Elevated blood pressure and headache disorders in China – associations, under-treatment and implications for public health

BACKGROUND: Both hypertension (HTN) and headache disorders are highly prevalent worldwide. Our purpose, in a nationwide study of the Chinese general population, was to evaluate any association between primary headache disorders and elevated blood pressure (eBP). We could not collect data on antihypertensive therapy, but took the view that, whatever such therapy might be taken, eBP was a sign that it was failing to meet treatment needs. Therefore, as a secondary purpose, important from the public-health perspective, we would present the prevalence of eBP (treated or not) as indicative of unmet health-care need in China. METHODS: This was a questionnaire-based nationwide cross-sectional door-to-door survey using cluster random-sampling, selecting one adult (18–65 years) per household. Headache was diagnosed by ICHD-II criteria and eBP as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg. Chi-squared test and multivariate logistic regression analysis were used to assess the strength and significance of associations. We set significance at P ≤ 0.05. RESULTS: Of 5,041 survey participants (participation rate 94.1 %), 154 were excluded because of missing BP data, leaving 4,987 for analysis [mean age: 43.6 ± 12.8 years; male 2,532 (mean age: 43.4 ± 12.9 years); female 2,455 (mean age 43.9 ± 12.8 years)]. There were 466 participants with migraine, 535 with tension type headache (TTH) and 48 with all causes of headache on ≥15 days/month. The prevalence of eBP was 22.1 % (males 22.9 %, females 21.3 %). No associations of eBP with any of the headache disorders survived multivariate adjusted analysis. The demographic and anthropometric variables most strongly associated with eBP were higher age (AOR 3.7) and being overweight (AOR 2.4), seen in both genders. Less strong were male gender, lower educational level and urban habitation. CONCLUSIONS: We found no clear-cut associations between eBP and any headache disorder. The associations with demographic and anthropometric variables may have acted as confounders in past reports to the contrary. We did find an alarmingly high prevalence of eBP, recognizing that this signals substantial under-treatment in China of a serious condition, and therefore a major public-health concern.