Methodological Issues in Studying Rates and Predictors of Migraine Progression and Remission

Risk factors for migraine disease progression: a narrative review for a patient-centered approach

BACKGROUND

In individuals with migraine, attacks may increase in frequency, severity, or both. Preventing migraine progression has emerged as a treatment goal in headache subspecialty practice, but there may be less awareness in general neurology or primary care settings where most people with migraine who seek treatment consult. Herein, we review the definition of and risk factors for migraine progression and consider strategies that could reduce its risk.

METHODS

A group of headache expert healthcare professionals, clinicians, and researchers reviewed published evidence documenting factors associated with increased or decreased rates of migraine progression and established expert opinions for disease management recommendations. Strength of evidence was rated as good, moderate, or based solely on expert opinion, using modified criteria for causation developed by AB Hill.

RESULTS

Migraine progression is commonly operationally defined as the transition from ≤ 15 to ≥ 15 monthly headache days among people with migraine; however, this does not necessarily constitute a fundamental change in migraine biology and other definitions should be considered. Established and theoretical key risk factors for migraine progression were categorized into five domains: migraine disease characteristics, treatment-related factors, comorbidities, lifestyle/exogenous factors, and demographic factors. Within these domains, good evidence supports the following risk factors: poorly optimized acute headache treatment, cutaneous allodynia, acute medication overuse, selected psychiatric symptoms, extra-cephalic chronic pain conditions, metabolism-related comorbidities, sleep disturbances, respiratory conditions, former/current high caffeine intake, physical inactivity, financial constraints, tobacco use, and personal triggers as risk factors. Protective actions that may mitigate migraine progression are sparsely investigated in published literature; our discussion of these factors is primarily based on expert opinion.

CONCLUSIONS

Recognizing risk factors for migraine progression will allow healthcare providers to suggest protective actions against migraine progression (Supplementary Fig. 1). Intervention studies are needed to weight the risk factors and test the clinical benefit of hypothesized mitigation strategies that emerge from epidemiological evidence.

Fremanezumab versus placebo for migraine prevention in patients with documented failure to up to four migraine preventive medication classes (FOCUS): a randomised, double-blind, placebo-controlled, phase 3b trial

BACKGROUND

Antibodies targeting calcitonin gene-related peptide (CGRP) or its receptor have shown efficacy in the prevention of migraine attacks. We investigated the efficacy and tolerability of fremanezumab, a fully humanised CGRP antibody, in patients with migraine who had previously not responded to two to four classes of migraine preventive medications.

METHODS

The randomised, double-blind, placebo-controlled, parallel-group, phase 3b FOCUS trial was done at 104 sites (including hospitals, medical centres, research institutes, and group practice clinics) across Belgium, the Czech Republic, Denmark, Finland, France, Germany, Italy, the Netherlands, Poland, Spain, Sweden, Switzerland, the UK, and the USA. We enrolled participants aged 18-70 years with episodic or chronic migraine who had documented failure to two to four classes of migraine preventive medications in the past 10 years. Failure was defined as no clinically meaningful improvement after at least 3 months of therapy at a stable dose, as per the treating physician's judgment; discontinuation because of adverse events that made treatment intolerable; or treatment contraindicated or unsuitable for the preventive treatment of migraine for the patient. Participants were randomly assigned (1:1:1) by electronic interactive response technology to subcutaneously administered quarterly fremanezumab (month 1, 675 mg; months 2 and 3: placebo), monthly fremanezumab (month 1: 225 mg in episodic migraine and 675 mg in chronic migraine; months 2 and 3: 225 mg in both migraine subgroups), or matched monthly placebo for 12 weeks. The primary outcome was mean change from baseline in the monthly average number of migraine days during the 12-week treatment period. This trial is registered with ClinicalTrials.gov, number NCT03308968, and is now completed.

