A study sought to test the hypothesis that in persons with episodic migraine, asthma is a risk factor for the onset of chronic migraine.
Migraine and asthma are comorbid chronic disorders with episodic attacks thought to involve inflammatory and neurological mechanisms.
Researchers have assessed the influence of asthma on the clinical course of episodic migraine.
To be eligible for this observational cohort study, American Migraine Prevalence and Prevention ( AMPP ) study participants had to meet criteria for episodic migraine in 2008, complete the validated six-item asthma questionnaire from the European Community Respiratory Health Survey ( ECRHS ) in 2008, and provide follow-up data in 2009.
Using the ECRHS, researchers defined asthma as a binary variable ( present or absent ) based on an empirical cut score and developed a Respiratory Symptom Severity Score ( RSSS ) based on the number of positive responses ( no severity = 0 positive responses, low severity = 1-2 positive responses, moderate severity = 3-4 positive responses, high severity = 5-6 positive responses ).
Chronic migraine was the primary outcome measure and was defined as those with greater than or equal to 15 headache days per month on the 2009 AMPP Study survey.
The eligible sample for this study included 4446 individuals with episodic migraine in 2008 of whom 17% had asthma. This group had a mean age of 50.4 and was 80.8% female.
In 2009, new onset chronic migraine developed in 2.9% ( 131/4446 ) of the 2008 episodic migraine cohort, including 5.4% ( 40/746 ) of the asthma subgroup and 2.5% ( 91/3700 ) of the non-asthma subgroup.
In comparison to those without asthma, the adjusted odds for individuals with asthma and episodic migraine in 2008 to develop chronic migraine in 2009 were greater than two ( adjusted odds ratio [ aOR ] 2.1; 95% CI: 1.4-3.1 ).
Using the RSSS, the aOR for chronic migraine onset increased with the number of asthma symptoms, but only those in the high RSSS category showed a statistically significant increase in the odds of chronic migraine onset in comparison with the no RSSS reference group ( aOR 3.3; 95% CI 1.7-6.2 ).
In conclusion, asthma is associated with an increased risk of new onset chronic migraine 1 year later among individuals with episodic migraine, with the highest risk being among those with the greatest number of respiratory symptoms.
The exact mechanisms underlying this association are unknown, but could suggest mast cell degranulation, autonomic dysfunction, or shared genetic or environmental factors. ( Xagena )
Martin VT et al, Headache: The Journal of Head and Face Pain, 2015