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Serious infections in patients with myasthenia gravis: population-based cohort study
C D Kassardjian1, J Widdifield2,3,4, J M Paterson3,4
1Division of Neurology, Department of Medicine, St Michael's Hospital, University of Toronto, Toronto, ON.
Background And Purpose:
To characterize the frequency and risk of serious infections in patients with myasthenia gravis (MG) relative to age/sex/area-matched comparators.
Methods:
This was a population-based cohort study in Ontario, Canada of patients with newly-diagnosed MG and 1:4 age/sex/area-matched general population comparators accrued from 1 April 2002 to 31 December 2015. The main outcome was a serious infection, defined by a primary diagnosis code on a hospitalization or emergency department record. We computed crude overall and sex-specific rates of infection among patients with MG and comparators, and the frequency of specific types of infection. Adjusted hazard ratios and 95% confidence intervals were estimated using Cox regression.
Results:
Among 3823 patients with MG, 1275 (33.4%) experienced a serious infection compared with 2973/15 292 (19.4%) of comparators over a mean follow-up of over 5 years. Crude infection rates among patients with MG were twice those in comparators (72.5 vs. 35.0 per 1000 person-years, respectively). The most common infection types were respiratory infections, particularly bacterial pneumonia. After adjustment for potential confounders, MG was associated with a 39% increased infection risk (adjusted hazard ratio, 1.39; 95% confidence intervals, 1.28-1.51).
Conclusions:
Patients with MG are at a significantly higher absolute and relative risk of serious infections compared with age/sex/area-matched comparators. This needs to be considered when selecting MG treatments and when planning vaccination/prophylaxis. Determining whether this risk is due to the use of immunosuppressive medications (vs. MG itself) is an important area for future research.
Insights
Patients with myasthenia gravis (MG) face double the risk of serious infections compared to the general population. This increased risk, particularly for respiratory infections, requires consideration in treatment and prevention strategies.
Area of Science:
- Neurology
- Infectious Diseases
- Epidemiology
Background:
- Myasthenia gravis (MG) is an autoimmune disorder affecting neuromuscular junctions.
- The risk of serious infections in MG patients is not fully characterized.
- Understanding infection risk is crucial for managing MG patients.
Purpose of the Study:
- To determine the frequency and risk of serious infections in patients diagnosed with myasthenia gravis (MG).
- To compare infection rates in MG patients against age, sex, and area-matched general population controls.
- To identify specific types of infections prevalent in the MG cohort.
Main Methods:
- A population-based cohort study was conducted in Ontario, Canada.
- Newly-diagnosed MG patients (n=3823) were compared to 1:4 matched controls (n=15,292).
- Serious infections were identified via hospitalization or emergency department records; Cox regression analyzed adjusted hazard ratios.
Main Results:
- MG patients had a significantly higher incidence of serious infections (33.4%) versus controls (19.4%).
- Crude infection rates were doubled in MG patients (72.5 vs. 35.0 per 1000 person-years).
- MG was associated with a 39% increased risk of serious infection (aHR, 1.39; 95% CI, 1.28-1.51), with respiratory infections being most common.
Conclusions:
- Patients with myasthenia gravis have a substantially elevated risk of serious infections.
- This heightened risk necessitates careful consideration in MG treatment selection and prophylaxis planning.
- Further research is needed to differentiate infection risk attributed to MG versus its immunosuppressive treatments.
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