The influence of age at disease onset on future relapses and disability progression in multiple sclerosis patients on immunomodulatory treatment

OBJECTIVE: To investigate the relation of age at disease onset and clinical outcomes across the life-span from adolescence in multiple sclerosis (MS) patients on disease-modifying therapy (DMT). METHODS: We analysed data from the Swiss association for joint tasks of health insurers database containing data from 14,718 MS patients. Patients were included in this analysis when they were on DMT for at least one year. The influence of age at disease onset on future relapses and disability worsening was explored with multivariable Cox proportional hazard regression models. RESULTS: Data from 9,705 MS patients was analysed. Pediatric-onset patients (n=236) had higher relapse rates and marginally slower disability worsening rates compared with adult-onset MS patients (n=9,469). The risk for relapses was highest in childhood and decreased continuously to about 35 years of age. It remained stable for about a decade and then again continuously decreased. In contrast, disability worsening hazards remained stable from childhood to about 32 years of age and then increased sharply around the age of 45 years. CONCLUSIONS: Age is an important factor affecting clinical outcomes in MS. This should be considered when designing clinical trials or choosing DMT.