Background: Little is known about infection risk in multiple sclerosis (MS).

Objective: We examined infection-related health care utilization in people with and without MS.

Methods: Using population-based health administrative data from British Columbia, Canada, people with MS were followed from their first demyelinating claim (1996-2013) until death, emigration, or study end (2013). Infection-related hospital, physician, and prescription data of MS cases were compared with sex-, age-, and geographically matched controls using adjusted regression models. Sex and age differences (18-39, 40-49, 50-59, 60+ years) were explored.

Results: Relative to 35,837 controls, 7179 MS cases were over twice as likely to be hospitalized for infection (adjusted odds ratio: 2.39; 95% confidence interval (CI): 2.16-2.65), had 41% more physician visits (adjusted rate ratio (aRR): 1.41; 95% CI: 1.36-1.47), and filled 57% more infection-related prescriptions (aRR: 1.57; 95% CI: 1.49-1.65). Utilization was disproportionately higher in MS men than women and was elevated across all ages. MS cases had nearly twice as many physician visits and two to three times more hospitalizations for pneumonia, urinary system infections, and skin infections (aRRs ranged from 1.6 to 3.3) and over twice as many hospitalizations for intestinal infections (aRR = 2.6) and sepsis (aRR = 2.2).

Conclusion: Infection-related health care utilization was increased in people with MS across all age groups, with a higher burden for men.

Keywords: Multiple sclerosis; health care utilization; infections; population-based data.