Patients managed with onabotulinumtoxinA (Botox) for their chronic migraine can experience a wear-off in effect before the next scheduled treatment, an international study has found.
The retrospective chart review of 112 patients from treatment centres in six countries including Australia found overall headache days significantly increased in weeks 12 and 13 after injection compared to weeks 5-8 which were considered to represent maximal effect.
Similarly, moderate to severe headache days also increased by week 13 and days with use of acute headache medication also increased in weeks 12 and 13.
Half (51%) of the group experienced a ≥30% wear-off of response to treatment in weeks 12/13 but 25% of the group experienced an early wear-off in effect by weeks 10/11.
The study found factors such as gender, age, headache duration, headache days per month before OnabotA treatment, OnabotA dose or cycle number, the treating headache centre, or concomitant use of oral migraine prophylaxis did not appear to influence wear-off.
“The present data demonstrate that, at least within the first 4 treatment cycles, 13 weeks intervals are not sufficient to maintain a continuing response to OnabotA treatment in many patients, and that an important number of patients show wear‐off even earlier, starting at 10 weeks,” the researchers wrote in Headache.
“This wear‐off phenomenon may negatively affect quality of life of chronic migraine patients under OnabotA treatment,” the study authors concluded.
They noted that the findings were consistent with those of a number of other studies and further research was needed to find strategies to counteract OnabotA wear‐off during a treatment cycle.
Australian investigator on the study Dr Catherine Stark from the Austin Hospital told the limbic the findings confirmed clinical observations that a reasonable proportion of patients do start to experience wear-off around week 11.