Page 141 - The clinical aspects and management of chronic migraine Judith Anne Pijpers

In conclusion, the efficacy of BTA is at best modest, but taking into account the low risks of adverse events, and the severity of chronic migraine without many other therapeutic options, BTA can be considered for patients with chronic migraine, without medication overuse, who failed on previous preventatives (either due to adverse events of lack of efficacy). As indicated by the discussion on whether or not 17.5 units could be as effective as 155 units of BTA, studies on dose-response curves are warranted. Since BTA is not effective in episodic migraine,57 therapy should be ceased when patients are reverted from chronic to episodic migraine.
A new subclass of preventative are the antibodies against CGRP or its receptor (further referred to as CGRP-antibodies).68 Several trials have been performed in chronic migraine, but direct comparison with our trial described in chapter 4 and previous BTA-trials is hampered due to differences in design and selection of patients. However, with these limitations in mind, the anti-CGRP treatment groups in these trials seem to yield similar reduction in migraine or headache days per month as the placebo group (withdrawal therapy only) described in chapter 4. The withdrawal therapy only group in chapter 4 had a mean reduction of 4.4 headache days and 7.0 migraine days per month. The mean reduction of the CGRP-antibody treatment groups were 4.6 monthly headache days for Fremanezumab (baseline headache days 12.8)69, 6.6 monthly migraine days for Erenumab (baseline migraine days 17.9)70 and 4.8 monthly migraine days for Galcanezumab (baseline migraine days 19.2)71. The mean additional therapeutic gain versus placebo was 11-17%.69–71
Whilst the mean therapeutic gain is still moderate, the potential benefit of the CGRP-antibodies has been suggested to be in a large treatment effect in a subgroup of patients, called responders (at least 50% reduction in headache or migraine days) or even super responders (75-100% reduction in headache or migraine days).72 The odds for response in the chronic migraine trials is approximately 2 - 2.5 times higher for the treatment group versus placebo.69–71 Considering the high costs of CGRP-antibodies, defining predictors for response is very important. As for withdrawal therapy (chapter 6), cephalic and extracephalic cutaneous allodynia might be a relevant predictor.
Furthermore, a comparison or added value of this preventive medication to standard care (withdrawal of medication) has not been studied. Hence it is still unknown whether medication overuse should be treated first by withdrawal
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Summary and general discussion
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