European Journal of Neurology 2014
doi:10.1111/ene.12547
Blood pressure as a risk factor for headache and migraine: a prospective population-based study C. F. Fagernæsa, I. Heuchb, J.-A. Zwartb,c, B. S. Winsvoldb,c, M. Lindea,d and K. Hagena,d a
Department of Neuroscience, Norwegian University of Science and Technology, Trondheim; bDepartment of Neurology and FORMI, Oslo University Hospital, Oslo; cInstitute of Clinical Medicine, University of Oslo, Oslo; and dNorwegian National Headache Centre, St Olavs University Hospital, Trondheim, Norway
Keywords:
blood pressure, headache, hypertensionassociated hypalgesia, migraine Received 27 February 2014 Accepted 2 July 2014
Background and purpose: During the past decade, several population-based studies have found an inverse association between blood pressure (BP) and headache. However, most of them have a cross-sectional design or lack a validated definition of a headache-free population at baseline. Therefore, additional population-based studies using a clearly defined headache-free population and a prospective design are warranted. Methods: Data from two large epidemiological studies, the Nord-Trondelag Health Survey 1995–1997 (HUNT 2) and 2006–2008 (HUNT 3), were used to evaluate the association between BP (systolic, diastolic and pulse pressure) at baseline and headache (migraine and tension type headache) at follow-up. Results: An inverse relationship was found between all three BP measures at baseline in HUNT 2 and any headache in HUNT 3, more evident for systolic BP [odds ratio (OR) 0.90 per 10 mmHg increase in systolic BP, 95% confidence interval (CI) 0.87–0.93, P < 0.001] and pulse pressure (OR 0.84 per 10 mmHg increase in pulse pressure, 95% CI 0.80–0.89, P < 0.001) than for diastolic BP (OR 0.92 per 10 mmHg increase in diastolic BP, 95% CI 0.87–1.00, P = 0.036). The most robust finding, evident for both sexes, was that increased pulse pressure was linked to decreased prevalence of both migraine and tension type headache. Conclusion: An inverse relationship between BP and subsequent development of headache was confirmed in this large-scale population-based cohort study. Nevertheless, further research is needed to investigate the underlying mechanisms explaining these findings.
Introduction Headache is a major societal health problem and a cause of large monetary losses [1,2]. In order to understand the causes behind headache, investigations of protective factors and risk factors are important. Whilst associations between blood pressure (BP) and pain sensitivity in general are well documented [3], the relationship between headache and BP is being debated [4]. Although headache has often been reported previously particularly amongst hypertensive patients [5,6], more recent epidemiological studies have shown an inverse relationship between BP and Correspondence: C. F. Fagernæs, Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim 7489, Norway (tel.: +4795287210; fax: +47 73 59 87 95; e-mail: [email protected]).
© 2014 The Author(s) European Journal of Neurology © 2014 EAN
headache [7–13], supporting a phenomenon called hypertension-associated hypalgesia [14]. The majority of previous epidemiological studies, however, are cross-sectional or lack a validated definition of a headache-free population at baseline [9,10]. Thus, prospective large-scale population-based studies evaluating the influence of BP on the risk of developing the primary headaches migraine and tension-type headache (TTH) are needed. The present study is based upon two health surveys, carried out approximately 11 years apart, of the adult population in a Norwegian county. By selecting a headache-free population at baseline, the longitudinal design enables us to evaluate the possible relationships between BP and the subsequent risk for migraine and TTH at follow-up. A large number of recorded factors at baseline permits adjustments for potential confounders such as
2
C. F. Fagernæs et al.
body mass index (BMI), education, anxiety and depression, smoking, physical activity and cholesterol levels.
