72 Chapter 3 While we propose to use a uniform definition for all patients, it should be noted that the use of different definitions may have different implications for CM, HFEM and LFEM patients. For instance, defining days with triptan intake as a migraine day influences the number of MMD for EM patients in particular. There are several possible explanations for this finding. For example, in our cohort in HFEM and CM patients the number of medication days may be relatively low in relation to the total MMD as compared to EM patients as our patients receive the instruction to prevent MOH.16 Correspondingly, patients with LFEM may have more latitude to take a triptan, since they are less prone for MOH. We hypothesize LFEM patients take their triptan in time, before the attack becomes complete, which results in relatively more days with triptan intake and missing migraine characteristics. Headache duration was the most common missing factor for CM and HFEM, whereas nausea/vomiting or photophobia/phonophobia was most often missing for LFEM. Patients with CM or HFEM might take their medication earlier in an attack, preventing the headache from lasting ≥4 hours, presumably driven by a higher anxiety for upcoming attacks.17-19 We showed that including only days where the headache successfully responds to triptan intake as migraine day, as stated in the clinical guidelines,1, 2 reduces the number of migraine days with 5.2%, equaling a 0.38 average decrease in MMD. However, we argue that the definition for triptan effectiveness has limitations. For example, migraine days with “mild” severity would never be marked as having an effective triptan response, because a triptan is only considered effective according to the clinical guidelines when it reduced a moderate or severe headache to mild or no pain 2 hours post-dose. In clinical practice, patients may already take a triptan when the headache is still mild. Moreover, in most other E-diaries the information on triptan effectiveness is not asked or asked without specifying the severity before and after triptan intake. We therefore propose to include all days with triptan intake independent of effectivity in the definition of a migraine day to avoid heterogeneous outcomes. This study has several major strengths. Firstly, data was collected in a large, well-defined patient cohort over a long follow-up period. Moreover, we used our validated headache E-diary which has been shown to provide reliable migraine data.6 Our study also presents some limitations. Firstly, we did not look in detail at the definition of a migraine day based on aura symptoms, but we do propose to include all days with (visual) aura symptoms lasting 5-60 minutes as migraine days.6 We solely took visual aura symptoms into account, since 98-99% of all migraine attacks
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