Diagnosis-specific sickness absence and disability pension before and after multiple sclerosis diagnosis: An 8-year nationwide longitudinal cohort study with matched references.

BACKGROUND

Multiple sclerosis (MS) typically onsets when of working age and may reduce work capacity. Previous studies have examined the risk of sickness absence (SA) and disability pension (DP) among MS patients, however, limited knowledge is available on whether MS patients have an excess risk for SA/DP when compared with the general population in Sweden. Moreover, no information exists on the actual diagnoses for SA and DP among MS patients and whether the patterns of SA/DP diagnoses differs to those without MS. We aimed to explore diagnosis-specific SA and DP among working-aged MS patients both before and after MS diagnosis, in comparison to the levels and distributions of SA and DP diagnoses of a matched reference group and analyze the risk of diagnosis-specific DP.

MATERIALS AND METHODS

Longitudinal Swedish register data of the 2567 MS patients diagnosed with MS in 2009-2012 when aged 25-59 and 10,268 population-based matched references (matched on sex, age, educational level, type of living area, and country of birth) were analysed regarding annual diagnosis-specific SA and DP in the four years before and four years after MS diagnosis. Annual differences in the mean numbers of SA and/or DP net days were calculated with 95% confidence intervals (CI). Hazard ratios (HR) with 95% CI from Cox proportional hazard models were used to compare risks for new all-cause and diagnosis-specific DP after MS diagnosis among the MS patients and references.

RESULTS

The mean SA/DP net days/year increased among MS patients over follow-up, due to both MS and other diagnoses. During follow-up, around 50% of MS patients had some SA/DP compared to 20% of references. The mean days of SA/DP among the MS patients compared to references increased from 10.3 more days (95% CI: 6.6-14.2) four years prior to MS diagnosis to 68.9 days (62.8-75.1) 4 years after MS diagnosis. Although most new DP among MS patients were due to MS, 15% were not. The adjusted HR for all-cause DP was 23.1 (18.1-29.5). MS patients also had higher risks of new DP due to all diagnoses except MS (HR 3.4; 2.4-4.8), musculoskeletal (HR 2.6; 1.1-6.0) and mental (HR 2.0; 1.1-3.6) diagnoses compared with references.

CONCLUSION

MS patients had higher levels of SA/DP days/year than the references, already 4 years before the MS diagnosis, and increasingly so thereafter. The excess of SA/DP prior to MS diagnosis could be related to MS onset. However, the excess of SA/DP days were not all due to MS diagnoses, even after being diagnosed with MS. MS patients had a higher risk of having a new DP after being diagnosed with MS in total, but also for diagnoses other than MS.