How Common Are Comorbidities in Chronic Versus Episodic Migraine?

LOS ANGELES—Significantly more patients with chronic migraine versus episodic migraine report cardiovascular, respiratory, gastrointestinal, psychiatric, and sleep-related symptoms and conditions, according to research presented at the 70th Annual Meeting of the American Academy of Neurology.

Certain comorbidities, including allergies, insomnia, and neck pain, have relative frequencies in chronic migraine that are at least 10% greater than in episodic migraine. “Mechanisms explaining this association might include direct causality (eg, chronic migraine causes the comorbidity), reverse causality (eg, the condition increases chronic migraine risk), and shared genetic or environmental risk factors,” said Richard B. Lipton, MD, Edwin S. Lowe Chair in Neurology at Albert Einstein College of Medicine in New York, and colleagues. Detection bias also may contribute to the association, they said.

Examining Relative Frequencies

Migraineurs often present with concomitant conditions that may exacerbate the disease, and many comorbidities occur more frequently in chronic migraine than in episodic migraine. To replicate and extend research on comorbid medical conditions in a systematically recruited sample of people with episodic and chronic migraine, Dr. Lipton and colleagues analyzed data from the Chronic Migraine Epidemiology and Outcomes (CaMEO) Study, a prospective web-based survey designed to characterize self-reported headache symptoms and severity in a representative sample of people with migraine in the United States.

Richard B. Lipton, MD

The CaMEO study included a comorbidities-and-endophenotypes module that asked respondents whether they ever had specific symptoms or conditions and, if present, whether they had been confirmed or diagnosed by a doctor. The investigators analyzed self-reported data for symptoms easily identified by respondents and physician-diagnosed data for conditions that required a medical diagnosis. The researchers used chi-squared analysis to compare the relative frequencies of symptoms and conditions. Percentages for female-specific conditions (eg, polycystic ovary syndrome) were calculated by comparison with female migraineurs. Dr. Lipton and colleagues presented data about respiratory, sleep disorder, cardiovascular, and gastrointestinal comorbidities in one study and data about pain, psychiatric, and endocrine or neurologic comorbidities in another study.

In all, 16,763 CaMEO respondents with migraine received the comorbidities-and-endophenotypes module, and 12,810 provided valid responses. The analysis included 1,111 respondents (8.7%) with chronic migraine (ie, 15 or more headache days per month for more than three months) and 11,699 (91.3%) with episodic migraine (ie, fewer than 15 headache days per month). Compared with the episodic migraine group, the chronic migraine group had a similar mean age (41.3 vs 41.9), was more likely to be female (74.2% vs 81.5%), was more likely to be white (84.0% vs 88.7%), and had a higher mean BMI (27.7 kg/m2 vs 28.7 kg/m2). Compared with respondents with episodic migraine, respondents with chronic migraine more frequently reported allodynia, generalized anxiety disorder, and major depression and had a greater mean Migraine Disability Assessment Scale (MIDAS) score.

A Range of Symptoms and Conditions

Of the 31 respiratory, sleep disorder, cardiovascular, and gastrointestinal comorbidities assessed, the relative frequencies were significantly higher in chronic migraine for 93.5%. The following five conditions or groups of conditions had relative frequencies at least 10% higher in chronic migraine than episodic migraine: allergies, hay fever, or allergic rhinitis (61.2% vs 51.2%); sinusitis or sinus infection (63.5% vs 52.7%); insomnia (50.2% vs 35.6%); vertigo, dizziness, or balance problems (29.7% vs 17.8%); and gastroesophageal reflux disease (24.4% vs 14.3%).

Of the 28 pain, psychiatric, and endocrine or neurologic comorbidities assessed, the relative frequencies were significantly higher in chronic migraine for 85.7%. The following five conditions had relative frequencies more than 10% higher in chronic migraine than in episodic migraine: chronic back pain (37.6% vs 22.5%), chronic pain (22.2% vs 7.4%), neck pain (55.3% vs 38.1%), anxiety (42.2% vs 25.7%), and depression (45.6% vs 28.1%).

The Likelihood of Medication Overuse

Of the eight endocrine or neurologic comorbidities assessed (ie, hyperhidrosis, diabetes, seizures, spasticity, underactive thyroid or thyroid medication, cervical dystonia, gout, and polycystic ovary syndrome), all but gout and polycystic ovary syndrome had significantly higher relative frequencies in chronic migraine.

When the researchers used latent class analysis to identify natural subgroups of migraine based on profiles of comorbidities and concomitant conditions, they found that a subgroup with the most comorbidities was more likely to include individuals with chronic migraine (23.1% vs 4.8%) and had greater proportions of individuals with grade IV MIDAS scores (ie, severe disability; 48.1% vs 15.1%), allodynia (67.6% vs 38.3%), medication overuse (36.4% vs 8.9%), and aura (40.1% vs 23.9%), compared with a subgroup with the fewest comorbidities.

The studies were funded by Allergan.

—Jake Remaly

Suggested Reading

Adams AM, Serrano D, Buse DC, et al. The impact of chronic migraine: The Chronic Migraine Epidemiology and Outcomes (CaMEO) Study methods and baseline results. Cephalalgia. 2015;35(7):563-578.