Author Of 1 Presentation
P1010 - Comparison of Models for Disability Accumulation on the Expanded Disability Status Scale in Multiple Sclerosis (ID 1665)
When assessing long-term trends in disability accumulation and economic models to compare treatments in multiple sclerosis (MS), disability accumulation on the Expanded Disability Status Scale (EDSS) is commonly assumed to depend only on the present state of the patient. Such models also often assume that the probability of disability accumulation is constant over the disease course.
The objective of this study was to assess the assumptions of models used to describe disability accumulation within patients with MS.
Patients enrolled in the Comprehensive Longitudinal Investigation of Multiple Sclerosis at Brigham and Women’s Hospital (CLIMB) who had ≥6 consecutive clinic visits, which occurred every 6 months, were included in this analysis. This yielded 7257 observations for 1039 patients. To assess whether a previous EDSS score only was sufficient for modeling disability accumulation, we compared 2 models for EDSS transitions with the EDSS scale grouped into 3 score levels (0–1.5, 2–3.5, ≥4) using a likelihood ratio test. The first transition model included only the present EDSS score, and the second model included the present and the previous EDSS scores. In addition, we fit a repeated measures proportional odds model with 1, 2, and 3 previous EDSS scores to assess if additional previous EDSS scores added to the model. To determine if the probability of disability accumulation changed with time, we assessed whether disease duration <15 years or ≥15 years was associated with a change in the transition matrix using a likelihood ratio test. Finally, we fit the repeated measures proportional odds model to assess if disease duration improved the model that included 3 previous EDSS scores.
When the model with only the present EDSS score was compared with the model with 2 previous EDSS scores, the model including the 2 previous EDSS scores led to a better model fit (P<0.001). Further, all previous EDSS scores were associated with subsequent EDSS score in the repeated measures proportional odds model (1 previous EDSS, OR [95% CI]: 4.64 [4.31–4.99]; 2 previous EDSS, OR [95% CI]: 1.77 [1.65–1.90]; 3 previous EDSS, OR [95% CI]: 1.63 [1.53–1.73]). Incorporating disease duration also improved model fit using both approaches (P<0.001 for each method).
Additional EDSS history and disease duration may be important to incorporate into disability accumulation modeling for MS.