Abstract
Objective
The objective of this article is to evaluate whether statin use and vitamin D status is associated with severe headache or migraine in a nationally representative sample.
Methods
We conducted a cross-sectional study of US individuals aged ≥40 years for whom information on statin use, serum 25-hydroxy vitamin D (25(OH)D), and self-reported severe headache or migraine had been collected. We calculated prevalence estimates of headache according to statin and 25(OH)D, and conducted adjusted logistic regression analyses stratified by the median 25(OH)D (≤57 and >57 nmol/l).
Results
Among 5938 participants, multivariable-adjusted logistic regression showed that statin use was significantly associated with a lower prevalence of severe headache or migraine (OR 0.67; 95% CI 0.46, 0.98, p = 0.04). We found a significant interaction between statin use and 25(OH)D with the prevalence of severe headache or migraine (p for interaction = 0.005). Among participants who had serum 25(OH)D > 57 nmol/l, statin use was associated with a multivariable-adjusted odds ratio of 0.48 (95% CI 0.32, 0.71, p = 0.001) for having severe headache or migraine. Among those with 25(OH)D ≤ 57 nmol/l, no significant association was observed between statin use and severe headache or migraine.
Conclusion
Statin use in those with higher serum vitamin D levels is significantly associated with lower odds of having severe headache or migraine.
Introduction
Use of statin medications has been associated with both increased (1–3) and decreased (4,5) risk for migraine and headache. The association of vitamin D status and headache is also mixed, with some (6–8), but not all (9), observational studies showing low vitamin D levels may be associated with headache. Based on observations that statin-associated muscle pain is significantly less likely to occur in patients when vitamin D levels are higher (10), we hypothesized that statins may have a variable effect on headache related to an interaction between statin and vitamin D status. Specifically, we predicted that use of statins among individuals with low vitamin D status would be associated with a higher prevalence of experiencing severe headache or migraine, and that use of statin by individuals with higher vitamin D would be associated with a lower prevalence of severe headache or migraine.
There is currently no agreed on definition for optimal serum vitamin D levels (11). A 25(OH)D level <37.5 nmol/l or <50 nmol/l has frequently been used to define vitamin D deficiency (12,13). For optimal health, some experts advocate attaining a 25(OH)D level of at least 75 nmol/l (14).
Methods
This was a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES), a stratified multistage probability survey of the civilian, non-institutionalized United States population. The NHANES includes an in-home interview to collect demographic and detailed health information, followed by examination and laboratory testing in a mobile examination center. Public-use data files for this study were downloaded from the NHANES Website (http://www.cdc.gov/nchs/nhanes.htm). Consent was obtained from participants by the National Center for Health Statistics (NCHS) after approval by the NHANES Institutional Review Board/NCHS Research Ethics Review Board. These analyses were approved for exemption by our institutional review board based on 45 CFR 46.101(b) regulating the use of de-identified data.
We analyzed data from the 2001–2004 NHANES, as those were the only years for which information on primary exposures of interest, serum 25-hydroxy vitamin D (25(OH)D) and statin use, as well as the outcome, severe headache or migraine, was available. We restricted our analyses to participants ≥40 years, because people younger than 40 years rarely use statins.
During the in-home interview, participants were asked if they had severe headache or migraine in the three months prior to the interview. Information on statin and other prescription medications was queried from all participants by first asking if they used any prescription medication; those who answered in the affirmative were asked to show medication containers to the interviewer to ensure correct recording of medication names. Measurements of serum 25(OH)D were performed at the Centers for Disease Control in Atlanta, GA, using the DiaSorin RIA kit (Stillwater, MN). Adjusted measures of 25(OH)D were used, taking into account assay drifts due to reagent and calibration lot-to-lot variability over time (15). We included, a priori, stratification by vitamin D status to examine the hypothesized interaction and dichotomized 25(OH)D by the median, weighted to account for the population sampled (≤57 and >57 nmol/l).
Other covariates
Principal confounders previously known or suspected to be associated with statin use or to affect the relationship between statin use and vitamin D were chosen a priori and included simultaneously in all multivariable adjusted models. These included age (continuous), sex (male/female), race/ethnicity (non-Hispanic white, non-Hispanic black, and other), educational attainment (less than high school diploma, high school diploma, more than high school diploma), self-reported health status (excellent/very good, good, poor/fair), physical activity (sedentary, moderate activity, vigorous activity), smoking (never, former, current), alcohol intake (continuous, average servings of drinks/week over the past year), body mass index (BMI) (continuous, based on measured height and weight), coronary heart disease (defined as having been told by a doctor/other health professional of a diagnosis of coronary artery disease, prior myocardial infarction, or angina), history of stroke, number of times seen by a doctor or other health professional during the past year (zero to one, two to three, or four or more times), number of concurrent medications used (continuous), use of specific medications that might be associated with pain relief and/or medication-overuse headache including: daily/near daily over-the-counter (OTC) analgesics (not including aspirin used alone), prescription nonsteroidal drugs, oral steroids, opioids, and use of specific medications commonly used for cardiovascular conditions, some of which may also prevent migraine including: beta-blockers, calcium channel blockers, angiotensin-converting-enzyme inhibitors or angiotensin II receptor blockers (ACE inhibitors/ARBs), and daily/near daily aspirin use. Daily/near daily use of aspirin or over-the-counter analgesics was defined as using these agents 15 days or more per month.
