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Infection Risk, Medical Claims High Among Patients With Multiple Sclerosis


Patients with multiple sclerosis have high rates of urinary and kidney infections, inpatient hospitalizations, and outpatient hospital claims, according to recent results presented at the Americas Committee for Treatment and Research in Multiple Sclerosis annual meeting.

High rates of urinary and kidney infections, as well as inpatient hospitalization and outpatient hospital claims, were seen among patients with multiple sclerosis (MS) following a retrospective study of commercial insurance records.

The authors presented their abstract showing these results at this year’s virtual annual meeting of the Americas Committee for Treatment and Research in Multiple Sclerosis. Data for January 2010 through June 2019, which they used in their analysis, came from the IQVIA adjudicated claims database and outcomes were compared between patients with MS (n = 87,755) and controls (n = 87,755) matched 1:1 on age, sex, payer type, Census region, and index year. Risks were investigated pertaining to urinary/kidney, pneumonia/influenza, other respiratory/throat, viral, skin, fungal, and opportunistic infections (eg, pneumocystis pneumonia, cytomegaloviral disease, progressive multifocal leukoencephalopathy, toxoplasmosis, etc).

“It is important to understand risk of specific infections in patients with MS,” the authors said. “However, population-based studies in the United States are rare.”

Their analysis revealed elevated outpatient claims among those with MS vs controls for all infections evaluated:

  • Urinary/kidney: 14.23% vs 7.82% (relative risk [RR], 1.82; 95% CI, 1.77-1.87; P < .0001)
  • Pneumonia/influenza: 3.20% vs 2.76% (RR, 1.16; 95% CI, 1.10-1.23; P < .0001)
  • Other respiratory/throat: 30.31% v. 30.05% (RR, 1.01; 95% CI, 0.99-1.02; P = .24]
  • Viral: 6.83% vs 5.74% (RR, 1.19; 95% CI, 1.15-1.23; P < .0001)
  • Skin: 5.99% vs 4.73% (RR, 1.26; 95% CI, 1.22-1.32; P < .0001)
  • Fungal: 6.30% vs 4.88% (RR, 1.29; 95% CI, 1.24-1.34; P < .0001)
  • Opportunistic: 1.02% vs 0.68% (RR, 1.50, 95% CI, 1.35-1.66; P < .0001)

There was also a greater prevalence of inpatient hospitalizations for all infections among patients with MS vs controls (P < .0001 for all):

  • Urinary/kidney: 1.60% vs 0.36% (RR, 4.49; 95% CI, 3.98-5.08)
  • Pneumonia/influenza: 0.77% vs 0.35% (RR, 2.22; 95% CI,1.94-2.54)
  • Other respiratory/throat: 0.43% vs 0.18% (RR, 2.37; 95% CI, 1.97-2.85)
  • Viral: 0.23% vs 0.09% (RR, 2.58; 95% CI, 1.99-3.36)
  • Skin: 0.57% vs 0.29% (RR, 1.95; 95% CI, 1.68-2.27)
  • Fungal: 0.32% vs 0.09% (RR, 3.69; 95% CI, 2.86-4.77)
  • Opportunistic: 0.07% vs 0.04% (RR, 1.94; 95% CI, 1.26-2.97)

Among the patients with MS, the mean (SD) age was 47.3 (10.5) years and all had at least 2 diagnoses of MS (indicated by International Classification of Disease, Ninth Edition, Clinical Modification or ICD-10-CM codes) at least 30 days apart. Controls had 2 diagnoses, at least 30 days apart, for other conditions. Patients were excluded if they had an antibiotic or antiviral claim in the 60 days prior to their baseline visit or had a claim for pregnancy, inpatient residential care, end-stage renal disease facility, HIV, or hepatitis C virus. Most patients in each group (75.7%) were female, 65.7% had commercial insurance, and 34.3% had self-insured employer insurance.

"These findings, from a modern US-based cohort, support an elevated risk for a number of infection types in patients with MS," said lead investigator Riley Bove, MD, of the Weill Institute for Neurosciences at the University of California, San Francisco. “Specifically, the elevated risk of urinary and kidney infections points to a need for better screening and management of bladder function."

A principal limit on these results is that they only represent patients with commercial health insurance, so generalizing them to patients with other insurance types may be difficult. Unmeasured confounders were also possible.

The top reasons given for the higher infection risks seen, especially for urinary and kidney infections, were patients’ immune-suppressing or modulating drugs, MS’ effect on other organ systems, and barriers to care from poor health.


Bove R, Slaton T, Kozma CM, et al. Risk of specific infections in patients with multiple sclerosis versus matched controls: an analysis of administrative claims data. Presented at: ACTRIMS Forum 2021; February 24-26, 2021. Accessed March 17, 2021. https://www.abstractsonline.com/pp8/#!/9245/presentation/116

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