Disability in chronic migraine with medication overuse: treatment effects through 5 years.

Chronic migraine accompanied by medication overuse is particularly difficult to treat. The number of treatment investigations is limited, few have included follow-up beyond 6 months and almost none has examined whether treatment leads to concurrent improvements in disability and functional impairment. This open-label study addresses these limitations. We have been prospectively following an initial cohort of 84 chronic migraine patients with medication overuse, who at the time of this evaluation had been reduced to 58, for an extended period to assess longer-term maintenance of effects, using measurement procedures identical to those in the original investigation. Thus, the specific aim was to determine the clinical status, with respect to pain indices and disability level, of chronic migraine patients with medication overuse who were treated and followed prospectively for 5 years. All patients completed a brief inpatient treatment programme, in which they were withdrawn from their offending medications and subsequently placed on more appropriate preventive antimigraine medications. Both end-point, wherein missing data points were estimated, and continuer analyses, wherein data analysis was limited to the 58 individuals with complete datasets, revealed significant improvement on all measures studied-headache days per month, analgesic consumption and Migraine Disability Assessment (MIDAS) total score. The percentage reduction from baseline to 5 years for the MIDAS total score was 76.0%, while the percentage of individuals revealing improvements of clinically significant magnitude (≥ 50%) on the MIDAS was 91.9%. MIDAS total scores were lower at 5 years than at some of the intervening follow-up intervals. Comparisons of those who completed the 5-year follow-up (n = 58) with those who did not revealed no differences at baseline. This finding, coupled with the nearly identical results for the end-point and continuers analyses, suggests that attrition did not have a bearing on outcome. None of the patients completing the 5-year follow-up had relapsed since the prior 3-year follow-up assessment. High levels of maintenance were revealed at 5 years, with disability scores showing some continued improvement over time. The implications of these findings and the limitations of the study are discussed.