Intensive care due to myasthenia gravis: Risk factors and prognosis

Abstract

Background and purpose: Exacerbation of myasthenia gravis (MG) with respiratory failure requires intensive care. We aimed to study the risk factors for intensive care unit admission for MG exacerbation and myasthenic crisis (MC) and the prognosis of people with MG (pwMG) thereafter.

Methods: This retrospective study investigated patients in the Helsinki and Uusimaa hospital district during the years 2008-2021. PwMG (International Classification of Diseases, 10^th revision code G70.0) were identified through a data repository search, followed by a chart review of patient records. Risk factors for intensive care due to MG exacerbation were evaluated as compared with the patients only treated in the outpatient clinic and those treated in the neurological ward for MG exacerbation. The outcomes of patients in intensive care for any reason were also compared with those of patients in intensive care for exacerbation of bronchial asthma.

Results: Of 577 pwMG, 35 (6.1%) needed intensive care for MG within a median of 5.3 months from diagnosis. The mean (±SD) age at MG diagnosis was higher in the intensive care group (60.5 [±16.1] years) compared to the outpatient (48.3 [±20.9] years; p < 0.001) and neurological ward groups (53.4 [±20.8] years; p = 0.044). Thymoma (odds ratio [OR] 4.8, 95% confidence interval [CI] 1.19-19.43; p = 0.028) and female sex (OR 2.1, 95% CI 1.02-4.48; p = 0.045) were independent risk factors for intensive care. In-hospital mortality was 4% for MC patients. Six-month mortality after intensive care for MG exacerbation (14.3%) was twice that for asthma exacerbation (7.7%).

Conclusion: Our study shows an increased risk of intensive care treatment for patients with late-onset MG, female sex or thymoma, occurring usually within 6 months from diagnosis, which emphasises the importance of early treatment choices.

Keywords: exacerbation; intensive care; myasthenia gravis; myasthenic crisis; risk factors.

FIGURE 1

Study subgroups. Flow chart showing data acquisition and formation of the study subgroups. The main subgroups of the study are highlighted. There was partial overlap between people with myasthenia gravis (pwMG) in intensive care for reasons other than myasthenia gravis (MG) and hospital ward groups; some pwMG in intensive care for MG also had episodes in regular or neurological wards. The total number 577 of pwMG included the intensive care group, neurological ward group, outpatient care group, and patients in regular wards, to exclude duplicates. In intensive care for other reasons were 99 of 167 pwMG who did not come up in other groups, and they were excluded from the comparisons due to the possibility of MG affecting the intensive care admission. MC, myasthenic crisis.