Earlier disability of the patients followed in Multiple Sclerosis centers compared to outpatients

Abstract

Objective The currently published works regarding the multiple sclerosis (MS) natural history report data were collected most often on population of patients recruited in MS centers. The aim was to compare the natural history of a population of patients followed in a MS centre (MSC) with patients followed outside a MS centre (NMSC). Methods Cases were identified through the LORSEP cohort, a network of neurologists (private ambulatory practice, hospitals, and MS centers) in France. Results A total of 3602 patients had been analyzed: 1036 MSC patients and 2566 NMSC patients. No difference was observed regarding gender and initial symptoms. Conversely, MSC patients were younger at MS onset and were more likely to have a primary progressive initial form. Median times (years) to the EDSS scores of 3, 4, and 6 were 5.8 (5.0–6.8), 8.4 (7.9–9.0), 16.0 (14.8–18.1) in the MSC group, respectively, whereas corresponding times were 8.4 (7.9–9.0), 12.3 (11.4–13.4), 19.1 (18.0–20.2) in the NMSC group. These differences according to the type of MS supervision were statistically significant for EDSS3 ( P < 0.0001), EDSS4 ( P < 0.0001), and EDSS6 ( P = 0.01), respectively. These findings were confirmed in Cox multivariate models. Conclusions The patients followed in a MS centre had earlier disability than patients managed otherwise. Analyses exclusively conducted in patients with MS supervised in specialized centers may falsely misestimate the times needed to reach major disability landmarks. Before using registries to study the natural history of MS, efforts should be performed to verify in how far data are exhaustive and to understand the local health care system.