Background: Headache is usually associated with high blood pressure (BP) despite the lack of evidence of such an association in most observational studies. Ambulatory BP monitoring provides an opportunity to analyze this relation because it permits measurement of BP before, during, and after episodes of headache.
Methods: We evaluated 76 patients with mild hypertension who underwent clinical evaluation, ambulatory BP monitoring, and questioning about the occurrence of headache and its characteristics during monitoring. The 24-hour BP curves of patients with and without headache during monitoring were compared using analysis of variance for multiple factors and repeated measurements. Hourly averages of BP surrounding the episode and 24-hour mean BP of patients with headache were compared using paired sample t tests.
Results: Twenty-five participants (33%) experienced headache during monitoring. Their 24-hour BP curves did not differ from those of participants without headache. Mean 24-hour BP was not different from BP registered during the episode of headache (mean +/- SD systolic BP: 137.0 +/- 17.3 vs 139.4 +/- 21.1; P =.13; diastolic BP: 83.3 +/- 12.8 vs 85.0 +/- 18.2; P =.30). Blood pressure values registered during the episode of headache and in the hours before and after the episode were not different from each other. Analysis restricted to 8 patients with migrainelike headache showed a similar pattern.
Conclusions: In patients with mild hypertension, there is no association between the occurrence of headache and variation of BP. Health professionals must discourage patients with hypertension from believing that they can rely on the presence of such a symptom to know about their BP levels.