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Outcomes of Minority COVID‐19 patients managed with ECMO: A single‐center experience

Abstract Background The coronavirus disease 2019 (COVID‐19) pandemic has significantly burdened the global healthcare system since December 2019. Minority populations are found to have a higher incidence of hospitalization and higher mortality when compared to Caucasians. Extracorporeal membrane oxygenation (ECMO) is reserved for COVID‐19 patients who develop respiratory failure refractory to conventional management. To our knowledge, no data has been reported on outcome differences between Minority COVID‐19 patients and Caucasian COVID‐19 patients managed with ECMO. We aimed to investigate the outcome differences between these two groups. Methods Our retrospective cohort study had 23 adults (aged 18 and older) diagnosed with COVID‐19 by polymerase chain reaction. All patients developed acute respiratory distress syndrome (ARDS), refractory to conventional treatment, and were managed on ECMO support. The primary outcome of interest was mortality; the secondary outcome was the rate of ECMO‐related complications. Results The overall mortality rate of our study was higher (70%) than other reports of the COVID‐19 population on ECMO. Caucasians in our study had more severe respiratory acidosis with carbon dioxide retention and appeared to have a higher mortality rate of 85.7% compared to Minorities (62.5%). No differences in complication rates between these two groups were identified. Conclusions Our cohort revealed a high overall mortality rate of COVID‐19 patients on ECMO support. The Caucasian group was observed to have higher mortality than the Minority group. The high overall mortality was likely attributed to the Caucasian group, which had more severe respiratory acidosis before ECMO initiation, a known predictor of poor prognosis in ARDS patients. Our cohort's ethnic composition may also partially explain the high mortality rate since COVID‐19 Minorities are reported to have worse outcomes than Caucasians. Larger and randomized studies are needed to investigate further the mortality and complication differences between Minority and Caucasian patients diagnosed with COVID‐19 and managed by ECMO.


| Statistical analysis
Baseline patient demographics (age, gender, body mass index, comorbidities, and medications), complications (pneumothorax, hemorrhage, deep vein thrombosis, pulmonary embolism [PE], thrombocytopenia, and hospital-acquired infections), and outcomes were compared between Caucasians and Minorities using SPSS, Version 27 (IBM). Continuous variables were analyzed using an analysis of variance. Categorical variables were analyzed using Fisher's exact test. Significance was determined using α = .05. All statistical tests were two-tailed.

| RESULTS
Of the 23 patients, 7 were Caucasians, and 16 were Minorities. The average age of the Minority group was 46 years old. The average age of the Caucasian group was 40 years old. Minorities and Caucasians had similar clinical characteristics and comorbidities on admission (Table 1). All patients who presented were diagnosed with COVID-19 with acute respiratory failure, and ECMO was initiated after admission.
Both groups were treated with systemic steroids, remdesivir, convalescent plasma, and empiric antibiotics during the hospitalization.
Azithromycin was the most commonly used antibiotic. All patients received thromboembolic prophylaxis and were managed on ventilators.
Pneumothorax, hemorrhage, and hematological complications such as deep venous thrombosis and PE were observed in both groups. There were no statistically significant differences in complications between the two groups (Table 2). Minorities were diagnosed with hospital-acquired infections during the ECMO course; however, no statistical differences were detected between these two groups.
At the end of the hospital course, 6 Minorities were discharged to home or long-term care facilities, and 10 Minorities were deceased. One Caucasian was discharged alive, and six Caucasians were deceased. At our center, the overall mortality rate of the combined two groups was high at 70%. Minority patients had a significantly lower in-hospital mortality rate than Caucasians (62.5% vs. 85.7%, p < .001). Additionally, Caucasian patients were observed to have a longer hospitalization course than their Minority counterparts (34 vs. 32 days, p = .014) ( Table 3). Caucasians also presented with more severe respiratory acidosis on admission (p = .007) ( patients who develop refractory respiratory or cardiac failure, 6 even though ECMO is an independent risk factor for death in COVID-19 patients. 7 Currently, the Society of Critical Care Medicine recommends using ECMO for COVID-19 patients with refractory to conventional management who have a high risk of mortality. 9 The decision of when to initiate ECMO should be made on a case-by-case basis while considering comorbidities, age, and overall prognosis.
While studies have reported that ECMO may be beneficial in treating COVID-19 patients who failed conventional management, 10 there is scant research on whether there is a difference in outcomes based on race.

| COVID-19 disease burden in Minority populations
Current research suggests that Minority populations represent a disproportionately high COVID-19 incidence burden and higher mortality rates. 11 Our cohort's ethnic composition may partially explain the observed high mortality rate. Additionally, air pollution and particulate matter (PM) concentrations tend to be higher in Minority communities. 13 In early 2020, Setti et al. 14  To our knowledge, our study is the first of its kind to report on the mortality differences between Minority and Caucasian COVID-19 populations on ECMO support. Of note, there were significant differences in respiratory status before ECMO initiation between these two groups. Caucasian patients had more severe respiratory acidosis with carbon dioxide (CO 2 ) retention (Table 4). Acidosis with CO 2 retention has been reported to be a predictor of poor prognosis. 18 The severity of respiratory acidosis is associated with mortality in ARDS patients. 19 Using the ELSO registry of 4361 hospitalized patients, Posluszny et al. 16 reported that pre-ECMO PaCO 2 is positively correlated to mortality. In Yang et al. 18  There are a few limitations of our study. Our smaller sample size may not represent the general population. Due to its retrospective nature, confounders and selection bias may exist.

| CONCLUSION
We investigated the overall mortality rate and significant complica- Abbreviation: ECMO, extracorporeal membrane oxygenation.