Heterogeneity of sickness absence and disability pension trajectories among individuals with MS.

BACKGROUND

The variability of progression of multiple sclerosis (MS) suggests that MS is a heterogeneous entity.

OBJECTIVE

The objective of this article is to determine whether sickness absence (SA) and disability pension (DP) could be used to identify groups of patients with different progression courses.

METHODS

We analyzed mean-annual net months of SA/DP, five years prior to MS diagnosis, until the year of diagnosis, and five years after for 3543 individuals diagnosed 2003-2006, by modeling trajectory subgroups.

RESULTS

Five different groups were identified, revealing substantial heterogeneity among MS patients. Before diagnosis, 74% had a flat trajectory, while the remaining had a sharply increasing degree of SA/DP. After diagnosis, 95% had a flat or marginally increasing trajectory, although at various SA/disability pension (DP) levels, whereas a small group of 5% had decreasing SA/DP. A majority had few or no SA/DP months throughout the 11-year study period. Higher age and a lower educational level were associated with an unfavorable trajectory ( values <0.01).

CONCLUSIONS

There's a considerable heterogeneity of MS progression in terms of SA/DP. Compared with other measures of disability, sickness-absence and disability pension offer a continuous variable that can be assigned to every individual for each time period without missing data. To what extent the SA/DP measure reflects classical MS outcome-measures as well as how correlated it is with co-morbidities and working-conditions needs to be investigated further.