patients had to be diagnosed with hypertension, according to the trial-specific definition, and randomized to treatment
with an RAAS inhibitor or control treatment. The cohort included 158998 patients (71401 RAAS inhibitor; 87597
control). The incidence of all-cause death was 20.9 and 23.3 per 1000 patient-years in patients randomized to RAAS in-
0.95, 95% CI: 0.91–1.00, P ¼ 0.032), and a 7% reduction in cardiovascular mortality (HR: 0.93, 95% CI: 0.88–0.99,
P ¼ 0.018). The observed treatment effect resulted entirely from the class of ACE inhibitors, which were associated
with a significant 10% reduction in all-cause mortality (HR: 0.90, 95% CI: 0.84–0.97, P ¼ 0.004), whereas no mortality re-
ductioncouldbedemonstratedwithARBtreatment(HR:0.99,95%CI:0.94–1.04,P ¼ 0.683).Thisdifferenceintreatment
In patients with hypertension, treatment with an ACE inhibitor results in a significant further reduction in all-cause
mortality. Because of the high prevalence of hypertension, the widespread use of ACE inhibitors may result in an
important gain in lives saved.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Hypertension † ACE inhibitor † ARB † Meta-analysis † Mortality
Angiotensin-converting enzyme inhibitors reduce
mortality in hypertension: a meta-analysis
of randomized clinical trials of
renin–angiotensin–aldosterone system inhibitors
involving 158998 patients
Laura C. van Vark1*, Michel Bertrand2, K. Martijn Akkerhuis1, Jasper J. Brugts1,
Kim Fox3, Jean-Jacques Mourad4, and Eric Boersma1
1Department of Cardiology, Thoraxcenter, Erasmus MC, ‘s Gravendijkwal 230, 3015 GE Rotterdam, The Netherlands;2Lille Heart Institute, Lille, France;3Royal Brompton and
National Heart Hospital, London, UK; and4Avicenne University Hospital, Bobigny and Paris 13 University, Paris, France
Received 24 August 2011; revised 15 February 2012; accepted 5 March 2012; online publish-ahead-of-print 17 April 2012
See page 1996 for the editorial comment on this article (doi:10.1093/eurheartj/ehs108)
Renin–angiotensin–aldosterone system (RAAS) inhibitors are well established for the reduction in cardiovascular
morbidity, but their impact on all-cause mortality in hypertensive patients is uncertain. Our objective was to
analyse the effects of RAAS inhibitors as a class of drugs, as well as of angiotensin-converting enzyme (ACE) inhibitors
and AT1 receptor blockers (ARBs) separately, on all-cause mortality.
We performed a pooled analysis of 20 cardiovascular morbidity–mortality trials. In each trial at least two-thirds of the
The World Health Organization describes hypertension as the
number one risk factor for mortality, as worldwide annually 7.5
million deaths (13% of all deaths) are attributable to high blood
pressure (BP)-related diseases, particularly cardiovascular diseases
(CVD).1For that reason, the guidelines of hypertension and cardi-
ology societies emphasize that hypertension treatment should aim
* Corresponding author. Tel: +31 107033004, Fax: +31 107044759, Email: firstname.lastname@example.org
Published on behalf of the European Society of Cardiology. All rights reserved. & The Author 2012.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which
permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
European Heart Journal (2012) 33, 2088–2097
at reducing the long-term risk of (cardiovascular) morbidity and
mortality.2,3Hypertension is often referred to as the ‘silent killer’,
as its presence is usually symptomless. Therefore, compliance to
antihypertensive medication is a challenge for most patients,
especially as adequate BP control often requires the use of multiple
agents, causing additional side effects and as a result inferior
adherence.2Thus, there is a continuing need for potent medica-
tions, preferably with beneficial effects on mortality, to improve
patients’ adherence to the treatment prescribed.
