Page 60 - The clinical aspects and management of chronic migraine Judith Anne Pijpers

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Chapter 3
Discussion
Being the first controlled follow-up study, this study shows that support of a headache nurse during simple withdrawal therapy increases the chance that a patient with Medication Overuse Headache (MOH) successfully withdraws from overused medication. In this manner, the high drop-out percentage seen in outpatient withdrawal therapy can be reduced.7 As expected, the reduction in headache days during withdrawal therapy is independent of the support of a headache nurse, as this is more likely to be influenced by intrinsic, patient related factors. The current study shows that patients with migraine as the solely underlying headache disorder have a higher chance at response to withdrawal therapy.
The strengths of this study include the controlled design in a large, representative study population of MOH patients. Although randomisation was not achievable, the retrospective design is particularly suited to determine the effect of the headache nurse, since we studied the insulated effect of the nurse and there were no ethical issues or risk of blinding failure. We changed our treatment protocol of patients with MOH during our inclusion period by the employment of a headache nurse in April 2008, but no other changes regarding to treatment protocol or referral strategies were introduced. In a prospective controlled study, the recruitment procedure would lead to a highly motivated population, and it would be extremely difficult to blind patients for receiving or not receiving support by a nurse, since patients must be informed about the nature of a study. One group of patients would thus be instructed not to contact the outpatient clinic at any moment, whilst they know about the availability of support to the other group. This will definitely introduce disappointment and other expectations and will bias the results in favour of the intervention. The results of our retrospective study are not influenced by this kind of bias.
There are also some limitations of our study design. Firstly and most importantly, there was no ability to collect data of patients who did not return for a second visit and were, therefore, stated as lost to follow-up. Since patients were explicitly instructed that they were not allowed to revisit in case of unsuccessful withdrawal, and they were informed that no additional treatment would be supplied, we consider the majority of the lost to follow up patients as unsuccessfully withdrawn. We believe the possibility that loss to follow-up is caused by economic reasons negligible due to the health care system in our country, and