Sensitivity and post hoc analyses
We performed sensitivity analyses to explore if use of other medications or conditions influenced our results. Adjusting for all variables included in the main model we added, in separate models, the following: measured systolic blood pressure; diabetes (defined based on self-report of a doctor’s/health professional’s diagnosis, or measured glucose >200 mg/dl, or use of an antidiabetic medication); self-report of “depression/anxiety/emotional problem” that caused participant to have any difficulty or need help with activities; and, as a secondary proxy for mental health conditions, reporting having seen a mental health professional in the past year. Additionally, we examined whether use of preventive migraine therapy (which individuals regularly seeing a physician might be more likely to be prescribed) altered our findings. To perform these analyses, cardiovascular medications (except for statin and aspirin) were removed from the main model to avoid redundancy, and medications found to have Level A, B, or C evidence for migraine prevention were included (16). Specifically, this variable was defined as use of at least one of any of the following: divalproex sodium, sodium valproate, topiramate, metoprolol, propranolol, timolol, amitriptyline, venlafaxine, atenolol, nadolol, lisinopril, candesartan, clonidine, guanfacine, carbamazepine, nebivolol, pindolol, and cyproheptadine. To assess if post-menopausal status or exogenous hormones altered the results, we performed analyses restricting models (1) to age greater than 55 years, and (2) to women ≥40 years, while adding a variable for use of estrogen-containing contraceptives or hormone replacement therapy. Finally, we performed post hoc analyses examining 25(OH)D as a continuous linear variable.
All analyses were performed in SAS 9.3 and STATA 12 statistical software using survey weights to represent the population and to account for the complex sample design, non-response, and planned over-sampling of selected populations. We calculated prevalence estimates of headache according to 25(OH)D levels and to statin use, and conducted multivariable logistic regression analyses to adjust for multiple confounders.
Results
Characteristics of the participants according to statin use (NHANES 2001–2004, ≥40 years).
NHANES: National Health and Nutrition Examination Survey; OTC analgesics: over-the-counter analgesics (not including aspirin used alone); NSAIDs: nonsteroidal anti-inflammatory drugs; ACE inhibitor/ARB: angiotensin-converting-enzyme inhibitors or angiotensin II receptor blockers.
Characteristics of the participants according to serum 25(OH)D (NHANES 2001–2004, ≥40 years).
NHANES: National Health and Nutrition Examination Survey; OTC analgesics: over-the-counter analgesics (not including aspirin used alone); NSAIDs: nonsteroidal anti-inflammatory drugs; ACE inhibitor/ARB: angiotensin-converting-enzyme inhibitors or angiotensin II receptor blockers.
The overall weighted prevalence of severe headache or migraine in this population was 20.1%. Figure 1 shows the weighted prevalence of severe headache or migraine in the population by age. Prevalence of severe headache or migraine varied between those who used statins and those who did not. Among 1069 statin users, 16.1% reported severe headache or migraine, compared to 20.9% of those who did not use a statin. Among those who had a 25(OH)D ≤ 57 nmol/l and those who had 25(OH)D > 57 nmol/l, the prevalence of severe headache or migraine was 21.1% and 19.1%, respectively.
Three-month prevalence of severe headache or migraine according to age (NHANES 2001–2004, ≥40 years). NHANES: National Health and Nutrition Examination Survey.
Figure 2 illustrates the prevalence of severe headache or migraine among statin users versus non-users according to quartiles of 25(OH)D. Among statin users, the prevalence of severe headache or migraine was highest among participants in the lowest quartile of 25(OH)D and was lowest among participants in the highest 25(OH)D quartiles. Among non-statin users, the prevalence of severe headache or migraine was not substantially different across 25(OH)D quartiles.
Three-month prevalence of severe headache or migraine among statin users and non-users according to serum 25(OH)D quartiles.
