Differences in Arterial Blood Gas Testing by Race and Sex Across 161 US Hospitals in 4 EHR Databases

Pulse oximetry accuracy varies across races, underscoring the importance of routine arterial blood gas (ABG) testing, the gold standard for assessing oxygen saturation. The study aimed to assess disparities in ABG testing among critically ill patients by race and sex. Records from 2001-2019 in 161 U.S. hospitals were analyzed, including Duke, MIMIC-III, MIMIC-IV, and eICU-CRD. The study evaluated ABG test incidence; time to first test; and frequency of subsequent tests, adjusting for confounders, including SOFA, hospital, and age. Subgroup analyses focused on patients with arterial lines and mechanical ventilation. The cohort included 184,178 ICU admissions (35.0% with ABG tests; 1.9% Asian, 16.5% Black, 3.5% Hispanic or Latino, 78.1% White; 45.7% female). Compared to White patients, Asian, Black, Hispanic or Latino patients were less likely to have an ABG [Odds Ratio (OR(95%CI)): 0.807 (0.741,0.879), 0.859 (0.830,0.888), 0.919 (0.865,0.976), respectively], experienced delays to initial ABG [Hazard Ratio (HR(95%CI)) Asian, 0.855(0.803,0.911); Black, 0.833(0.814,0.853), p<0.001], and were less likely to repeated ABGs [Adjusted Coefficient (95%CI): Asian 0.016 (-0.097,-0.064), Black -0.082 (-0.111-,-0.054)]. Compared to male patients, female patients received less ABG tests [OR(95%CI): 0.926(0.905-0.948)], had delays in initial testing [HR(95%CI): 0.958(0.942-0.974)], and fewer repeated ABGs [Adjusted Coefficient (95%CI): -0.051(-0.072 to -0.030)]. Findings were consistent among patients who were mechanically ventilated and had arterial lines. Asian, Black, and female patients demonstrated significantly reduced and delayed rates of ABG testing. Inequitable ABG testing may exacerbate the prevalence of hidden hypoxemia. Until skin-tone-corrected pulse oximeters are available, equitable ABG testing remains the best strategy to mitigate hidden hypoxemia.