Intubation Timing in COVID-19 Patients Based on ROX Index and Association with Patient Outcomes

Abstract

Background: Timing of intubation in COVID-19 is controversial. We sought to determine the association of ROX index defined as oxygen saturation divided by fraction of inspired oxygen divided by breathing frequency at time of intubation with clinical outcomes.

Methods: We conducted a retrospective cohort study of intubated COVID-19 patients using Cerner Real World-Data™. Multivariable logistic regression was used to evaluate the impact of ROX on mortality. We analyzed ROX as a continuous variable as well as a categorical variable using cutoffs previously described as predicting success with high flow nasal cannula.

Results: Of 1087 subjects in the analysis group, the median age was 64 years, and more than half had diabetes; 55.2% died, 1.8% were discharged to hospice, 7.8% were discharged home, 27.3% were discharged to another institution and 7.8% had another disposition. Increasing age and longer time from admission to intubation were associated with mortality. After adjusting for sex, race, age, comorbidities, and days from admission to intubation, increasing ROX score at time of intubation was associated with lower risk of death. In a logistic regression model, each increase in ROX by 1 at time of intubation was associated with an 8% reduction in odds of mortality (Odds Ratio (OR) 0.92, 95% CI 0.88-0.95). We also found an OR for death of 0.62 (95% CI 0.47-0.81) for subjects with ROX ≥ 4.88 at time of intubation.

Conclusions: Among a cohort of COVID-19 subjects who were ultimately intubated, higher ROX at time of intubation was positively associated with survival.