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Infections in patients with multiple sclerosis: A national cohort study in Sweden
Anna Castelo-Branco1, Flaminia Chiesa1, Simona Conte1
1Real-world Insights, IQVIA Nordics, Pyramidvägen 7, 169 56 Solna, Sweden.
Background:
Multiple sclerosis (MS) patients have an increased risk of infections, but few population-based studies have reported infections occurring in MS in the years immediately after diagnosis.
Objective:
To explore incident infections in MS, stratified by age and sex.
Methods:
In a Swedish population-based cohort study 6602 incident MS patients (aged ≥18 years), matched at diagnosis with 61,828 matched MS-free individuals were identified between 1st January 2008 and 31st December 2016, using national registers. Incidence rates (IR) and incidence rate ratios (IRR) with 95% CI were calculated for each outcome.
Results:
The IRRs were 2.54 (95% CI 2.28-2.83) for first serious infection and 1.61 (1.52-1.71) for first non-serious infection. Compared with MS-free individuals, MS patients had higher IRs for skin, respiratory/throat infections, pneumonia/influenza, bacterial, viral, and fungal infections, with the highest IRR observed for urinary tract/kidney infections (2.44; 2.24-2.66). The cumulative incidence for most of these infections was higher among MS patients than MS-free individuals, both 0 to <5 and 5 to <9 years after index date.
Conclusion:
The burden of infections around the time of MS diagnosis and subsequent infection risk, underscore the need for careful considerations regarding the risk-benefit across different disease-modifying therapies.
Insights
Multiple sclerosis patients face a higher risk of serious and non-serious infections, particularly urinary tract and kidney infections, soon after diagnosis. This highlights the need for careful treatment decisions.
Area of Science:
- Neurology
- Infectious Diseases
- Epidemiology
Background:
- Multiple sclerosis (MS) is associated with an increased risk of infections.
- Population-based data on infections in the period immediately following MS diagnosis are limited.
Purpose of the Study:
- To investigate the incidence of infections in individuals with MS.
- To stratify infection risk by age and sex in the MS population.
Main Methods:
- A Swedish population-based cohort study included 6602 incident MS patients and 61,828 matched MS-free controls.
- Data were collected from national registers between January 2008 and December 2016.
- Incidence rates (IR) and incidence rate ratios (IRR) were calculated.
Main Results:
- MS patients had significantly higher IRRs for serious infections (2.54) and non-serious infections (1.61) compared to controls.
- Elevated risks were observed for skin, respiratory, pneumonia/influenza, bacterial, viral, and fungal infections.
- Urinary tract/kidney infections showed the highest IRR in MS patients (2.44).
- Cumulative incidence of most infections was higher in MS patients up to 9 years post-diagnosis.
Conclusions:
- A substantial burden of infections exists around the time of MS diagnosis.
- Increased infection risk post-diagnosis warrants careful consideration of treatment risks and benefits, especially concerning disease-modifying therapies.
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