 99% CI. The 2017 updated search failed to identify any new trials. The original
review identified 24 trials with 28 active treatment arms, including 58,040 patients.
We found no RCTs for ARBs or alpha‐blockers. These results are mostly applicable to
adult patients with moderate to severe primary hypertension. The mean age of participants
was 56 years, and mean duration of follow‐up was three to five years. High‐quality
evidence showed that first‐line low‐dose thiazides reduced mortality (11.0% with control
versus 9.8% with treatment; RR 0.89, 95% CI 0.82 to 0.97); total CVS (12.9% with control
versus 9.0% with treatment; RR 0.70, 95% CI 0.64 to 0.76), stroke (6.2% with control
versus 4.2% with treatment; RR 0.68, 95% CI 0.60 to 0.77), and coronary heart disease
(3.9% with control versus 2.8% with treatment; RR 0.72, 95% CI 0.61 to 0.84). Low‐
to moderate‐quality evidence showed that first‐line high‐dose thiazides reduced stroke
(1.9% with control versus 0.9% with treatment; RR 0.47, 95% CI 0.37 to 0.61) and total
CVS (5.1% with control versus 3.7% with treatment; RR 0.72, 95% CI 0.63 to 0.82),
but did not reduce mortality (3.1% with control versus 2.8% with treatment; RR 0.90,
95% CI 0.76 to 1.05), or coronary heart disease (2.7% with control versus 2.7% with
treatment; RR 1.01, 95% CI 0.85 to 1.20). Low‐ to moderate‐quality evidence showed
that first‐line beta‐blockers did not reduce mortality (6.2% with control versus 6.0%
with treatment; RR 0.96, 95% CI 0.86 to 1.07) or coronary heart disease (4.4% with
control versus 3.9% with treatment; RR 0.90, 95% CI 0.78 to 1.03), but reduced stroke
(3.4% with control versus 2.8% with treatment; RR 0.83, 95% CI 0.72 to 0.97) and total
CVS (7.6% with control versus 6.8% with treatment; RR 0.89, 95% CI 0.81 to 0.98).
Low‐ to moderate‐quality evidence showed that first‐line ACE inhibitors reduced mortality
(13.6% with control versus 11.3% with treatment; RR 0.83, 95% CI 0.72 to 0.95), stroke
(6.0% with control versus 3.9% with treatment; RR 0.65, 95% CI 0.52 to 0.82), coronary
heart disease (13.5% with control versus 11.0% with treatment; RR 0.81, 95% CI 0.70
to 0.94), and total CVS (20.1% with control versus 15.3% with treatment; RR 0.76,
95% CI 0.67 to 0.85). Low‐quality evidence showed that first‐line calcium channel
blockers reduced stroke (3.4% with control versus 1.9% with treatment; RR 0.58, 95%
CI 0.41 to 0.84) and total CVS (8.0% with control versus 5.7% with treatment; RR 0.71,
95% CI 0.57 to 0.87), but not coronary heart disease (3.1% with control versus 2.4%
with treatment; RR 0.77, 95% CI 0.55 to 1.09), or mortality (6.0% with control versus
5.1% with treatment; RR 0.86, 95% CI 0.68 to 1.09). There was low‐quality evidence
that withdrawals due to adverse effects were increased with first‐line low‐dose thiazides
(5.0% with control versus 11.3% with treatment; RR 2.38, 95% CI 2.06 to 2.75), high‐dose
thiazides (2.2% with control versus 9.8% with treatment; RR 4.48, 95% CI 3.83 to 5.24),
and beta‐blockers (3.1% with control versus 14.4% with treatment; RR 4.59, 95% CI
4.11 to 5.13). No data for these outcomes were available for first‐line ACE inhibitors
or calcium channel blockers. The blood pressure data were not used to assess the effect
of the different classes of drugs as the data were heterogeneous, and the number of
drugs used in the trials differed. First‐line low‐dose thiazides reduced all morbidity
and mortality outcomes in adult patients with moderate to severe primary hypertension.
First‐line ACE inhibitors and calcium channel blockers may be similarly effective,
but the evidence was of lower quality. First‐line high‐dose thiazides and first‐line
beta‐blockers were inferior to first‐line low‐dose thiazides. Thiazides best first
choice for hypertension Review Question(s) In this first update of a review published
in 2009, we wanted to determine which drug class was the best first‐line choice in
treating adult patients with raised blood pressure. We searched the available medical
literature to find all the trials that compared the drugs to placebo or no treatment
to assess this question. The data included in this review are up to date as of November
2017. Background High blood pressure or hypertension can increase the risk of heart
attacks and stroke. One of the most important decisions in treating people with elevated
blood pressure is what drug class to use first. This decision has important consequences
in terms of health outcomes and cost. Study characteristics We found no new trials
in this updated search. In the original review, we found 24 studies that randomly
assigned 58,040 adult people (mean age 62 years) with high blood pressure, to four
different drug classes or placebo . Duration of these studies ranged from three to
five years. Drug classes studied included thiazide diuretics, beta‐blockers, ACE inhibitors,
and calcium channel blockers. Key Results We concluded that most of the evidence demonstrated
that first‐line low‐dose thiazides reduced mortality, stroke, and heart attack. No
other drug class improved health outcomes better than low‐dose thiazides. Beta‐blockers
and high‐dose thiazides were inferior. Conclusions High‐quality evidence supported
that low‐dose thiazides should be used first for most patients with elevated blood
pressure. Fortunately, thiazides are also very inexpensive. Quality of evidence The
evidence for first‐line low dose thiazides was high quality. For the other classes,
we judged the evidence to be moderate or low quality.