The benefits of antihypertensive treatment on cardiovascular
morbidity are thought to be mainly due to the BP-lowering
effect per se, independent of the class of drug employed, as has
been demonstrated with b-blockers, diuretics, calcium channel
blockers, and recently with the renin–angiotensin–aldosterone
system (RAAS) inhibitors.2Blockade of the RAAS is one of the
key therapeutic targets in patients with hypertension, as an over-
active RAAS is strongly associated with high BP. The RAAS con-
trols circulating volume and electrolyte balance in the human
body and is therefore an important regulator of haemodynamic
stability.4RAAS inhibitors are the most widely prescribed class
of drugs for the management of hypertension. Currently, the
most clinically relevant pharmacological agents that block the
RAAS are angiotensin-converting enzyme (ACE) inhibitors and
AT1 receptor blockers (ARBs). Both drugs block angiotensin II,
but ACE inhibitors are characterized by a decrease in the degrad-
ation of bradykinin leading to a release of nitric oxide and prosta-
glandins resulting in additional vasodilatation. These differences in
modes of action between ACE inhibitors and ARBs might have
clinical implications for patients with hypertension.5
Reductions in both cardiovascular morbidity and mortality have
been well demonstrated with RAAS inhibitors across specific popu-
lations that were selected and included for a criterion other than
hypertension per se. For example, SOLVD (enalapril in heart
failure), HOPE (ramipril in patients with high CVD risk), and
nificant reductions in the composite endpoint of death from cardio-
vascularcauses,myocardial infarctionor strokewithACEinhibitors.
In these trials, less than half of the patients enrolled had prevalent
hypertension.6–8The beneficial effects of RAAS inhibitors on (all-
of hypertension. Furthermore, most (antihypertensive) trials in
which the clinical effects of RAAS inhibitors were evaluated were
underpowered for this endpoint.9–11To evaluate the impact of
RAAS inhibitors on all-cause and cardiovascular mortality for their
main indication, hypertension, we undertook a meta-analysis of all
prospective randomized clinical trials that compared RAAS inhibi-
tors withcontrol therapy in different populations inwhich the abso-
lute majority of the patients had hypertension, and where the
expected benefits would mainly come from a decrease in BP.
We hypothesized that, taken all evidence together, RAAS inhibi-
tors would produce a significant mortality reduction compared
with (contemporary) control therapy. Although the primary aim
of this meta-analysis decided a priori was to evaluate RAAS inhibi-
tors as a class of drugs, we realized that ACE inhibitors and ARBs
have partly different modes of action. Therefore, we decided to
also study these two classes of drugs separately.
We argued that, if a significant effect on both all-cause and
cardiovascular mortality could be demonstrated, then treating
physicians would have an additional argument to motivate hyper-
tensive patients to comply with long-term treatment with these
We intended to include all publicly available morbidity–mortality pro-
spective randomized controlled trials that compared active treatment
with an ACE inhibitor or an ARB with control treatment (placebo,
active control, or usual care).
Trials were identified by a systematic search of OVID MEDLINE and
(ADIS) ISI Web of Science using a broad range of key words, including
‘antihypertensive agents’, ‘angiotensin-converting enzyme inhibitors’,
‘angiotensin II Type 1 receptor blockers’, ‘hypertension’, and ‘mortal-
ity’, published in English between 1 January 2000 and 1 March 2011.
We decided to start our search in the year 2000, because of our inten-
tion to evaluate the effect of RAAS inhibition on top of contemporary
treatment and considered the HOPE trial to be a landmark study in
this respect (published in the year 2000).7References of identified
papers and abstract listings of annual meetings of the American
Heart Association, the American College of Cardiology, European
Society of Cardiology, the American Society of Hypertension, the
European Society of Hypertension, and the Council for High Blood
Pressure Research were also examined during the same period. Each
trial identified in this search was critically and independently evaluated
by two investigators (L.v.V. and K.M.A.) for patient population, study
treatment, protocol, and endpoints.
