Study selection and description
An initial search yielded 396 articles, subsequently narrowed to 4
articles for full text review (Supporting Information Table S1). These 4
articles comprised of randomised control trials comparing CCB to other
anti-hypertensives in women with HDP, and included Black women in their
demographics. An overview of the included studies’ characteristics and
primary outcomes is illustrated in Figure 1 included in online
supplementary material.
However, 3 out of 4 articles did not publish treatment effect by race,
and therefore could not be used to answer the review question. We
established contact with authors from all 3 studies where race based
outcomes were not published however they were unable to grant access to
original trial data, and therefore a meta-analysis was not possible.
Scardo et al randomised pregnant patients admitted to the Medical
University of South Carolina with hypertensive emergencies, defined as a
sustained systolic blood pressure of > 170 mm Hg or
diastolic blood pressure of >105 mm Hg, to receive either
oral Nifedipine (CCB) and 50 millilitres of Sodium Chloride or
intravenous Labetalol and oral placebo consisting of corn starch powder
in a double-blind trial. Black pregnant women comprised 62 percent of
the sample size.12 The primary outcome was the time
interval required to achieve the therapeutic blood pressure goal of
<160 mm Hg systolic and <100 mm Hg diastolic.
Patients receiving oral Nifedipine more rapidly achieved the therapeutic
blood pressure goal in 25.0+ 13.6 minutes (mean+ SD) as
compared with 43.6+ 25.4 minutes in those receiving Labetalol (p=
0.002). They also demonstrated that the Nifedipine group required
significantly fewer doses (1.5 + 0.5 vs 2.5 + 1.5; p< 0.001) to reach the target blood pressure.
Belfort et al conducted an unblinded, randomised, multicentre trial in
which 1650 patients with severe pre-eclampsia, defined as elevated blood
pressure (> 140/90 mm Hg) with
>1 + proteinuria and presence of one or more of the
following: symptoms of pre-eclampsia, deranged liver function tests,
intrauterine growth restriction or oligohydramnios; or persistent blood
pressure > 160/110 mm Hg with proteinuria in the
absence of other features, were included. Patients were allocated to
oral Nimodipine (CCB) or intravenous Magnesium
Sulphate.13 Blood pressure control was one of this
study’s secondary outcomes. Baseline blood pressures and overall blood
pressure readings were similar in both groups, although the authors
noted that the group that received Magnesium Sulphate required
Hydralazine more frequently to achieve target blood pressure levels. In
the first hour after drug administration, there was a higher reduction
of mean arterial pressure in the Nimodipine group compared to the
Magnesium Sulphate group (-8.2% vs -4.2%). Within three hours of drug
administration, reduction in mean arterial pressure was maintained in
the Nimodipine group at 8.3 percent whereas the Magnesium Sulphate group
had a 7.2 percent decrease in this time frame. Black patients accounted
for 42 percent of the study group.
Sharma et al conducted a prospective, unblinded, randomised control
trial amongst postpartum women with persistent hypertension, defined as
sustained systolic blood pressure > 150 mm Hg and
diastolic blood pressure > 100 mm
Hg.14 25 participants each were allocated to Labetalol
versus extended release Nifedipine. Time elapsed prior to achieving
blood pressure control was similar between both groups (36.6 hours with
Labetalol vs 38.2 hours with Nifedipine; p=0.51). In this study, where
36 percent of the group were Black, both oral Labetalol and Oral
extended release Nifedipine were effective for the treatment of
post-partum hypertension. At 72 hours post-partum, mean systolic blood
pressure recorded for the Labetalol group was 140 (+ 15) mm Hg
(mean+ SD) vs 141 (+ 27) mm Hg in Nifedipine group (p=0.94)
and mean diastolic blood pressures were measured at 89 (+ 4) mm Hg
vs 87 (+ 13) mm Hg (p=0.70) in Labetalol and Nifedipine groups
respectively. Although time to blood pressure control did not differ
significantly between medication groups, Labetalol achieved control more
often with the starting dose (76 percent with Labetalol vs 46 percent
with Nifedipine; p=0.04) and with fewer minor side effects compared to
Nifedipine (20 percent with Labetalol vs 48 percent with Nifedipine;
p=0.04).
The remaining article by Webster et al was a multi-centre randomised
control trial in the U.K., which compared the effectiveness of Labetalol
and Nifedipine in the management of chronic hypertension in
pregnancy.15This study comprised of 62 Black pregnant
patients who accounted for 54 percent of the study population of 112
women. A pre-specified exploratory subgroup analysis of the impact of
ethnicity on efficacy of each treatment did not show any significant
difference in mean systolic or diastolic brachial blood pressure in
Black women (systolic 0.5 mm Hg; −4 to 5 mm Hg; diastolic 0.1 mm Hg; −3
to 3 mm Hg). No difference in mean systolic blood pressure was seen
between treatment groups in study participants (−0.4 mm Hg; −4 to 3 mm
Hg), but a 4-mm Hg (−6.6 to −0.8 mm Hg; p=0.015) reduction in mean
diastolic blood pressure was seen in the Labetalol arm in non-Black
participants. The authors concluded that some variation in treatment
effect by ethnicity was noted, with Labetalol having a greater effect on
reducing diastolic blood pressure in non-Black women. Nifedipine was
associated with reduced central aortic pressure however the study was
not powered to calculate what the most effective anti-hypertensive
treatment for Black women with HDP is.