FINDINGS

Between Nov 10, 2017, and July 6, 2018, 838 participants with episodic (329 [39%]) or chronic (509 [61%]) migraine were randomly assigned to placebo (n=279), quarterly fremanezumab (n=276), or monthly fremanezumab (n=283). Reductions from baseline in monthly average migraine days over 12 weeks were greater versus placebo (least-squares mean [LSM] change -0·6 [SE 0·3]) with quarterly fremanezumab (LSM change -3·7 [0·3]; LSM difference vs placebo -3·1 [95% CI -3·8 to -2·4]; p<0·0001) and with monthly fremanezumab (LSM change -4·1 [0·34]; LSM difference vs placebo -3·5 [-4·2 to -2·8]; p<0·0001). Adverse events were similar for placebo and fremanezumab. Serious adverse events were reported in four (1%) of 277 participants with placebo, two (<1%) of 276 with quarterly fremanezumab, and four (1%) of 285 with monthly fremanezumab.

INTERPRETATION

Fremanezumab was effective and well tolerated in patients with difficult-to-treat migraine who had previously not responded to up to four classes of migraine preventive medications.

FUNDING

Teva Pharmaceuticals.

Remission of chronic headache: An 11-year follow-up study. Data from the Nord-Trøndelag Health Surveys 1995-1997 and 2006-2008

OBJECTIVES

To estimate remission rates of chronic headache and predictors of remission.

METHODS

In this longitudinal population-based cohort study, we used validated headache questionnaire data from the second (1995-1997, baseline; n = 51,856 aged ≥ 20 years, response rate: 55%) and third wave (2006-2008, follow-up, response rate: 42%) of the Nord-Trøndelag Health Study. Chronic headache was defined as ≥15 headache days/month during the last year. Chronic headache remission was defined as headache less than 15 days/month at follow-up. Potential predictors of remission were evaluated using logistic regression.

RESULTS

At baseline, 1266 (2.4%) participants reported chronic headache. Of these, 605 (48%) answered headache questions at follow-up. Remission was observed in 452 (74.7%), the proportion being almost identical in men and women (74.4% vs. 74.9, p = 0.92). In analyses adjusting for age, gender and education level, remission at follow-up was more than two times more likely among individuals without medication overuse headache (OR = 2.4, 95% CI 1.7-3.6) and without chronic musculoskeletal complaints (OR = 2.9, 95% CI 1.5-5.0) at baseline.

CONCLUSIONS

In this longitudinal population-based cohort study, three-quarters of chronic headache participants remitted from chronic headache. Remission was associated with no medication overuse headache and no chronic musculoskeletal complaints at baseline.

Migraine

Migraine is a chronic paroxysmal neurological disorder characterised by multiphase attacks of head pain and a myriad of neurological symptoms. The underlying genetic and biological underpinnings and neural networks involved are coming sharply into focus. This progress in the fundamental understanding of migraine has led to novel, mechanism-based and disease-specific therapeutics. In this Seminar, the clinical features and neurobiology of migraine are reviewed, evidence to support available treatment options is provided, and emerging drug, device, and biological therapies are discussed.

Complete detoxification is the most effective treatment of medication-overuse headache: A randomized controlled open-label trial

Background There is lack of evidence on how to detoxify medication-overuse headache. Aim To compare the effect of complete stop of acute medication with restricted intake. Methods Medication-overuse headache patients were included in a prospective, outpatient study and randomized to two months' detoxification with either a) no analgesics or acute migraine-medication (program A), or b) acute medication restricted to two days/week (program B). Detoxification was followed by preventives if indicated. Patients were followed up at 2, 6 and 12 months. Percentage reduction in headache days/month after 6 months was the primary outcome. Results We included 72 medication-overuse headache patients with a primary migraine and/or tension-type headache diagnosis. Fifty-nine completed detoxification, 58 (81%) were followed up at month 6 and 53 (74%) at month 12. At month 6, program A reduced headache days/month by 46% (95% CI 34-58) compared with 22% (95% CI 11-34) in program-B ( p = 0.005), and 70% in program A versus 42% in program B were reverted to episodic headache ( p = 0.04). Migraine-days/month were reduced by 7.2 in program A ( p < 0.001) and 3.6 in program B ( p = 0.002) after 6 months. Conclusion Both detoxification programs were very effective. Detoxification without analgesics or acute migraine-medication was the most effective program. Trial registration Clinicaltrials.gov (NCT02903329).

