According to study results published in Headache, a majority of patients with chronic migraine receiving onabotulinumtoxinA experience the phenomenon of wear off: Clinicians may consider increasing the units of injected onabotulinumtoxinA to alleviate this burden.

The investigators of this single-center retrospective study evaluated the prevalence, associated factors, and treatment characteristics of onabotulinumtoxinA wear off in patients with chronic migraine.

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The study included 143 patients with chronic migraine treated at the Montefiore Headache Center in the Bronx, New York, with at least 2 documented onabotulinumtoxinA treatments between 2015 and 2017. Patients were assessed for demographic variables, comorbidities, medication overuse, migraine characteristics, dates of onabotulinumtoxinA administration, units of onabotulinumtoxinA administered on each date, training level of physician injector (attending or fellow/resident), treatment response, and type of bridge treatment if wear off was experienced. The presence of wear off was considered if there was a quantitative increase in headache days or if there was increased use of abortive medications, bridging therapies, and emergency department visits/hospitalizations in the 6 weeks leading up to the patient’s next onabotulinumtoxinA session.

OnabotulinumtoxinA wear off occurred in 62.9% of the sample. Between the wear off (n=90) and no wear off (n=53) groups, there was no significant difference in baseline characteristics including mean age at first injection, sex, menstruation-related migraine, medication overuse, and psychiatric comorbidity. Similarly, there was little difference in the injector training level and mean days between injections reported between groups. The total number of treatment sessions was significantly greater in the wear off group vs the no wear off group (7.3 ± 2.5 vs 6.1 ± 2.5; P =.005). Calculated until the first documented wear off, the mean onabotulinumtoxinA units injected in each session were significantly less in the wear off group vs the no wear off group (166.0 ± 13.1 vs 173.4 ± 10.3; P =.0005). OnabotulinumtoxinA wear off was commonly documented 2 to 4 weeks before the patient’s next scheduled injection (in 43.3% of the wear off group), and wear off often occurred after the first injection session (in 40.0% of the wear off group). The most popular bridge therapies used in the wear off period were intramuscular ketorolac injections (33.3%), peripheral nerve blocks (25.6%), and intravenous/oral steroids (7.78%).

Limitations to the study included the potential for patients underreporting wear off if not directly asked; conversely, the rate of wear off could have been overreported if clinicians counseled patients on the potential of wear off occurring. Furthermore, there may have been other factors that could have affected a patient’s subjective experience of wear off.

The investigators indicate that almost two-thirds of patients with chronic migraine who receive onabotulinumtoxinA injections experience the phenomenon of wear off; clinicians may consider increasing onabotulinumtoxinA units to alleviate wear off and to reduce the need for bridging therapies (shorter injection intervals are not recommended).

Reference          

Masters-Israilov A, Robbins MS. OnabotulinumtoxinA wear-off phenomenon in the treatment of chronic migraine [published online September 16, 2019]. Headache. doi: 10.1111/head.13638