A total of 512 publications met the above-mentioned search criteria
(Figure 1). We selected trials including different hypertensive popula-
tions for whom the benefits of RAAS inhibition would be expected
to be mainly due to BP reduction. We only included the principal
study publication, and excluded post hoc and subgroup analyses. Fur-
thermore, we excluded trials in which patients were selected
because of a specific disease, such as heart failure, acute coronary syn-
dromes, acute stroke, haemodialysis, atrial fibrillation, or post-cardiac
surgery patients, because of the expected benefits of RAAS inhibition
beyond BP lowering in these patient populations.12,13
Forty-four randomized controlled trials using RAAS blockade were
identified that corresponded with the inclusion criteria. We addition-
ally excluded eight trials in which less than two-thirds (66.7%) of the
studied population were diagnosed with hypertension, according to
the trial-specific definition. Ten trials were excluded due to either a
low number of participants (n , 100) or a low incidence of all-cause
death (n , 10), the primary endpoint of this study. Moreover, one
trial was excluded because all-cause mortality was not reported.
Finally, five trials (including INVEST, ACCOMPLISH, and ONTARGET)
were excluded because RAAS inhibitors were used simultaneously in
both trial arms.14–16Thus, a total of 20 trials were included in our ana-
lysis (Figure 1), which had a follow-up duration of at least 1 year.
This analysis is based on data that were obtained from the papers
reporting trials’ main results. Two authors (L.v.V., K.M.A.) independ-
ently extracted data from these reports, and resolved differences by
consensus. For each treatment arm, we recorded the number of
trial participants, the number of patients who reached the endpoint
of all-cause and cardiovascular mortality, the mean age at baseline,
ACE inhibitors reduce mortality in hypertension
the mean diastolic blood pressure and systolic blood pressure (SBP) at
baseline, the percentage of male participants, the percentage of
patients with diabetes mellitus, renal insufficiency, and hypertension,
as well as the total follow-up time (until death) in years.
The endpoints of this pooled analysis were all-cause and cardiovascular
mortality during long-term follow-up. Data on all-cause death were
available for all trials. Data on cardiovascular death were not available
for RENAAL, IDNT, MOSES, and CASE-J.
We aimed to provide estimates of the incidence of these endpoints
in patients randomized to RAAS inhibitors and control therapy, as well
as estimates of the absolute and relative reduction in the incidence of
the endpoints by RAAS inhibitors. Since the duration of follow-up
varied between the trials, we decided to base our analyses on the mor-
tality incidence rate (IR), which was assumed to be constant over time
in each of the comparison groups. The IR is defined as the number of
patients who reached the endpoint in the comparison group divided by
the patient-years of follow-up in the corresponding group (i.e. the sum
of the follow-up times for each individual). The latter figure is equal to
the number of patients multiplied by their mean follow-up duration.
To obtain the trial- and treatment-arm specific mean follow-up dur-
ation, the following five-step approach was applied. Firstly, we
observed whether the mean follow-up time per treatment arm was
Figure 1 Flow diagram of trial search and selection process. RAAS, renin–angiotensin–aldosterone system; RCT, randomized clinical trials.
L.C. van Vark et al.
stated in the paper. If this was not available, we then derived it from
the reported death rate by dividing the total number of deaths by
the annual death rate. If these data were not available, then the
mean follow-up time was estimated from incidences that were
derived from Kaplan–Meier curves, in combination with the number
of patients that were reported to be at risk at several follow-up
points. Finally, if we were not able to compute the mean follow-up
duration for each treatment arm separately, we used the mean follow-
up time that was reported for all trial participants together.
For each individual trial, the treatment-arm specific all-cause and car-
diovascular mortality IR was determined. We evaluated the assump-
tion that the mortality rate is constant over time by visually
inspecting the Kaplan–Meier curves of the studies in this meta-analysis,
comparing different time windows within each Kaplan–Meier curve.
We did not find any major deviation from this assumption. Further-
more, we realized that the follow-up time within each of the trials is
relatively short (the overall mean follow-up duration is 4.3 years).
Thus, on average, during the course of the trial, patients became
only 4 years older. In view of this fact, it seems reasonable to
assume that the IRs were constant over time.