Medication overuse headache: An entrenched idea in need of scrutiny

It is a widely accepted idea that medications taken to relieve acute headache pain can paradoxically worsen headache if used too often. This type of secondary headache is referred to as medication overuse headache (MOH); previously used terms include rebound headache and drug-induced headache. In the absence of consensus about the duration of use, amount, and type of medication needed to cause MOH, the default position is conservative. A common recommendation is to limit treatment to no more than 10 or 15 days per month (depending on medication type) to prevent headache frequency progression. Medication withdrawal is often recommended as a first step in treatment of patients with very frequent headaches. Existing evidence, however, does not provide a strong basis for such causal claims about the relationship between medication use and frequent headache. Observational studies linking treatment patterns with headache frequency are by their nature confounded by indication. Medication withdrawal studies have mostly been uncontrolled and often have high dropout rates. Evaluation of this evidence suggests that only a minority of patients required to limit the use of symptomatic medication may benefit from treatment limitation. Similarly, only a minority of patients deemed to be overusing medications may benefit from withdrawal. These findings raise serious questions about the value of withholding or withdrawing symptom-relieving medications from people with frequent headaches solely to prevent or treat MOH. The benefits of doing so are smaller, and the harms larger, than currently recognized. The concept of MOH should be viewed with more skepticism. Until the evidence is better, we should avoid dogmatism about the use of symptomatic medication. Frequent use of symptom-relieving headache medications should be viewed more neutrally, as an indicator of poorly controlled headaches, and not invariably a cause.

Chronic Migraine: An Update on Physiology, Imaging, and the Mechanism of Action of Two Available Pharmacologic Therapies

Several lines of research support the hypothesis that migraine is a spectrum of illness, with clinical symptoms that vary along a continuum from episodic migraine to chronic migraine. Physiologic changes may result in episodic migraine evolving into chronic migraine over months to years in susceptible individuals. With chronification, headache frequency increases, becoming more disabling and less responsive to therapy. Neurophysiologic and functional imaging research has reported that chronic migraine may be associated with severity‐specific metabolic, functional, and structural abnormalities in the brainstem. Without longitudinal studies, it is unclear whether these changes may represent a continuum of individual progression and/or are reversible. Furthermore, chronic migraine is associated with larger impairments in cortical processing of sensory stimuli when compared with episodic migraine, possibly caused by more pronounced cortical hyperexcitability.

Progressive changes in nociceptive thresholds and subsequent central sensitization due to recurrent migraine attacks in vulnerable individuals contribute to the chronic migraine state. This may result in changes to baseline neurologic function between headache attacks, evident in both electrophysiological and functional imaging research. Patients experiencing migraine chronification may report increased non‐headache pain, fatigue, psychiatric disorders (eg, depression, anxiety), gastrointestinal complaints, and other somatic conditions associated with their long‐term experience with migraine pain.

Recent research provides a foundation for differentiating episodic and chronic migraine based on neurophysiologic and neuroimaging tools. In this literature review, we consider these findings in the context of models designed to explain the physiology and progression of episodic migraine into chronic migraine, and consider treatment of chronic migraine in susceptible individuals. Advances in pharmacotherapy provide treatment options for chronic migraine. Of the currently available treatment options, only onabotulinumtoxinA and topiramate have received regulatory approval and have demonstrated efficacy in patients with chronic migraine, although the exact mechanisms of action are not fully elucidated.

"Headache Tools to Stay in School": Assessment, Development, and Implementation of an Educational Guide for School Nurses

BACKGROUND

Headache is the most common type of pain reported in the pediatric population, and chronic headache is an increasingly prevalent and debilitating pain condition in children and adolescents. With large numbers of students experiencing acute headaches and more students with chronic headache reentering typical school settings, greater availability of tailored evidence-based practice guidelines for school nurses is imperative.

METHODS

A 2-armed study was developed to assess the need for and evaluate the use and favorability of a headache-driven school nurse guide. Students and their parents were first surveyed on their school nurse's headache knowledge and management skills. School nurses were also interviewed on their desire for a headache educational tool. This feedback aided in developing a headache resource guide. Next, the guide was distributed to school nurses who provided feedback after a 3-month trial.

