The Association of Timing of Disease-Modifying Drug Initiation and Relapse in Patients with Multiple Sclerosis Using Electronic Health Records

Objective: A large, US de-identified electronic health record (EHR) database (Optum-Humedica de-identified Electronic Health Record dataset) was used to evaluate whether earlier disease-modifying drug (DMD) treatment initiation was associated with improved outcomes in multiple sclerosis (MS).Methods: Newly diagnosed patients from 1 January 2008 to 30 August 2014 (International Classification of Diseases, Ninth Revision, Clinical Modification code: 340. xx; first MS diagnosis = index date) with healthcare activity 1 year pre- and 2 years post-index, and who initiated DMD treatment during the 2 year follow-up period, were included. Patients were categorized as Early or Late Initiators (initiated DMD treatment <= 90 or > 90 days following index, respectively). Relapse was determined by the presence of an MS-related hospitalization or an outpatient encounter with MS diagnosis and corticosteroid prescription within 7 days.Results: A total of 4732 patients met the inclusion criteria: 2042 (43.2%) were Early Initiators and 2690 (56.8%) were Late Initiators. Similar baseline mean age (46.9 years for both cohorts) and Charlson Comorbidity Index scores (Early Initiators: 0.3, Late Initiators: 0.32) were observed. Average time to treatment was 20.9 +/- 27.6 days for Early Initiators and 346.3 +/- 181.1 days for Late Initiators. A significantly higher proportion of Late Initiators (n = 609; 22.6%) had a relapse during the 2 years following MS diagnosis compared with Early Initiators (n = 403; 19.7%; p = .0158). After controlling for covariates using multivariable logistic regression, late initiation of DMD treatment was associated with greater likelihood of relapse compared with early initiation (odds ratio 1.189; 95% CI: 1.031-1.371; p = .0172).Conclusions: Later initiation of DMD treatment (i.e. > 90 days after MS diagnosis) in patients with MS was associated with a greater likelihood of relapse compared with earlier initiation. Early initiation of DMD treatment following a diagnosis of MS may have an effect on long-term outcomes.