Supplementary Material for: Are There Racial Differences in Inpatient Outcomes and Treatment Utilization Following Hospitalization for Myasthenia Gravis Exacerbation?

Introduction
Racial differences in healthcare utilization and outcomes in the United remain an important issue. Little is known about racial differences in inpatient outcomes following hospitalizations for myasthenia gravis (MG). In this study, we used a claim-based database to assess racial differences in outcomes in hospitalized myasthenics.

Methods
The 2006 to 2014 National Inpatient Sample (NIS) database was queried using the International Classification of Diseases 9th Edition (ICD-9) diagnosis code (358.01) to identify adult patients (age >17 years) undergoing hospitalization for MG. Race was categorized into – White, Black/African American, Asian or Pacific Islander, Hispanic, Native American, and other. Complications assessed included urinary tract infections, acute renal failure, cardiac complications, systemic infection, deep venous thrombosis, and pulmonary embolism. Multivariate logistic regression analyses were used to assess whether race was associated with a difference in outcomes, after controlling for baseline demographics, hospital characteristics and treatment factors. For regression purposes, White race was used as the reference.

Results
A total of 56,189 patient admissions, using a weighted sample, underwent hospitalization for MG between 2006 to 2014. Black/ African American patients had significantly higher odds of experiencing systemic infections (OR 1.35 [95% CI 1.16-1.58]; p<0.001), deep venous thrombosis (OR 2.11 [95% CI 1.36-3.27]; p=0.001) and renal failure (OR 1.19 [95% CI 1.05-1.35]; p=0.005). Black/African American patients were more likely to be intubated (OR 1.09 [95% CI 1.01-1.19]; p=0.028) and receive non-invasive mechanical ventilation (OR 1.62 [95% CI 1.46-1.79]; p<0.001), however, were less likely to receive IVIG (OR 0.77 [95% CI 0.73-0.82]; p<0.001) and plasmapheresis (OR 0.77 [95% CI 0.72-0.82]; p<0.001). Black/African American and Hispanic patients had lower mortality (OR 0.74 [95% CI 0.59-0.94; p=0.012].

Conclusions
Significant racial differences exist in both treatment utilization and inpatient outcomes for patients hospitalized for MG.