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Expert commentary

by Thomas N. Ward, MD

The Chronic Migraine Epidemiology and Outcomes (CaMEO) study is a web-based cross-sectional and longitudinal study designed to evaluate episodic migraine (EM, < 15 days per month) and chronic migraine (CM, ≥15 headache days per month with at least 8 meeting criteria for migraine). Adults 26-57 years of age meeting modified International Classification of Headache Disorders, 3rd edition (ICHD-III) were included (n=16,789). In this study, EM was further divided into the categories of low- frequency EM (1-9 monthly headache days (MHDs)), high-frequency episodic migraine (HFEM, 10-14 MHDs), low- frequency chronic migraine (LFCM, 15-23 MHDs) and high-frequency chronic migraine (HFCM, 24 or more MHDs). In this adult study, 13,473 had LFEM, 1840 had HFEM, 1035 had LFCM and 441 had HFCM.

Severe disability (Migraine Disability Assessment Scale (MIDAS) grade IV), was present in 12.8% of LFEM, 51.9% of HFEM, 66.3% of LFCM and 70.1% of HFCM. The Migraine Interictal Burden Scale (MIBS) with severe scores ≥5 similarly showed scores of 19.2%, 38.2%, 46.7% and 58.3% respectively. Interestingly, moderate MIBS scores of 3-4 were also similar in the HFEM (17.9%) and LFCM (17.0%) groups. Depression, as assessed by the PHQ-9 with scores ≥10, was 27.6% (LFEM), 47.3% (HFEM), 54.9% (LFCM), and 60.8% (HFCM). Anxiety with scores ≥10 on the GAD-7 was present in 41.9% of HFEM compared to 46.9% of LFCM. Allodynia was present in 57.5% of the HFEM group and 61.7% of LFCM.

HFEM and LFCM were also similar with regard to healthcare utilization. 32.3% of HFEM were managed by a healthcare professional; for LFCM it was 36.5%. 8% of HFEM were seeing a specialist compared to 11.9% for LFCM. 10.2% of HFEM had gone to an emergency room for headache treatment in the past 6 months, for LFCM it was 10.3%.

These findings show similar amounts of disease burden, affective disorders, allodynia and healthcare utilization for HFEM and LFCM. While some potential biomarkers may suggest distinctions between EM and CM (CGRP levels and neuroimaging) this study suggests we may consider the range of headache frequency more as a continuum with many similarities between HFEM and LFCM. Clearly, effective measures to reduce headache frequency are important.

 

References

  1. 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
  2. Schwedt TJ, Chong CD, Wu T et al. Accurate Classification of Chronic Migraine via Brain Magnetic Resonance Imaging. Headache 2015; 55(6): 762-777.
  3. Cernuda-Morollón E, Martinez-Camblor P, Ramón C et al. CGRP and VIP Levels as Predictors of Onabotulinumtoxin Type A in Chronic Migraine. Headache 2014; 54(6): 987-995.
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