Health Disparities in Extracorporeal Membrane Oxygenation Utilization and Outcomes: A Scoping Review and Methodologic Critique of the Literature*

Abstract

Objectives: To map the scope, methodological rigor, quality, and direction of associations between social determinants of health (SDoH) and extracorporeal membrane oxygenation (ECMO) utilization or outcomes. Data Sources: PubMed, Web of Science, Embase, and Cochrane Library databases were systematically searched for citations from January 2000 to January 2023, examining socioeconomic status (SES), race, ethnicity, hospital and ECMO program characteristics, transport, and geographic location (context) with utilization and outcomes (concept) in ECMO patients (population). Study Selection: Methodology followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses scoping review extension. Two reviewers independently evaluated abstracts and full text of identified publications. Exclusion criteria included non-English, unavailable, less than 40 patients, and periprocedural or mixed mechanical support. Data Extraction: Content analysis used a standardized data extraction tool and inductive thematic analysis for author-proposed mediators of disparities. Risk of bias was assessed using the Quality in Prognosis Studies tool. Data Synthesis: Of 8,214 citations screened, 219 studies were identified. Primary analysis focuses on 148 (68%) including race/ethnicity/SES/payer variables including investigation of ECMO outcomes 114 (77%) and utilization 43 (29%). SDoH were the primary predictor in 15 (10%). Overall quality and methodologic rigor was poor with advanced statistics in 7%. Direction of associations between ECMO outcomes or utilization according to race, ethnicity, SES, or payer varied. In 38% adverse outcomes or lower use was reported in underrepresented, under-resourced or diverse populations, while improved outcomes or greater use were observed in these populations in 7%, and 55% had no statistically significant result. Only 26 studies (18%) discussed mechanistic drivers of disparities, primarily focusing on individual- and hospital-level rather than systemic/structural factors. Conclusions: Associations between ECMO utilization and outcomes with SDoH are inconsistent, complicated by population heterogeneity and analytic shortcomings with limited consideration of systemic contributors. Findings and research gaps have implications for measuring, analyzing, and interpreting SDoH in ECMO research and healthcare.