Table 1 Four levels of specification in primary and secondary outcomes
Level 1 Domain | Oxygenation | MV | Length of stay | Other | |||||
Level 2 Specific domain | AUC P/F ratio | AUC Spo2/FiO2 | Length of MV | Ventilator free days (VFD) up to 28 days | Hospital | ICU | 90-Day mortality | Chest x-ray index scores | Rescue therapies |
Level 3 Specific metric | Difference in AUC | Number of days | 28 days – days of MV | Number of days | Time to event | Index scores over period of MV | Number of therapies used | ||
Level 4 Method of aggregation | Comparisons of the of means of AUC | Comparisons of the means of number of days | Comparisons of the means of VFD | Comparisons of the means of length of stay | Comparison on number of 90-day mortality | Comparison of index scores over time | Comparison of rescue therapies used. | ||