Coefficients and constant to calculate the ECoRRS score
| Predictor | Coefficient |
| FiO2 (as fraction) | 7.060×10−4 |
| Initial red blood cell count (million/µL) | 1.950×10−5 |
| SpO2-max (%) | 1.045×10−4 |
| Current lymphocyte count (thousand/µL) | 6.765×10−5 |
| Temperature (°C) | 2.955×10−5 |
| Body weight (kg) | −1.117×10−5 |
| Constant (C0) | 0.08 |
Based on the LASSO model, the score is calculated by summing the value of each predictor multiplied by its coefficient and adding the constant (C0). If necessary, FiO2 is estimated as 0.21 (room air) plus an additional 0.04 for each 1 L/min increase in oxygen flow rate.33 Positive values predict intubation within the next 48 hours, and negative values predict no intubation within the next 48 hours. The greater the magnitude of the score, the greater the certainty of the prediction.
ECoRRS, Early COVID-19 Respiratory Risk Stratification; FiO2, fraction of inspired oxygen; SpO2-max, maximum oxygen saturation for the 4-hour block.