In multivariable analyses adjusted for all a priori covariates, we found a significant association between statin use and a lower prevalence of severe headache or migraine, adjusted odds ratio (OR): 0.67 (95% confidence interval (CI): 0.46, 0.98). Including an interaction term in the model between statin use and 25(OH)D ≤ or >57 nmol/l confirmed a statistically significant interaction between these factors, with a lower prevalence of severe headache or migraine for statin use and 25(OH)D > 57 nmol/l (p for interaction = 0.005). In post-hoc analysis, modeling 25(OH)D as a continuous linear variable attenuated the interaction between statin and 25(OH)D (p for interaction = 0.05).
Adjusted a odds ratios (OR) and 95% confidence intervals (CI) of the effect of statin and other cardiovascular medications on severe headache or migraine in the overall sample and stratified by vitamin D status (National Health and Nutrition Examination Survey, 2001–2004, ≥40 years).
Adjusted for all medications in above table and for age, sex, race/ethnicity (non-Hispanic white, non-Hispanic black, other), educational attainment (less than high school diploma, high school diploma, more than high school diploma), self-reported health status (excellent/very good, good, poor/fair), physical activity (sedentary, moderate, vigorous), smoking status (never, former, current), alcohol intake, body mass index, coronary heart disease, stroke, times seen by a health professional in last year (0–1, 2–3, ≥4), number of concurrent medications used, use of daily/near daily over-the-counter analgesics, use of prescription nonsteroidal drugs, use of opioids, and use of oral steroids.
bPrevalence of severe headache or migraine in each group: Overall sample, n = 1069; 25(OH)D ≤ 57 nmol/l, n = 675; 25(OH)D > 57 nmol/l, n = 394). ACE inhibitor/ARB: angiotensin-converting-enzyme inhibitors or angiotensin II receptor blockers.
Bold denotes significant findings at p value < 0.05.
Further adjustment for measured systolic blood pressure; diabetes; depression/anxiety; or having seen a mental health professional in the past year, and using alternative modeling to examine the use of preventive migraine medications, did not materially affect the results in the overall model or stratified models.
To account for the possibility that endogenous or exogenous estrogen influenced our results, we also performed multivariable adjusted models in subpopulations: (1) Restricting age to ≥55 years in men and women. These analyses revealed an OR of 0.62 (95% CI: 0.41, 0.95) for the effect of statin on the outcome of severe headache or migraine in the overall model, an OR of 0.82 (95%CI: 0.50, 1.37) for those with 25(OH)D ≤ 57 nmol/l, and an OR of 0.33 (95% CI: 0.17, 0.66) for those with 25(OH)D > 57 nmol/l; and (2) restricting the sample to women only, for ages ≥40 years, and including use of exogenous estrogen (defined as use of estrogen-containing contraception or hormone replacement therapy) as a covariate in the models. These analyses revealed an OR of 0.71 (95% CI: 0.43, 1.16) for the effect of statin on the outcome of severe headache or migraine in the overall model, an OR of 0.91 (95% CI: 0.52, 1.57) for those with 25(OH)D ≤ 57 nmol/l, and an OR of 0.43 (95% CI: 0.20, 0.91) for those with 25(OH)D > 57 nmol/l.
Discussion
In the presence of higher levels of vitamin D, statin use was associated with a significantly lower prevalence of severe headache or migraine. This association remains after adjusting for multiple confounders.
The outcome for this study, prevalence of severe headache or migraine in the prior three months, was based on self-report; therefore, we can interpret our findings only in the context of severe headache. However, considering that most headaches are classified as migraine when headache specialists evaluate headaches described by patients as severe (17), it is reasonable to propose that most headaches reported in this study were migraine. Other headaches likely include severe tension-type headache, and to a much lesser extent, uncommon primary and secondary headaches (18–20).
Options for migraine prophylaxis remain unsatisfactory, with patients citing lack of effectiveness and significant side effects as the most common reasons for discontinuing their use (21). Thus, efforts to identify more effective treatments with low side effects remain urgent. This current study supports the idea of investigating if statin and vitamin D supplementation could be an effective, well-tolerated therapy for preventing migraine.
The overall rationale for this study is based on the association between migraine with aura and the risk for developing vascular disease, most notably stroke and suggested associations between vascular diseases and any migraine (22–25), although the latter remains controversial. Statins have demonstrated benefits in preventing and improving vascular diseases via lipid (26) and lipid-independent (27–31) effects on the endothelium. As a hypothetical mechanism, endothelial dysfunction, which is a precursor to vascular disease, may be both a consequence of migraine and a possible cause/contributor of migraine pathogenesis (32). Evidence for endothelial dysfunction in migraine patients includes increased markers of inflammation (tumor necrosis factor (TNF)alpha, and interleukin (IL)-1) (33), thrombosis (von Willebrand factor (vWF) activity (34), and plasminogen activator antigen (32), and alterations in the nitric oxide pathway (35,36), which mediates vascular smooth muscle tone. Additionally, several studies have shown an association of migraine with increased augmentation index (AIx), a measure of arterial stiffness (37–41). Accordingly, in the context of migraine, statin may reduce attack frequency by improving endothelial function (42), arterial stiffness (28,43), and vascular tone (28), and through the ability to reduce inflammatory responses (44–48), and decrease platelet aggregation and thrombosis (49).