through the necessary BP measures. Amongst these, 6779 were women and 7073 were men. Headache diagnoses in HUNT 3
Methods Study design
The study was carried out as a prospective cohort study based on data from two large health surveys with a time interval of approximately 11 years. The population at risk was defined as headache free at baseline, and the subjects were not using antihypertensive medication. Subjects
The Nord-Trondelag Health Survey (HUNT) has been conducted in 1984–1986 (HUNT 1), in 1995– 1997 (HUNT 2) and in 2006–2008 (HUNT 3). All surveys incorporate comprehensive questionnaires regarding health history, and the participants were invited to a clinical examination involving the measurement of weight, height, BP and the taking of blood samples. In HUNT 2 and HUNT 3 the entire population of the Nord-Trondelag County aged 20 years of age or more was invited to complete extensive questionnaires, including similar phrased questions on headache. Subjects who answered ‘yes’ to the screening question in HUNT 2 ‘Have you suffered from headache during the last 12 months?’ were classified as headache sufferers. Those who answered ‘no’ comprise the headache-free group defined as the population at risk. The validity of the questionnairebased status of being headache free has previously been reported with a sensitivity of 83% and specificity of 85% [j = 0.57, 95% confidence interval (CI) 0.41– 0.73] [15]. In HUNT 2, 65 257 persons (70%) out of 92 566 invited participated (Fig. 1). Amongst these, 51 856 indicated whether they suffered from headache or not. In HUNT 3, 93 860 persons were invited and 39 690 of them (42%) answered the questions regarding headache. Amongst the 65 257 persons who participated in HUNT 2, 8545 had died and 4357 had moved out of the county during the time between HUNT 2 and HUNT 3. In all, 40 255 persons participated in both HUNT 2 and HUNT 3. Amongst these, 26 197 (65%) had answered the questions regarding headache in both HUNT 2 and HUNT 3, with the population at risk of headache counting 13 852 individuals (Fig. 1). These individuals did not report headache in HUNT 2, were not current users of antihypertensive medication at HUNT 2 and had gone
The questionnaire in HUNT 3 contained in total 14 questions regarding headache and was designed to determine whether the person suffered from headache in accordance with the International Classification of Headache Disorders, second edition (ICHD-II), criteria for migraine and TTH [16]. Details of the questions have been published previously [17]. The diagnoses were mutually exclusive, with TTH taking priority over probable migraine, i.e. patients fulfilling both diagnoses were classified as TTH. A category of unclassified headache emerged as an exclusion diagnosis, defined by a positive answer on the headache screening question but without the necessary characteristics to be classified as any of the other diagnoses. The merged group of ‘any headache’ consisted of individuals with migraine, probable migraine, TTH or unclassified headache. The validity of these questionnaire-based diagnoses has been reported previously [17]: for any headache, the sensitivity was 88% and specificity 86% (j = 0.70, 95% CI 0.61–0.79); for migraine, the sensitivity was 51% and specificity 95% (j = 0.50, 95% CI 0.32–0.68); and for TTH ≥ 1 day per month, the sensitivity was 96% and specificity 0.69% (j = 0.44, 95% CI 0.30–0.58). Exposure and covariate assessment (HUNT 2 variables)
Systolic BP (SBP) and diastolic BP (DBP) were measured by specially trained nurses using an oscillometric method with Dinamap 845XT. The participants were seated, and BP was measured after at least 4 min rest with the cuff placed on the right upper arm. The cuff was inflated three times, with an interval of at least 1 min. The values used constituted the mean of the second and third measurements. Pulse pressure (PP) was calculated by subtracting the DBP from the SBP. The SBP was categorized as
doi:10.1111/ene.12547
Blood pressure as a risk factor for headache and migraine: a prospective population-based study C. F. Fagernæsa, I. Heuchb, J.-A. Zwartb,c, B. S. Winsvoldb,c, M. Lindea,d and K. Hagena,d a
Department of Neuroscience, Norwegian University of Science and Technology, Trondheim; bDepartment of Neurology and FORMI, Oslo University Hospital, Oslo; cInstitute of Clinical Medicine, University of Oslo, Oslo; and dNorwegian National Headache Centre, St Olavs University Hospital, Trondheim, Norway
Keywords:
blood pressure, headache, hypertensionassociated hypalgesia, migraine Received 27 February 2014 Accepted 2 July 2014
Background and purpose: During the past decade, several population-based studies have found an inverse association between blood pressure (BP) and headache. However, most of them have a cross-sectional design or lack a validated definition of a headache-free population at baseline. Therefore, additional population-based studies using a clearly defined headache-free population and a prospective design are warranted. Methods: Data from two large epidemiological studies, the Nord-Trondelag Health Survey 1995–1997 (HUNT 2) and 2006–2008 (HUNT 3), were used to evaluate the association between BP (systolic, diastolic and pulse pressure) at baseline and headache (migraine and tension type headache) at follow-up. Results: An inverse relationship was found between all three BP measures at baseline in HUNT 2 and any headache in HUNT 3, more evident for systolic BP [odds ratio (OR) 0.90 per 10 mmHg increase in systolic BP, 95% confidence interval (CI) 0.87–0.93, P < 0.001] and pulse pressure (OR 0.84 per 10 mmHg increase in pulse pressure, 95% CI 0.80–0.89, P < 0.001) than for diastolic BP (OR 0.92 per 10 mmHg increase in diastolic BP, 95% CI 0.87–1.00, P = 0.036). The most robust finding, evident for both sexes, was that increased pulse pressure was linked to decreased prevalence of both migraine and tension type headache. Conclusion: An inverse relationship between BP and subsequent development of headache was confirmed in this large-scale population-based cohort study. Nevertheless, further research is needed to investigate the underlying mechanisms explaining these findings.
