Clinical Features and Treatment Outcomes of Medication Overuse Headache in Older Patients: Insights from a Nationwide Prospective Registry

<b>Background and Objectives:</b> Medication overuse headache (MOH) presents unique clinical challenges in older adults due to age-related changes and comorbidities. However, data on MOH characteristics and treatment responses in this population remain limited. This study investigated the clinical features, treatment patterns, and short-term outcomes of MOH in older patients. <b>Methods:</b> We analyzed data from the RELEASE registry, a nationwide, multicenter prospective cohort of MOH patients in South Korea. Participants were stratified into older (≥65 years) and younger (<65 years) groups. We compared clinical features, treatment patterns, and 3-month outcomes, and identified factors associated with treatment response in the older group. <b>Results:</b> Among 791 patients, 72 (9.1%) were older. Compared to younger patients, older patients reported more monthly headache days (30.0 vs. 27.0, <i>p</i> = 0.012), more days using acute medication (30.0 vs. 20.0, <i>p</i> < 0.001), and fewer headache-free days (0.0 vs. 3.0, <i>p</i> = 0.012). They also experienced more severe headache days (12.5 vs. 10.0, <i>p</i> = 0.056). Despite this, older patients showed lower disability, with significantly lower Migraine Disability Assessment scores (30.0 vs. 46.0, <i>p</i> < 0.001) and a trend toward lower Headache Impact Test-6 scores (64.5 vs. 66.0, <i>p</i> = 0.065). In multivariable analysis, poor adherence to preventive treatment (≤24%) was significantly associated with non-response (OR 0.13, 95% CI: 0.02-0.96, <i>p</i> = 0.045) at 3 months. <b>Conclusions:</b> Older patients with MOH showed distinct clinical features, including higher headache frequency and severity but relatively lower disability. Improving adherence to preventive treatment may enhance treatment response. Age-specific management strategies are needed.