To determine a threshold number of monthly headache days (MHDs) that clinicians can use as a therapeutic goal for patients with chronic migraine (CM).

Current therapeutic goals for migraine treatment include ≥50% or ≥75% reduction in monthly migraine days (ie, responder rates). MHDs may be a more straightforward assessment tool for treatment of patients with CM.

In PROMISE-2 (NCT02974153), a randomized, double-blind study evaluating eptinezumab for the preventive treatment of CM, patients (N=1072) received eptinezumab 100mg, 300mg, or placebo on Day 0 and Week 12; all arms were pooled for analysis. Available data for 6-item Headache Impact Test (HIT-6) total score, Patient Global Impression of Change (PGIC), and days of acute medication use were combined for Weeks 4, 12, 16, and 24 and analyzed by number of MHDs (≤4, 5-9, 10-14, ≥15) during the 4 weeks preceding the respective assessment. Patient-months correspond to 4-week study intervals.

Of patient-months with ≤4 MHDs, 67.6% (561/830) were associated with “little to none” or “some” HIT-6 impairment, vs 47.6% (447/940), 29.9% (240/803), and 13.9% (210/1507) of patient-months with 5-9, 10-14, and ≥15 MHDs, respectively. Of patient-months with ≤4 MHDs, 85.8% (1079/1258) were associated with “very much” or “much” improved PGIC, vs 69.9% (989/1415), 49.6% (607/1224), and 21.5% (480/2229) of patient-months with 5-9, 10-14, and ≥15 MHDs, respectively. Patient-months with ≤4, 5-9, 10-14, and ≥16 MHDs used acute medication for ≥10 days on 1.9% (21/1111), 5.0% (63/1267), 49.6% (670/1351), and 74.1% (1232/1662) of patient-months, respectively.

In this post hoc analysis, patients improving to ≤4 MHDs achieved superior outcomes with the least acute medication use, suggesting that 4 MHDs may be a useful treatment goal for patients with CM.