Incidence of multiple sclerosis in UK general practice; Risk of infections and mortality.

Multiple sclerosis (MS) is a leading cause of severe neurological disability and is associated with substantial comorbidity. Infections represent a major complication, and patients with MS have an increased risk of mortality. This population-based descriptive cohort study examined the natural history of MS in general practice, focusing on incidence, comorbidities, infection risk, and mortality. Patients with incident MS between 2000 and 2016 were identified from the Clinical Practice Research Datalink (CPRD) and compared with a matched cohort from the general population. Incidence rates, associated risk factors, and subsequent risks of infection and mortality were assessed. The incidence rate of MS was 8.84 cases per 100,000 person-years (95% confidence interval: 8.63-9.06), with higher rates observed in females and individuals aged 30-49 years. Comorbidities and prior infections were significantly associated with an MS diagnosis. Patients with MS had an increased risk of developing infections, particularly central nervous system infections (hazard ratio: 3.43; 95% confidence interval: 1.90-6.19). Mortality rate among patients with MS was nearly twice that of the general population. Male sex, smoking, and being underweight were associated with an elevated risk of mortality, while respiratory diseases and infections were the most common causes of death. These findings, derived from routine general practice data, provide valuable insights for clinicians managing patients with MS. They highlight the increased susceptibility of patients with MS to infections and their elevated mortality risk. Furthermore, they identify modifiable risk factors, such as smoking and comorbidities, that may be targeted to improve patient outcomes.