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Antihypertensives prevent headaches
11 October 2005
Antihypertensive drugs prevent headaches, a meta-analysis of trials indicates.
The across-the-board effect in four classes of the drugs suggests that this may be due to a reduction in blood pressure (BP), say the researchers, although, they note that observational studies did not point to high BP as a cause of headaches.
The analysis included data on 94 placebo-controlled randomized trials involving 17,641 people who received fixed doses of thiazide diuretics, beta blockers, ACE inhibitors, and angiotensin II receptor antagonists and 6603 who received placebo.
Antihypertensive treatment lowered BP by an average of 9.4 mmHg systolic and 5.5 mmHg diastolic, and people receiving therapy were a third less likely to report headaches than those using placebo (8.0% vs 12.4%, odds ratio [OR]=0.67, p<0.001).
This equated to about one in 30 treated people benefiting from having headaches prevented. Prevalence of headaches was reduced with all four classes of drugs (p<0.001 in each case).
The researchers, led by Malcolm Law (University of London, UK), then examined whether high blood pressure caused headaches in 16 observational studies, but found that just four reports supported this link.
Re-analyzing the placebo groups in the trials, they report: "On average, headaches were 17% less prevalent (95% CI: – 31% to 1%) for a 5-mm Hg lower diastolic BP, but the association did not formally reach statistical significance (p=0.06), and there was no association with systolic BP."
The team therefore writes: "The conclusion that the four classes of blood pressure–lowering drugs reduce the prevalence of headache by about a third (whatever the mechanism) is firm, but the issue of whether higher BP per se causes headache remains unresolved.
"This uncertainty, however, does not detract from the practical benefit that the increasing use of these drugs to prevent cardiovascular disease will prevent headache in several millions of people worldwide."