RESULTS

Results indicate that "Headache Tools to Stay in School" is a useful resource in facilitating communication among health care providers, students, families, and school personnel on how to best meet the complex needs of students with headaches.

CONCLUSIONS

Given the guide's favorability, we encourage school nurses to demand the creation of additional evidence-based resources. Continued dissemination of this guide may improve students' headache management under the informed care of school nurses, and may encourage the development of more evidence-based guides across various medical conditions.

Rethinking headache chronification

The objective of this series is to examine several threats to the interpretation of headache chronification studies that arise from methodological issues. The study of headache chronification has extensively used longitudinal designs with 2 or more measurement occasions. Unfortunately, application of these designs, when combined with the common practice of extreme score selection as well as the extant challenges in measuring headache frequency rates (eg, unreliability, regression to the mean), induces substantive threats to accurate interpretation of findings. Partitioning the amount of observed variance in rates of chronification and remission attributable to regression artifacts is a critical yet previously overlooked step to learning more about headache as a potentially progressive disease. In this series on rethinking headache chronification, we provide an overview of methodological issues in this area (this paper), highlight the influence of rounding error on estimates of headache frequency (second paper), examine the influence of random error and regression artifacts on estimates of chronification and remission (third paper), and consider future directions for this line of research (fourth paper).

Candidate-gene association study searching for genetic factors involved in migraine chronification

INTRODUCTION

Chronic migraine (CM) is at the severe end of the clinical migraine spectrum, but its genetic background is unknown. Our study searched for evidence that genetic factors are involved in the chronification process.

METHODS

We initially selected 144 single-nucleotide polymorphisms (SNPs) from 48 candidate genes, which we tested for association in two stages: The first stage encompassed 262 CM patients, the second investigated 226 patients with high-frequency migraine (HFM). Subsequently, SNPs with p values < 0.05 were forwarded to the replication stage containing 531 patients with CM or HFM.

RESULTS

Eight SNPs were significantly associated with CM and HFM in the two-stage phase. None survived replication in the third stage.

DISCUSSION

We present the first comprehensive genetic association study for migraine chronification. There were no significant findings. Future studies may benefit from larger, genome-wide data sets or should use other genetic approaches to identify genetic factors involved in migraine chronification.

Influence of random measurement error on estimated rates of headache chronification and remission

OBJECTIVE

To examine the potential influence of random measurement error on estimated rates of chronification and remission.

BACKGROUND

Studies of headache chronification and remission examine the proportion of headache sufferers that move across a boundary of 15 headache days per month between 2 points in time. At least part of that apparent movement may represent measurement error or random variation in headache activity over time.

METHODS

A mathematical simulation was conducted to examine the influence of varying degrees of measurement error on rates of chronic migraine onset and remission. Using data from the American Migraine Prevalence and Prevention Study, we estimated a starting distribution of headache days from 0 to 30 in the migraine population. Assuming various levels of measurement error, we then simulated 2 sets of data for Time 1 and Time 2. The "individuals" in this study were assumed to have no real change in headache frequency from Time 1 to Time 2. The observed variations in headache frequency were those influenced by imputed random variance to resemble typical measurement error or natural variability. Using this simulation approach, we estimated the amount of chronification and remission rates that might be attributed simply to statistical artifacts such as unreliability or regression to the mean.

RESULTS

As the degree of measurement error increased, the amounts of illusory chronification and remission increased substantially. For example, if the headache frequency of sufferers randomly varies by only 2 headache days each month due to chance alone, a substantial degree of illusory chronification (0.6% to 1.3%) and illusory remission (10.3% to 23.5%) rates are expected simply due to random variation.

CONCLUSIONS

Random variation, without real change, has the potential to influence estimated rates of progression and remission in longitudinal migraine studies. The magnitude of random variation needed to fully reproduce observed rates of progression and remission are implausibly large. Recommendations are offered to improve estimation of rates of progression and remission, reducing the influence of random variation.