Mapping the risk of infections in patients with multiple sclerosis: A multi-database study in the United Kingdom Clinical Practice Research Datalink GOLD and Aurum.

BACKGROUND

People with multiple sclerosis (pwMS) have an increased risk of infections; risk factors include underlying disease, physical impairment and use of some disease-modifying treatments.

OBJECTIVE

To quantify changes in population-level infection rates among pwMS and compare these to the general population and people with rheumatoid arthritis (pwRA), and identify patient characteristics predictive of infections after MS diagnosis.

METHODS

We conducted a multi-database study using data on 23,226 people with MS diagnosis from the UK Clinical Practice Research Datalink Aurum and GOLD (January 2000-December 2020). PwMS were matched to MS-free controls and pwRA. We calculated infection rates, and estimated incidence rate ratios (IRR) and 95% confidence intervals (CI) of predictors for infections ⩽ 5 years after MS diagnosis using Poisson regression.

RESULTS

Among pwMS, overall infection rates remained stable - 1.51-fold (1.49-1.52) that in MS-free controls and 0.87-fold (0.86-0.88) that in pwRA - although urinary tract infection rate per 1000 person-years increased from 98.7 (96.1-101) (2000-2010) to 136 (134-138) (2011-2020). Recent infection before MS diagnosis was most predictive of infections (1 infection: IRR 1.92 (1.86-1.97); ⩾2 infections: IRR 3.00 (2.89-3.10)).

CONCLUSION

The population-level elevated risk of infection among pwMS has remained stable despite the introduction of disease-modifying treatments.