Statins are best known as cholesterol-lowering agents, and an association between hypercholesterolemia and migraine has previously been reported (50–54). However, the few studies that have further explored the association between cholesterol and frequency of migraine have not found a correlation (52,53). Therefore, it seems unlikely that statins might decrease migraine via a direct action on cholesterol reduction, suggesting further investigations on lipid-independent actions would be of most interest.
We did not find significant modification of statin’s effects by vitamin D when modeling 25(OH)D as a simple linear continuous variable; this was not surprising given prevailing evidence suggesting a threshold effect of vitamin D on various health outcomes (55). Regarding the observed interaction between statin and 25(OH)D > 57 nmol/l, it may be reasonable to speculate that the effects of statin are facilitated by vitamin D, which has overall anti-inflammatory effects on cytokines (56,57). Another speculation on how vitamin D might interact with statin to reduce migraine involves muscle pain, a suspected trigger of migraine when occurring in the neck (58). Muscle pain in general is common among statin users with low vitamin D level, but is significantly less common among statin users with higher vitamin D levels (10). Because the pathophysiology of migraine-associated muscle tenderness is largely unknown, more research is needed to understand whether and how statin and vitamin D interact to reduce migraine through actions on muscles.
Finally, it is possible that low vitamin D status serves as a surrogate marker for long-term disease states or long-term poor health in general, and those individuals with longer-term poor health or disease may be less likely to respond to pleiotropic effects of statin. Although we controlled for several health measures and health risks in this study, a cross-sectional study lacks the dimension of time. Therefore, investigation into the relationship between statin, vitamin D status, and migraine in large longitudinal cohorts and randomized, controlled trials would be of great interest.
Study limitations
First, this study included only people ≥40 years in order to evaluate statin use, thus our findings may not be generalizable to younger individuals with severe headache or migraine. Second, although we adjusted for several confounders, residual confounding may exist. Third, the outcome of having severe headache or migraine in the past three months was based on self-report. As noted above, no further information was available to discern headache classifications or apply International Classification Headache Disorders criteria. Thus, misclassification is possible. Fourth, although 25(OH)D showed a normal distribution, the range was relatively narrow, which prevented us from examining higher levels, e.g. 25(OH)D levels 75 nmol/l or higher, recommended by some for optimal health (14). Fifth, our findings of dichotomized versus linear models of 25(OH)D are consistent with the notion that the effect of 25(OH)D on statin use is nonlinear; however, the exact threshold at which severe headache or migraine may decrease remains unclear. Finally, as a cross-sectional study, this study cannot address causality or the direction of the association we observed between statin use and vitamin D with lower prevalence of severe headache or migraine.
Results from this study suggest the combination of statin treatment and vitamin D supplementation should be explored as a possible headache/migraine preventive. Additionally, among individuals using a statin who experience an increase in or worsening of migraine or headache, testing for vitamin D may be reasonable and, if vitamin D deficiency were to be identified, supplementation would be prudent.
Conclusion
Our preliminary findings indicate that people who have serum 25(OH)D > 57 nmol/l and use a statin have a lower prevalence of severe headache or migraine. It remains to be seen whether combined treatment with statin and vitamin D supplementation might serve as a therapy to prevent headache or migraine.
Clinical implications
Statins have a variable effect on the prevalence of severe headache or migraine that depends on vitamin D status. Statin use in those with higher serum vitamin D levels is significantly associated with a lower prevalence of having severe headache or migraine.
Footnotes
Funding
Dr Buettner’s time was supported by a National Institutes of Health (NIH) K23 Career Development Award (K23AR055664) and by the Department of Anesthesia and Critical Care, Beth Israel Deaconess Medical Center. Dr Burstein was supported by an NIH Award (R37 NS079678). The content is solely the responsibility of the authors and does not necessarily represent the official views of Harvard University and its affiliated academic health care centers or the National Institutes of Health.
Conflicts of interest
Dr Buettner and Dr Burstein have applied for a patent for the combination of statin and vitamin D as a prophylactic treatment in migraine. Dr Burstein has received funding from the NIH, Merck, Allergan and GlaxoSmithKline.
