Abstract
BACKGROUND: Most patients treated with erenumab in clinical practice have chronic migraine (CM). We assessed the rate and possible predictors of conversion from CM to episodic migraine (EM) in a real-life study. MAIN BODY: We performed a subgroup analysis of patients treated with erenumab from January 2019 to February 2020 in the Abruzzo region, central Italy. Treatment was provided according to current clinical practice. For the purpose of the present study, we included patients fulfilling the definition of CM for the three months preceding erenumab treatment and with at least 6 months of follow-up after treatment. We assessed the rate of conversion to EM from baseline to Months 4-6 of treatment and during each month of treatment. To test the clinical validity of conversion to EM, we also assessed the decrease in monthly headache days (MHDs), acute medication days, and median headache intensity on a Numerical Rating Scale (NRS). We included in our study 91 patients with CM. At Months 4-6, 62 patients (68.1%) converted from CM to EM; the proportion of converters increased from Month 1 to Month 5. In the overall group of patients, median MHDs decreased from 26.5 (IQR 20-30) to 7.5 (IQR 5-16; P < 0.001) compared with baseline, while median acute medication days decreased from 21 (IQR 16-30) to 6 (IQR 3-10; P < 0.001) and median NRS scores decreased from 8 (IQR 7-9) to 6 (IQR 4-7; P < 0.001). Significant decreases were found both in converters and in non-converters. We found no significant predictors of conversion to EM among the patients' baseline characteristics. CONCLUSIONS: In our study, two thirds of patients with CM converted to EM during 6 months of treatment with erenumab. MHDs, acute medication use, and headache intensity decreased regardless of conversion from CM to EM.