Independent risk factors for in-hospital outcome of myasthenic crisis: a prospective cohort study.

Background: Myasthenic crisis (MC) is a life-threatening condition for myasthenia gravis (MG). Therapeutic plasma exchange (TPE) and intravenous immunoglobulin (IVIg) efficaciously treat patients with MC. However, not every MC responds well to rescue therapies, and the determinants for outcome with the evidence from prospective cohorts are still lacking.

Objectives: To explore the risk factors for in-hospital outcomes in patients with MC.

Methods: Using a national neuromuscular center-based cohort of MG with prospective follow-ups from the crisis to the post-crisis phase, we finally included 90 MC episodes from 76 independent patients who received a standard regimen of rescue therapies.

Results: The mean admission age was 52.89 ± 15.72 years. With a female predominance of 63.16% (48/76) and a high proportion of thymoma-associated MG (TMG) of 63.16% (48/76), the overall in-hospital mortality was 2.63% (2/76) and the average duration for mechanical ventilation (MV) use was 17.09 ± 13.36 days (0-53 days). In contrast to the patients with anti-acetylcholine receptor (AChR) antibodies, muscle-specific tyrosine kinase (MuSK)-associated MC exhibited a shorter MV support (5.20 ± 5.07 versus 17.40 ± 13.24 days, p = 0.023), length of intensive care units (ICU) stay (6.00 ± 4.64 versus 19.16 ± 17.54 days, p = 0.046), and hospital stay (16.00 ± 4.12 versus 34.43 ± 20.48 days, p = 0.011). Thymoma [odds ratio (OR): 0.200, 95% confidence interval (CI): 0.058-0.687, p = 0.011], partial pressure of carbon dioxide (PCO₂) in blood gas before MV (OR: 1.238, 95% CI: 1.015-1.510, p = 0.035), and pneumonia (OR: 0.204, 95% CI: 0.049-0.841, p = 0.028) were identified as independent risk factors for prolonged MV use. TMG patients with thymoma burden exhibited a notable longer MV use (22.08 ± 17.54 versus 8.88 ± 6.79 days, p = 0.001), a prolonged hospital stay (40.40 ± 26.13 versus 23.67 ± 13.83 days, p = 0.009) compared with non-TMG. Even with complete thymoma resection (R0), TMG exhibited an unfavorable outcome versus non-TMG.

Conclusion: With timely rescue therapies and prospective follow-ups, the in-hospital outcome of MCs was substantially improved. Thymoma, PCO₂ in blood gas before MV, and pneumonia were identified as independent risk factors for prolonged MV use.