Efficacy of Anti-IL-6 Treatments on Migraine in Patients Treated With Anti-IL-6 for a Rheumatological Condition

In this study, the investigators aim to measure the proportion of patients experiencing a reduction in migraine among those treated with anti-IL-6 therapy for their rheumatological condition, in terms of migraine frequency or intensity (primary objective). The secondary objectives are to : * Measure the proportion of patients experiencing a reduction in migraine among those treated with anti-IL-6 therapy for their rheumatological condition, in terms of (a) frequency, (b) intensity, (c) both frequency and intensity of migraines. * Compare the proportion of patients experiencing a reduction in migraine in terms of frequency or intensity between those treated with anti-IL-6 and a group of patients treated with anti-TNF (tumor necrosis factor) therapy. From a pre-established list compiled by the investigators of patients on anti-IL-6 therapy (anti-IL-6 group) and patients on anti-TNF therapy (control group), all patients will be contacted by phone to identify those with migraine, using the International Classification of Headache Disorders, version 3 (ICHD-3) criteria from the International Headache Society (IHS). In cases where migraine is present, the effect of anti-IL-6 (anti-IL-6 group) or anti-TNF (control group) treatment in terms of the proportion of patients experiencing a reduction in migraine will be assessed using the Patient Global Impression of Change (PGI-C) score: a validated tool, widely used, translated into French and made available by eProvide - Mapi Research Trust \[https://eprovide.mapi-trust.org/instruments/patient-global-impressions-scale-change-improvement-severity#need\_this\_questionnaire\]) (comparison: before vs. during treatment). The episodic or chronic nature of migraine will be determined during the telephone interview according to the following criteria: fewer than 15 monthly headache days for episodic migraine, and at least 15 monthly headache days - of which at least 8 days have migrainous features - for chronic migraine (IHS definition). All patients on this list who meet the inclusion and non-inclusion criteria and agree to participate in the study will be enrolled. The inclusion of a control group - comprising patients treated with a biotherapy other than anti-IL-6, namely anti-TNF agents - will strengthen the level of attribution of the measured effect to anti-IL-6 treatment and help offset recall bias.