Mortality trends for multiple sclerosis patients in Sweden from 1968 to 2012

Objective: To assess trends in mortality and causes of death for patients with multiple sclerosis (MS) relative to those without MS in Sweden. Methods: Patients with an MS diagnosis in Sweden between 1964 and 2012 were identified with the Patient Register and the Multiple Sclerosis Register. For this cohort study, each patient with MS (n = 29,617) was matched with 10 individuals without MS (n = 296,164) on sex, year of birth, vital status, and region of residence at the time of MS diagnosis with the Total Population Register. The Causes of Death Register was used to identify causes of death. Cox proportional hazard models were constructed to assess whether risk of mortality was increased for patients with MS. Results: The hazard ratio (HR) for patients with MS was 2.92 (95% confidence interval [CI] 2.86-2.99) for all-cause mortality over the entire study period. The largest differences between the cohorts were death resulting from respiratory (HR 5.07, 95% CI 4.87-5.26) and infectious (HR 4.07, 95% CI 3.70-4.47) diseases. Overall and for each specific cause, there have been improvements for the MS group and a subsequent reduction in the HR. The HR decreased from 6.52 (95% CI 5.79-7.34) for the period of 1968 to 1980 to 2.08 (95% CI 1.95-2.22) for the time period of 2001 to 2012. An interaction between time period and MS exposure showed that the decrease in mortality over time was statistically significant, with a larger decrease for patients with MS than their matched comparators. Conclusions: There has been a substantial improvement in mortality overall and for each specified cause of death for patients with MS compared with individuals without MS; however, large differences still remain.