Introduction Headache is a major societal health problem and a cause of large monetary losses [1,2]. In order to understand the causes behind headache, investigations of protective factors and risk factors are important. Whilst associations between blood pressure (BP) and pain sensitivity in general are well documented [3], the relationship between headache and BP is being debated [4]. Although headache has often been reported previously particularly amongst hypertensive patients [5,6], more recent epidemiological studies have shown an inverse relationship between BP and Correspondence: C. F. Fagernæs, Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim 7489, Norway (tel.: +4795287210; fax: +47 73 59 87 95; e-mail: [email protected]).
© 2014 The Author(s) European Journal of Neurology © 2014 EAN
headache [7–13], supporting a phenomenon called hypertension-associated hypalgesia [14]. The majority of previous epidemiological studies, however, are cross-sectional or lack a validated definition of a headache-free population at baseline [9,10]. Thus, prospective large-scale population-based studies evaluating the influence of BP on the risk of developing the primary headaches migraine and tension-type headache (TTH) are needed. The present study is based upon two health surveys, carried out approximately 11 years apart, of the adult population in a Norwegian county. By selecting a headache-free population at baseline, the longitudinal design enables us to evaluate the possible relationships between BP and the subsequent risk for migraine and TTH at follow-up. A large number of recorded factors at baseline permits adjustments for potential confounders such as
2
C. F. Fagernæs et al.
body mass index (BMI), education, anxiety and depression, smoking, physical activity and cholesterol levels.
through the necessary BP measures. Amongst these, 6779 were women and 7073 were men. Headache diagnoses in HUNT 3
Methods Study design
The study was carried out as a prospective cohort study based on data from two large health surveys with a time interval of approximately 11 years. The population at risk was defined as headache free at baseline, and the subjects were not using antihypertensive medication. Subjects
The Nord-Trondelag Health Survey (HUNT) has been conducted in 1984–1986 (HUNT 1), in 1995– 1997 (HUNT 2) and in 2006–2008 (HUNT 3). All surveys incorporate comprehensive questionnaires regarding health history, and the participants were invited to a clinical examination involving the measurement of weight, height, BP and the taking of blood samples. In HUNT 2 and HUNT 3 the entire population of the Nord-Trondelag County aged 20 years of age or more was invited to complete extensive questionnaires, including similar phrased questions on headache. Subjects who answered ‘yes’ to the screening question in HUNT 2 ‘Have you suffered from headache during the last 12 months?’ were classified as headache sufferers. Those who answered ‘no’ comprise the headache-free group defined as the population at risk. The validity of the questionnairebased status of being headache free has previously been reported with a sensitivity of 83% and specificity of 85% [j = 0.57, 95% confidence interval (CI) 0.41– 0.73] [15]. In HUNT 2, 65 257 persons (70%) out of 92 566 invited participated (Fig. 1). Amongst these, 51 856 indicated whether they suffered from headache or not. In HUNT 3, 93 860 persons were invited and 39 690 of them (42%) answered the questions regarding headache. Amongst the 65 257 persons who participated in HUNT 2, 8545 had died and 4357 had moved out of the county during the time between HUNT 2 and HUNT 3. In all, 40 255 persons participated in both HUNT 2 and HUNT 3. Amongst these, 26 197 (65%) had answered the questions regarding headache in both HUNT 2 and HUNT 3, with the population at risk of headache counting 13 852 individuals (Fig. 1). These individuals did not report headache in HUNT 2, were not current users of antihypertensive medication at HUNT 2 and had gone
The questionnaire in HUNT 3 contained in total 14 questions regarding headache and was designed to determine whether the person suffered from headache in accordance with the International Classification of Headache Disorders, second edition (ICHD-II), criteria for migraine and TTH [16]. Details of the questions have been published previously [17]. The diagnoses were mutually exclusive, with TTH taking priority over probable migraine, i.e. patients fulfilling both diagnoses were classified as TTH. A category of unclassified headache emerged as an exclusion diagnosis, defined by a positive answer on the headache screening question but without the necessary characteristics to be classified as any of the other diagnoses. The merged group of ‘any headache’ consisted of individuals with migraine, probable migraine, TTH or unclassified headache. The validity of these questionnaire-based diagnoses has been reported previously [17]: for any headache, the sensitivity was 88% and specificity 86% (j = 0.70, 95% CI 0.61–0.79); for migraine, the sensitivity was 51% and specificity 95% (j = 0.50, 95% CI 0.32–0.68); and for TTH ≥ 1 day per month, the sensitivity was 96% and specificity 0.69% (j = 0.44, 95% CI 0.30–0.58). Exposure and covariate assessment (HUNT 2 variables)
Systolic BP (SBP) and diastolic BP (DBP) were measured by specially trained nurses using an oscillometric method with Dinamap 845XT. The participants were seated, and BP was measured after at least 4 min rest with the cuff placed on the right upper arm. The cuff was inflated three times, with an interval of at least 1 min. The values used constituted the mean of the second and third measurements. Pulse pressure (PP) was calculated by subtracting the DBP from the SBP. The SBP was categorized as
