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Antihypertensive efficacy in black patients

Systematic review
Results
Comment

Diversity is a wonderful thing, but awfully complicating when it comes to illness and therapy. So often terrific studies are performed, only to leave unanswered questions of whether results may differ by sex, or age, or race, or genomic makeup, let alone dose or intensity of the intervention, its duration, the severity of illness, or duration of disease. It is all very well hearing about yet another new gene being discovered that 'may' help determine treatments sometime in the future, but that is pie in the sky tomorrow, and treating patients now is the name of the game, whatever their differences. We have some help with antihypertensive therapy in black patients, thanks to a detailed and enthusiastic systematic review [1].

Systematic review

This set out to identify all trials that looked at antihypertensive drugs in hypertensive black adults, using a series of electronic databases, including the Cochrane Library. There was no language restriction, and there were, in addition, considerable attempts to locate data by other means, including contacting authors for unpublished details.

Any randomised trial lasting at least two weeks was eligible if it had a placebo control and provided information on arterial blood pressure.

Results

Twenty-six trials were eligible, conducted in the USA, Caribbean, or Africa. Most trials (22) had quality scores that made bias unlikely. Most trials included patients with diastolic blood pressure in the range of 90-115 mmHg. The median duration of treatment was eight weeks.

Table 1 shows the main results, and with the exception of beta-blockers for systolic blood pressure, all lowered blood pressure significantly more than placebo. The greatest blood pressure reduction, and largest proportion of patients achieving a diastolic blood pressure reduction goal, was with diuretics or calcium channel blockers. There was some suggestion that some beta-blockers might increase systolic blood pressure. Overall only 23% of people in these trials achieved adequate diastolic blood pressure reduction.



Table 1: Evidence for efficacy of antihypertensive drugs in hypertensive black patients



Number of
Mean BP reduction
(mmHg more than placebo)
Drug class
Trials
Patients
Systolic
Diastolic
DBP goal reached
(%)
Diuretics
10
581
11.8
8.1
31
Calcium channel blockers
6
421
11.6
7.8
46
a-blockers
3
262
7.4
3.4
13
ACE inhibitors
7
451
7.0
3.8
10
Angiotensin II blockers
4
933
3.6
3.4
19
b-blockers
8
482
3.5
5.4
19
Statistically significant differences in bold, shaded cells; Number of trials and patients for the largest comparison (SBP or DBP)
Diastolic blood pressure (DBP) goal was 90 mmHg or less, or reduced by 10 mmHg or more, or 10% decrease


Though an attempt was made to analyse the results according to different levels of initial blood pressure, limitations in the number of trials and patients, as well as different drugs and doses, made this something of a forlorn hope.

Adverse events were not analysed in detail, but headache, polyuria and nocturia, dizziness, tinnitus, bronchospasm, tachycardia, and cough were mentioned in some studies.

The review also sought mortality or morbidity outcomes in trials, and was able to calculate them for black patients in four trials. These trials all differed in patient characteristics, interventions, and endpoints. Some showed differences between black patients and white patients, and sometimes between black men and black women. Detailed reading of the review is needed to make the best sense of this for treating hypertensive black patients.

Comment

The good news is that the most commonly used antihypertensive drugs were effective in reducing blood pressure in hypertensive black people. It is probably essential reading for those writing guidelines. While there are always limitations in translating trials of antihypertensive monotherapy into clinical practice where, perhaps, multiple therapy is common, the addition of this evidence to clinical experience will be helpful, and add confidence to decisions made.

Reference:

  1. 1 LM Brewster et al. Systematic review: antihypertensive drug therapy in black patients. Annals of Internal Medicine 2004 141: 614-627.

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