Information on follow-up times is needed to obtain estimates of ab-
solute risks (and absolute treatment effects). However, because of the
assumptions that we used, our IR estimates might be somewhat in-
accurate. Therefore, we based our estimates of relative treatment
effects on the hazard ratios (HRs) and confidence intervals (CIs) or
standard errors that were reported for each trial. Actually, HRs
were available for all trials, except for RENAAL, SCOPE, and pilot
HYVET. For these trials, we calculated HRs based on the IRs in the
separate treatment arms.
Because of the large variety in active (and control) treatments, we
used a random-effects model to compute an overall pooled HR,
even in case statistical tests for heterogeneity across trials were non-
significant. Statistical heterogeneity was tested by Cochran’s Q statis-
tic,17and a P-value ,0.10 (two sided) was considered to indicate het-
erogeneity among trials. The degree of heterogeneity was presented as
an I2value. Publication bias was assessed by visually examining funnel
plot asymmetry and quantified by using an Egger regression test to cal-
culate two-tailed P-values.18
We hypothesized that the mortality reduction by antihypertensive
drugs might be influenced by age, gender, baseline SBP, BP reduction
during follow-up, and follow-up time. To evaluate this hypothesis,
we conducted linear regression analyses, based on trial-level data
(so-called ‘meta-regression’). The trial-specific mean age, percentage
of men, mean SBP, mean difference in BP reduction after 1 year of
follow-up between RAAS inhibitors and control therapy, and mean
follow-up time were considered as explanatory variables of the
natural logarithm of the trial-specific hazard ratio (lnHR) for all-cause
mortality. In this analysis, trial-level observations were weighed accord-
ing to the inverse of the squared standard error of lnHR, thus taking
into account the amount of ‘statistical information’ that is produced
by each trial. Secondly, by including follow-up time in this analysis
we were able to assess whether the mortality incidence ratio is con-
stant over time.
Although we hypothesized that, taken all evidence together, RAAS
inhibitors as a class of drugs would produce a homogenous treatment
effect in terms of a mortality reduction compared with (contempor-
ary) control therapy, we also performed stratified analyses according
to the class of drug (ACE inhibitor vs. ARBs), as we realized that
ACE inhibitors and ARBs have partly different modes of action. We
also performed stratified analyses according to type of control
(placebo vs. active treatment), and percentage of patients with dia-
betes mellitus or renal insufficiency at baseline (.50% vs. ,50%).
Pooled HRs for all-cause mortality were determined using a random
effects model for each stratum, and differences between strata were
All statistical tests were two-sided, and a P-value ,0.05 was consid-
ered significant. We used SAS 9.2 for Windows for data analysis.
A total of 20 trials fulfilled all selection criteria for this
meta-analysis, and their main characteristics are presented in
Table 1.9–11,19–35In total 158 998 patients were randomized to
RAAS inhibitor therapy (n ¼ 71401; 299 982 patient-years of
follow-up) or control treatment (n ¼ 87597; 377 023 patient-
years of follow-up). ACE inhibitors were used as the active treat-
ment in seven trials (n ¼ 76615); two of these studies were
placebo controlled.23,24,26,30,31,33,34Thirteen trials, of which five
were placebo-controlled, allocated participants to an ARB as the
active treatment (n ¼ 82383).9–11,19–22,25,27–29,32,35
On average, 91% of the trial participants were hypertensive
according to the definition used in each trial. The mean baseline
SBP was 153 mmHg (range of the means across trials 135–182),
the mean age was 67 years (range of the means across trials
59–84) and 58% of participants were man (range of this percent-
age across trials 36–80; Table 1).
During a mean follow-up of 4.3 years, 6284 of the patients assigned
to an RAAS inhibitor reached the endpoint of all-cause death. This
corresponds with an IR of 20.9 deaths per 1000 patient-years.
