Observational Studies: Persistence
Four open-label studies were identified that evaluated topiramate21-
23 or amitriptyline alone,24 while 2 comparative studies
evaluated divalproex and topiramate,25 and flunarizine
and propranolol.26 Studies were conducted in Germany,21-23
Austria,24 Belgium,26 the Netherlands,27 and Brazil.25 Dosages
varied by individual patient but were within the range of
approved FDA-labeled dose for migraine prophylaxis, where
applicable. Persistence was also evaluated in 2 large claims
database analyses that included a wide range of medications
from the 3 major classes of oral migraine prophylaxis, without
regard for dose.27,28 These studies report that persistence ranged
from 41% to 88% at 2 months, 19% to 79% at 6 months, and
7% to 55% at 12 months. Individual study data are shown in
Table 1.