55.10 A Nationwide Analysis of Outcomes in Patients with Myasthenia Gravis Undergoing Non-Thymic Surgery

R. H. Hollis1, L. N. Wood1, J. S. Richman1, M. S. Morris1, D. I. Chu1  1University Of Alabama at Birmingham,Surgery,Birmingham, Alabama, USA

Introduction:
Patients with myasthenia gravis (MG) are at risk of myasthenia crisis when subjected to stress.  We examined the frequency of major, non-thymic surgery in patients with MG and hypothesized that MG would be associated with higher rates of postoperative complications, specifically respiratory failure.

Methods:
Patients undergoing colectomy, coronary artery bypass grafting (CABG), hysterectomy, and total hip replacement during 2012-2013 were identified in the Nationwide Inpatient Sample.  The primary outcome was inpatient respiratory failure; secondary outcomes included a composite of other inpatient complications and mortality.  Logistic regression was used to examine the association between MG and complications adjusting for patient, procedure, and hospital factors.  

Results:
Among 2,227,310 patients undergoing one of the four surgical procedures, 1780 (0.08%) had a history of MG.  The proportion of patients with MG was highest for colectomy (0.14%; n=670) followed by total hip replacement (0.08%; n=740), CABG (0.06%; n=210), and hysterectomy (0.03%; n=160).   The respiratory failure rate was 3.2%.  Additional inpatient complications occurred in 13.7% and mortality occurred in 1.5%.  In adjusted analyses, MG was associated with higher odds of respiratory failure compared to non-MG patients (OR 1.68; 95%CI 1.11-2.54).  However, patients with MG had similar adjusted odds of other complications (OR 1.03; 95%CI 0.75-1.40) and mortality (OR 0.69; 95%CI 0.32-1.50) compared to patients without MG.  Plasma exchange or intravenous immunoglobulin administration was utilized in only 3.6% of patients with MG.

Conclusion:

Patients with MG undergo major, non-thymic surgical procedures and are associated with significantly higher risk of inpatient respiratory failure, but not mortality or other complications.