During the same period, a total of 8777 patients assigned to
control therapy had all-cause death, implying an IR of 23.3
deaths per 1000 patient-years. RAAS inhibition was associated
with a statistically significant reduction in all-cause mortality in
three individual trials, ASCOT-BPLA, ADVANCE, and HYVET
In all 20 trials grouped together, treatment with an RAAS inhib-
ition was associated with a statistically significant 5% reduction in
all-cause mortality (HR: 0.95, 95% CI: 0.91–1.00, P ¼ 0.032;
Figure 2). The degree of heterogeneity in the treatment effect
across all trials was low (I2: 15%) and non-significant (P ¼ 0.266).
No funnel-plot asymmetry was visualized, and the P-value using
an Egger regression test for all-cause mortality was .0.10 (inter-
cept 20.3, 95% CI: 21.3–0.68; P ¼ 0.53), indicating no evidence
for publication bias.
Excluding the four trials that did not report on cardiovascular mor-
tality, 2570 patients assigned to RAAS inhibition had cardiovascular
death. Based on a total of 295 617 patient-years of follow-up, the
IR was 8.7 per 1000 patient-years. The IR in patients assigned to
control therapy was 10.1 per 1000 patient-years (3773 events;
ACE inhibitors reduce mortality in hypertension
2001 1513 LosartanPlacebo
20011715 Irbesartan Amlodipine or placebo
2002 9193Losartan with and without
200233357 Lisinopril Chlorthalidone or amlodipine
20036083 ACE inhibitor (enalapril) Diuretic (HCTZ)
2003 4937Candesartan Placebo
20031283 Lisinopril Diuretic or no treatment
2004 1650 ACE inhibitorNifedipine
200415245 Valsartan Amlodipine
2005 1352Eprosartan Nitrendipine
2005 19257Amlodipine with and without
2007 3081Valsartan Non-ARB
2007 11140Perindopril with indapamidePlacebo
2008 3845Indapamide with and without
200820332 Telmisartan Placebo
Baseline characteristics of study population in 20 trials (n 5 158 998
Active drug ControlMean
Men, %IR in
19.5 Atenolol with and without HCTZ
15.5Atenolol with and without
HCTZ, hydrochlorothiazide; ACE, angiotensin-converting enzyme; ARB, angiotensin-receptor blocker; SBP, systolic blood pressure; IR, incidence rate per 1000 patient-years.
L.C. van Vark et al.
372105 patient-years of follow-up), resulting in a significant 7%
overall reduction in cardiovascular mortality (HR: 0.93, 95% CI:
0.88–0.99, P ¼ 0.018; Figure 2). The degree of heterogeneity in
treatment effect across all trials was low (I2: 23%) and non-
significant (P ¼ 0.194). There was no evidence of publication bias.
inhibitors vs. AT1 receptor blockers
All seven trials together, ACE inhibitors were associated with a
statistically significant 10% reduction in all-cause mortality (IR:
20.4 vs. 24.2 deaths per 1000 patient-years; HR: 0.90, 95% CI:
0.84–0.97, P ¼ 0.004). No significant mortality reduction could
be demonstrated with ARB treatment (13 trials; IR: 21.4 vs. 22.0
deaths per 1000 patient-years; HR: 0.99, 95% CI: 0.94–1.04,
P ¼ 0.683). This difference in the treatment effect between ACE
inhibitors and ARBs was statistically significant (P-value for inter-
action 0.036). Apparently, the observed mortality reduction in
the overall group of RAAS inhibitors was completely driven by
the beneficial effect of the ACE inhibitors.
As far as the ACE inhibitor trials are concerned, the largest mor-
tality reductions were observed in ASCOT-BPLA, ADVANCE, and
HYVET, all of which studied the ACE inhibitor perindopril (pooled
HR: 0.87, 95% CI: 0.81–0.93, P-value ,0.001). However, there
was no evidence of heterogeneity among the ACE inhibitor trials
in the effect of the studied ACE inhibitor regimen on all-cause
mortality (P-value for heterogeneity 0.310, I2: 16%; Figure 3).
There was also no evidence of heterogeneity in the effect of
ARBs (P-value for heterogeneity 0.631, I2: 0%).
