PRM35 - Comparing Different Data on Disease Burden In Multiple Sclerosis

Abstract

Numerous studies exist on costs of multiple sclerosis (MS). Comparison of results, even with similar study methods, is challenging due to differences in the samples. We investigate methods for explaining and adjusting for differences between samples and results using two large cross-sectional data sets. In two methodologically very similar European cost-of-illness studies in MS, conducted in 2005 and 2015, patients had provided data on their disease, resource use, work productivity and health-related quality of life. Since disease severity was the strongest driver of costs (and utilities), we compared resource use for patients with mild MS only (Expanded Disability Status Scale 0-3), including 8351 patients from 6 countries. Patients in the 2015 study were older (2.8 years) and had longer disease duration (1.7 years). Employment rate in those below 65 years was lower (64% vs. 72%), possibly due to higher age and changes in economic conditions. The 3-month relapse rate was 32% lower, potentially a consequence of higher use of disease-modifying treatments (DMTs; 70% in 2015 vs. 57% in 2005), but also due to a sample with possibly more benign disease. The lower relapse rate might also have contributed to a lower rate of short-term sick leave (19% vs. 24%), hospitalisations (4% vs. 7%) and use of services (7% vs. 14%). However, these changes may also be a consequence of trends unrelated to MS such as more control on sick leaves, fewer inpatient admissions, and less service provision. When comparing patient samples and results in MS, it is not sufficient to control for disease severity alone. Additional factors need to be adjusted for to allow for appropriate comparisons of disease burden, including demographics, disease duration and disease course, as well as external factors such as changes in economic conditions and healthcare systems.