Causes of death in patients with multiple sclerosis and matched referent subjects: a population-based cohort study

Background and purpose: Multiple sclerosis (MS) has been associated with increased mortality rates. However, influence of lifestyle parameters remains unknown, and inconsistencies exist regarding findings for causes of death. Methods: We conducted a population-based cohort study using the General Practice Research Database, Hospital Episode Statistics, and national death certificates (January 2001 through March 2008). To each patient with MS (n = 1270), up to six referent subjects without MS were matched by age, gender, and practice. Cox proportional hazards models were used to estimate mortality rate ratios (HRs). Results: Patients with MS had a 3.5-fold increased mortality rate for all-cause mortality, compared with referent subjects (HR 3.51, 95% CI 2.634.69). The rate further increased amongst current smokers (HR 6.72, 95% CI 4.1610.87) (but not in ex-smokers) and subjects with a body mass index of