Patients randomized to an ACE inhibitor had 9.1 cardiovascular
deaths per 1000 patient-years, compared with 11.2 in their con-
trols (HR: 0.88; 95% CI: 0.77–1.00; P ¼ 0.051). In the ARB trials,
the IRs were 8.8 and 9.2 cardiovascular deaths per 1000 patient-
years for patients assigned to ARB and control therapy, respective-
ly (HR: 0.96; 95% CI: 0.90–1.01; P ¼ 0.143). The test for hetero-
geneity in effects on cardiovascular mortality between ACE
inhibitors and ARBs was statistically non-significant (P ¼ 0.227).
Multiple linear regression analysis showed a significant (P ¼ 0.035)
association between the trial-specific mean SBP (measured at base-
line), and the relative mortality reduction by RAAS blockade. The
mortality reduction was largest in trials with the highest mean
Figure 2 All-cause and cardiovascular mortality treatment effect of renin–angiotensin–aldosterone system blockade in all included trials. HR,
hazard ratio; CI, confidence interval; RAAS, renin–angiotensin–aldosterone system. Overall P ¼ 0.032 for all-cause mortality. Overall P ¼ 0.018
for cardiovascular mortality.
ACE inhibitors reduce mortality in hypertension
baseline BP values. Secondly, there was a significant (P ¼ 0.008) re-
lation between the trial specific mean difference in BP between the
studied RAAS inhibitor and control therapy at 1-year follow-up,
and the mortality reduction produced by the RAAS inhibitor.
The mortality reduction was largest in trials with the largest differ-
ence in mean SBP reduction. No significant association was found
between the trial-specific mean age, man/woman ratio, mean
follow-up time and the mortality reduction by RAAS blockade.
Mean follow-up time was also not related to the observed mortal-
ity reduction, supporting our hypothesis that the mortality inci-
dence ratio is constant over time (at least for the mean duration
of 4.3 years).
Similar HRs for all-cause mortality were found in clinical trials that
compared RAAS inhibition with placebo (HR: 0.95, 95% CI:
0.88–1.02, P ¼ 0.177) and with active control (HR: 0.95, 95% CI:
0.91–1.01, P ¼ 0.066; P-value for interaction 0.889). Likewise, no
heterogeneity in treatment effect was observed with respect to
the percentage of participants with diabetes mellitus or renal
This meta-analysis, which included almost 160000 patients, sought
to evaluate the effect of RAAS inhibitors as a class of drugs on total
and cardiovascular mortality in their main indication hypertension.
Overall, the results show a 5% reduction in all-cause mortality
during a 4-year follow-up period associated with the class of
RAAS inhibitors. This mortality reduction was found when com-
pared with placebo, as well as in comparison with other
BP-lowering drugs. However, in a stratified analysis according to
the class of drug, it was shown that the observed overall all-cause
mortality reduction was almost completely a result of the benefi-
cial effect of the class of ACE inhibitors (10% relative reduction
in all-cause mortality), whereas the ARBs showed a neutral treat-
ment effect. The findings are firm, as the analysis included a large
number of patient-years (677005) and endpoints (15061
deaths). The findings are relevant to clinical practice, as they are
based on data from well-designed randomized trials encompassing
a broad population of patients with high BP, who were well-treated
for concomitant risk factors and who represent usual hypertensive
patients seen today.
Reduction in mortality is the primary goal of antihypertensive
therapy.2Paradoxically, the effect of RAAS inhibitors on mortality
Figure 3 The all-cause mortality treatment effect of ACE inhibitor and ARB trials. HR, hazard ratio; CI, confidence interval; ACE, angiotensin-
converting enzyme; ARB, angiotensin receptor blocker. P ¼ 0.004 for the treatment effect of ACE inhibitor on all-cause mortality. P ¼ 0.683
for the treatment effect of ARB on all-cause mortality.
