Objective:

To examine adherence to calcitonin gene–related peptide monoclonal antibody (CGRP mAb) treatment among patients who initiated onabotulinumtoxinA (OnabotA) and subsequently added on or switched to a CGRP mAb.

Background:

The 2021 American Headache Society consensus statement and emerging clinical reports suggest that the combination of a CGRP mAb and OnabotA in patients with migraine is probably effective. However, real-world utilization of combination treatments relative to monotherapies among patients with chronic migraine (CM) has not been examined previously.

Design/Methods:

In this retrospective cohort study, adult patients with CM (ICD-10-CM G43.7X) treated with OnabotA and subsequently with a CGRP mAb were identified from IBM MarketScan® claims databases (05/17/2018 – 06/30/2021). The index date was the first CGRP mAb prescription. Patients were categorized into two cohorts: “addition” (concomitant OnabotA and index CGRP mAb usage ≥28 days) and “switch” (otherwise). Adherence (≥80% of days covered on medication) over a 6-month follow-up period was assessed using logistic regression to adjust for baseline characteristics during the 6-month pre-index period.

Results:

The study sample included 610 patients in the addition cohort and 680 in the switch cohort. Lower adherence to index CGRP mAb was observed in the addition versus switch cohorts (38.9% vs 48.2%; P<0.001). After controlling for baseline characteristics, the switch cohort had 41% (95% CI: 1.12–1.77; P=0.003) higher odds of adherence versus the addition cohort. In the addition cohort, 60.2% (n=367) of patients were adherent to OnabotA alone or in combination with a CGRP mAb, and 19.3% (n=118) were adherent to combination use of the index CGRP mAb and OnabotA.

Conclusions:

During follow-up, patients who added a CGRP mAb to OnabotA had significantly lower adherence to the CGRP mAb versus patients who switched to a CGRP mAb. These findings suggest that usage of CGRP mAb as add-on to OnabotA occurs for a limited duration.