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

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.

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).

Patients with MS had a 3.5-fold increased mortality rate for all-cause mortality, compared with referent subjects (HR 3.51, 95% CI 2.63-4.69). The rate further increased amongst current smokers (HR 6.72, 95% CI 4.16-10.87) (but not in ex-smokers) and subjects with a body mass index of <20 kg/m(2) (HR 6.67, 95% CI 3.50-12.73). The HR was highest for infectious/respiratory-related deaths (HR 7.69, 95% CI 4.92-12.02) and was significantly increased for deaths related to cardiovascular diseases (2.4-fold) and cancer (1.9-fold), but not for accidents and suicide related deaths.

British patients with MS have a 3.5-fold increased mortality rate compared with the general population. Smoking and respiratory diseases are major (potentially preventable) factors related to increased mortality rate amongst patients with MS.