Utility of the ROX Index in Predicting Intubation for Patients With COVID-19–Related Hypoxemic Respiratory Failure Receiving High-Flow Nasal Therapy: Retrospective Cohort Study

Abstract

Background The use of high-flow nasal therapy (HFNT) to treat COVID-19 pneumonia has been greatly debated around the world due to concerns about increased health care worker transmission and delays in invasive mechanical ventilation (IMV). Herein, we analyzed the utility of the noninvasive ROX (ratio of oxygen saturation) index to predict the need for and timing of IMV. Objective This study aimed to assess whether the ROX index can be a useful score to predict intubation and IMV in patients receiving HFNT as treatment for COVID-19–related hypoxemic respiratory failure. Methods This is a retrospective cohort analysis of 129 consecutive patients with COVID-19 admitted to Temple University Hospital in Philadelphia, PA, from March 10, 2020, to May 17, 2020. This is a single-center study conducted in designated COVID-19 units (intensive care unit and other wards) at Temple University Hospital. Patients with moderate and severe hypoxemic respiratory failure treated with HFNT were included in the study. HFNT patients were divided into two groups: HFNT only and intubation (ie, patients who progressed from HFNT to IMV). The primary outcome was the value of the ROX index in predicting the need for IMV. Secondary outcomes were mortality, rate of intubation, length of stay, and rate of nosocomial infections in a cohort treated initially with HFNT. Results Of the 837 patients with COVID-19, 129 met the inclusion criteria. The mean age was 60.8 (SD 13.6) years, mean BMI was 32.6 (SD 8) kg/m², 58 (45%) were female, 72 (55.8%) were African American, 40 (31%) were Hispanic, and 48 (37.2%) were nonsmokers. The mean time to intubation was 2.5 (SD 3.3) days. An ROX index value of less than 5 at HFNT initiation was suggestive of progression to IMV (odds ratio [OR] 2.137, P=.052). Any further decrease in ROX index value after HFNT initiation was predictive of intubation (OR 14.67, P<.001). Mortality was 11.2% (n=10) in the HFNT-only group versus 47.5% (n=19) in the intubation group (P<.001). Mortality and need for pulmonary vasodilators were higher in the intubation group. Conclusions The ROX index helps decide which patients need IMV and may limit eventual morbidity and mortality associated with the progression to IMV.

Comparison of ROX, HROX, and delta-HR indices to predict successful weaning from high-flow oxygen therapy in hospitalized patients with COVID-19 pneumonia

“…Additionally, an ROX greater than 4.88 measured at 2 h after HFNC initiation had a significant association with a lower risk for intubation [ 12 ]. In line with the findings of the retrospective cohort study involving 129 patients with COVID-19 pneumonia conducted by Patel M et al [ 13 ], the study indicated that an ROX index value of less than 5 at the initiation of HFNC suggested a progression to invasive mechanical ventilation (odds ratio 2.137, P = .052). Furthermore, any subsequent decrease in the ROX index value after HFNC initiation was predictive of intubation (OR 14.67, P < .001).…”

The role of ROX index–based intubation in COVID-19 pneumonia: a cross-sectional comparison and retrospective survival analysis

“…The ROX index is a simple scoring system devised to predict the failure of HFNO in acute hypoxemic respiratory failure [ 5 ]; it has shown utility in not just predicting intubation in COVID-19, but also the need for hospital admission [ 19 ]. Patel et al [ 20 ] studied the utility of the ROX index in predicting the need for IMV in COVID-19 pneumonia patients and found that a score <5 at initiation predicted the need for IMV (odds ratio [OR], 2.137; P=0.052) . The mean time to intubation was 2.5 days with 47% mortality in patients requiring IMV.…”

Peer Review of “Utility of the ROX Index in Predicting Intubation for Patients With COVID-19–Related Hypoxemic Respiratory Failure Receiving High-Flow Nasal Therapy: Retrospective Cohort Study”

“…This paper [ 1 ] is an important resource for the use of high-flow nasal cannula in patients with COVID-19 and provides important insights on the current COVID-19 pandemic. Respiratory support for patients with COVID-19 is an important topic for critical patients.…”