(527) Determinants of Follow-Up Participation in a Longitudinal Study of Sexual Dysfunction in Multiple Sclerosis

Introduction Sexual dysfunction is a prevalent but often neglected symptom of multiple sclerosis (MS). Sexual dysfunction (SD) in MS patients can be categorized into primary, secondary, and tertiary. While longitudinal studies using tools such as the Multiple Sclerosis Intimacy and Sexuality Questionnaire-19 (MSISQ-19) provide valuable insights, high dropout rates may bias results. Understanding which patients remain engaged versus those who withdraw can help improve recruitment strategies and tailor sexological interventions to diverse patient needs. Objective To identify demographic, clinical, and psychosocial factors associated with follow-up participation in a longitudinal MSISQ-19 study, and to highlight which subgroups may require alternative strategies to sustain engagement. Methods A total of 164 adults with MS (117 females; mean age 39.6 ± 10.9; mean Expanded Disability Status Scale [EDSS] score 2.17 ± 1.27) completed baseline questionnaires assessing demographics, disease characteristics and sexual functioning (MSISQ-19). After 6–12 months, participants were re-contacted; 50.6% completed the follow-up. Comparisons between responders (follow-up) and non-responders (dropouts) were performed using the Mann–Whitney U test for non-normally distributed continuous variables, the t-test for normally distributed ones, and the Chi-square test for categorical data. Results Responders demonstrated significantly lower baseline sexual dysfunction (MSISQ-19 total score, p < 0.05) and lower secondary dysfunction subscale scores (p > 0.05), indicating fewer MS-related symptoms affecting sexual activity. Socio-demographic factors also showed clear associations: patients with higher education (p < 0.01) and active employment (p < 0.05) were substantially more likely to complete the second phase. The difference in age between responders and dropouts was not statistically significant (p = 0.052), although a minor trend toward younger age among responders was observed. Follow-up responders did not differ significantly from dropouts in disease duration or disability level. No significant differences were observed regarding marital status, living arrangement, or place of residence (city/countryside). Conclusions The findings indicate that patients with greater disability, lower education, and lack of employment are less likely to remain engaged in follow-up. To better reach these under-represented subgroups, alternative engagement strategies-such as assisted questionnaire completion, telehealth follow-ups, or integration of sexual health assessment into routine neurological visits-are recommended to ensure that the full spectrum of sexual health needs in MS is represented. Disclosure No