L.C. van Vark et al.
in hypertensive patients remained uncertain and had never been
systematically evaluated. To our knowledge, no prior published
meta-analysis investigated the efficacy of RAAS inhibitors on all-
cause and cardiovascular mortality in their main indication of
hypertension. Previous analyses in for example heart failure or cor-
onary artery disease populations (with or without hypertension)
demonstrated a reduction in cardiovascular events, stroke, and
mortality.36,37In addition, a pooled analysis of trials in patients
with cardiovascular disease (including hypertension) concluded
that the reduction in cardiovascular mortality and stroke with
RAAS inhibitors is BP dependent.38In our analyses, the significant
reduction in cardiovascular mortality associated with RAAS inhib-
ition supports previous literature.
As stated, the primary aim of this meta-analysis decided a priori
was to test the hypothesis that RAAS inhibitors as a class of drugs
would have a beneficial effect on total mortality in hypertension,
when compared with contemporary control antihypertensive
therapy. However, as we realized that, among the RAAS inhibitors,
the ACE inhibitors and ARBs have different mechanisms of action,
we also decided to study whether there was a differential effect on
mortality between these two classes of drugs. Indeed, our analysis
clearly showed that nearly all of the mortality reduction was
observed with ACE inhibitors. Contrary, there was no clear
benefit from the ARBs. This was supported by the sensitivity ana-
lysis which showed a significant stronger treatment effect in the
ACE inhibitor trials compared with the ARB trials. With respect
to this finding several points deserve consideration.
The reduced effect of ARBs on mortality when compared with
ACE inhibitors has also previously been discussed.39,40A recent
meta-analysis of 37 ARB trials also failed to detect a reduction in
all-cause or cardiovascular mortality in a broad population of
patients.41The differences in the modes of action between ACE
inhibitors and ARBs, and the small-but-definite BP-independent re-
duction in CAD mortality with ACE inhibitors, which has not been
observed with ARBs or other antihypertensive agents, might con-
tribute to this finding.42On the other hand, others have demon-
strated that BP-dependent beneficial effects in the prevention of
stroke and heart failure are similar for ACE inhibitors and ARBs.
ACE inhibitors and ARBs have also been shown to be equally ef-
fective in preventing atrial fibrillation and new-onset diabetes.43,44
Furthermore, it should be emphasized that we did not design this
meta-analysis to make a head-to-head comparison between ACE
inhibitors and ARBs. The finding that the beneficial effect is seen
in the ACE inhibitor population as opposed to the ARB population
should be considered a post hoc observation. Given the nature of
meta-analyses, which are per definition data-driven, the differential
effect between ACE inhibitors and ARBs should be interpreted
with caution to avoid overstating this subgroup finding vis-a `-vis
the a priori hypothesis. In this respect it should also be noted
that the difference in effect on cardiovascular mortality between
ACE inhibitors and ARBs was not statistically significant. Further-
more, two previous studies were designed to compare ACE inhi-
bitors and ARBs in an hypertensive population, but both the
ONTARGET (telmisartan vs. ramipril) and DETAIL (telmisartan
vs. enalapril) trial did not show a differential treatment effect
between ARBs and ACE inhibitors.15,45Thus, at present, the
results of this analysis do not warrant changing clinical practice
treatment guidelines that recommend that an ARB may be used
in ACE inhibitor-intolerant hypertensive patients.2Hopefully, our
findings will form the basis of further analysis and studies into
the effects of BP treatment and total mortality which is the first
line priority in the guidelines for the management of hypertension.
It might be argued that the observed 5% relative mortality re-
duction in the overall group of RAAS inhibitors, and the 10% rela-
tive mortality reduction in the ACE inhibitor group is small, and
only found to be statistically significant in our analysis because of
statistical ‘overpowering’. Indeed, in meta-analyses clinically irrele-
vant treatment effects might become statistically significant (i.e. the
estimated effect divided by the standard error is .1.96) simply
because of the large size of the aggregate (or pooled) trials. In
our view, however, the observed mortality reduction in this
meta-analysis is clinically relevant indeed, for several reasons.
