Epidemiology of multiple sclerosis: results from a large observational study in the UK

Multiple sclerosis (MS) progression to mortality may not be solely determined by the underlying autoimmune process. We conducted a study in a large cohort of MS patients with the aim of describing characteristics of MS patients and identification of predictors for all-cause mortality in this patient group. We performed a retrospective analysis of primary care data from the UK Clinical Practice Research Datalink. Incident MS cases diagnosed between 1993 and 2006 were identified and validated using electronic and original medical records. Patients were followed to identify deaths; hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional regression with age as time-scale. In total, 1713 incident MS cases were identified. Following MS diagnosis, frequent comorbidities were infections (80%), and depression (46%). Adjusted HRs (95% CIs) for all-cause mortality were: 2.0 (1.2-3.4) for current smoking; 7.6 (3.2-17.7) for alcohol abuse; 2.7 (1.6-4.5) for pneumonia and influenza; 4.1 (2.7-6.3) for urinary tract infections; 2.2 (1.2-4.2) for heart disease and 4.9 (2.9-8.0) for cancer. Our results suggest that MS survival is influenced not only by the underlying autoimmune process, but also by patient comorbidities and lifestyle factors.