Multiple Sclerosis and Risk of Infection-Related Hospitalization and Death in US Veterans

Abstract

Background: This study estimated the risk of infection-related hospitalizations and death in patients with and without multiple sclerosis (MS). Methods: We identified adults with MS in the US Department of Veterans Affairs (VA) system between 1999 and 2010. Each veteran with MS was matched, on age and sex, with up to four veterans without MS. Multivariable Cox proportional hazards regression models were performed to assess the influence of MS on the development of serious and fatal infections. Results: The cohort included 7743 veterans with MS and 30,972 veterans without MS. Mean (SD) age was 53.8 (13.3) years, and 80.8% were male. The incidence per 1000 person-years of overall serious infections was 19.2 (95% confidence interval [CI], 17.6–20.8) for those with MS and 10.3 (95% CI, 9.8–10.9) for those without MS. Fatal infection incidence rates were 1.2 (95% CI, 0.8–1.7) for patients with MS and 0.5 (95% CI, 0.3–0.6) for patients without MS. Regression models showed that veterans with MS were at greater risk for overall serious (hazard ratio [HR] = 1.52, P < .01) and fatal (HR = 1.85, P = .03) infections and serious respiratory (HR = 1.31, P = .01), urinary tract (HR = 4.44, P < .01), and sepsis-related infections (HR = 2.56, P < .01). Conclusions: This study provides evidence that VA patients with MS are more likely than those without MS to be hospitalized and die of infection.