Firstly, it should be realized that the treatment effect was
reached in patients who did receive a broad range of other con-
temporary risk-reduction therapies, including statins, antiplatelet
therapy, beta-blockers, diuretics, and other BP-lowering medica-
tion (note that, as per design, we included trials that were con-
ducted during 2000–2011). Secondly, the estimated absolute
mortality reduction was 2.4 per 1000 patient-years for the RAAS
inhibitors as a group and 3.8 per 1000 patient-years for the class
of ACE inhibitors. This is an interesting figure, particularly since
the prevalence of hypertension in Western (CAD) populations is
high,46despite the widespread use of BP-lowering medication.
Thus a wider application of these agents, in particular of ACE inhi-
bitors, may have substantial effects on the population level. Inter-
estingly, the observed mortality reduction was largest in trials
with the highest baseline SBP. The observed mortality reduction
may be used as an additional argument to stimulate patients to
adhere to the prescribed treatment.
Several limitations of our analysis have to be mentioned. Firstly,
there was a great deal of variation between the studied popula-
tions. For example, trials used different definitions of hypertension,
different dosages of the active and control drug, different target BP
levels, different follow-up times, and in several studies patients had
other concomitant conditions and background therapy. Although
this does not hamper the generalizability of our results, it makes
it challenging to accurately estimate the effect of RAAS inhibition
in a broad range of routine clinical practice situations.
Secondly, this meta-analysis is based on trial level data, rather
than on individual patient data. Information on background
therapy and co-morbidities were not available in several trial
reports. Thus, we could not reliably analyse the relation between
these factors and the observed mortality reduction. Moreover,
the treatment arm-specific follow-up time was not available in all
trials, we therefore derived follow-up time from either the
reported death rate, Kaplan–Meier curves, or mean follow-up dur-
ation. This is an approximation of the true follow-up time, and we
appreciate that our estimates of mortality incidence might be
somewhat over or underestimated. However, importantly, this
methodology had not influenced the estimation of the observed
relative mortality reduction, which was mainly based on the HRs
that were reported for the separate trials.
ACE inhibitors reduce mortality in hypertension
Finally, this meta-analysis assumed a class effect among the dif-
ferent ACE inhibitors and ARBs. The validity of this concept was
not challenged by formal statistical tests on heterogeneity of treat-
ment effects among the different (ACE inhibitor and ARB) trials.
Still, it should be realized that differences may exist between
drugs within the same class that are simply missed due to lack of
statistical power. It should therefore be emphasized that our find-
ings should be interpreted in relation to the pharmacological prop-
erties of the applied agents.
This meta-analysis, which involved almost 160 000 patients,
demonstrated that RAAS inhibitors as a class of antihypertensive
drugs were associated with a significant 5% relative reduction in all-
cause mortality in populations with a high prevalence of hyperten-
sion when compared with contemporary control antihypertensive
therapy. Stratified subgroup analysis according to class of drug
showed a differential treatment effect between ACE inhibitors
and ARBs. The overall reduction in all-cause mortality resulted
almost completely from the class of ACE inhibitors, which were
associated with a statistically significant 10% relative reduction in
all-cause mortality, whereas no mortality reduction was observed
with the ARBs. In view of the high prevalence of hypertension in
the general population, widespread use of ACE inhibitors may
therefore result in a considerable gain in lives saved. The results
of this study provide a convincing argument to improve treatment
adherence in the millions of people around the world suffering
from hypertension and its sequelae.
Funding to pay the Open Access publication charges for this article was
provided by the Department of Cardiology, Thoraxcenter, Erasmus
Conflict of interest: M.B reports to have previously received re-
search grants, fees, and honoraria from: Merck-Sharpe Dohme, Ameri-
can Medicine Company, Lilly, Servier, and Sanofi-Aventis. K.F. receives
fees, and research grants from Servier Laboratories. During the previ-
ous 5 years, J.J.M. has received fees for an occasional consultancy or
guest speaker meeting from various pharmaceutical companies.
L.C.v.V., K.M.A., J.J.B., and E.B. have no conflict of interest to report.
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ACE inhibitors reduce mortality in hypertension