Table 2. Primary and Secondary Outcomes.
| Outcomes | High-flow oxygen therapy (n = 99) | Conventional oxygen therapy (n = 100) | Unadjusted absolute difference (95% CI) | Effect estimate, OR or HR (95% CI)a | P value |
|---|---|---|---|---|---|
| Primary outcomes | |||||
| Intubation within 28 d, No. (%) | 34 (34.3) | 51 (51.0) | −16.7 (−30.2 to −3.1)b | HR, 0.62 (0.39-0.96)c | .03 |
| Clinical recovery within 28 d, No. (%) | 77 (77.8) | 71 (71.0) | 6.8 (−5.3 to 18.9)b | HR, 1.39 (1.00-1.92)d | .047 |
| Time to clinical recovery, median (IQR), de | 11 (9-14) | 14 (11-19) | −3.0 (−7.5 to 1.0)f | ||
| Secondary outcomes | |||||
| Intubation within 7 d, No. (%) | 31 (31.3) | 50 (50.0) | −18.7 (−32.1 to −5.3)b | HR, 0.59 (0.38-0.94)c | .03 |
| Intubation within 14 d, No. (%) | 34 (34.3) | 51 (51.0) | −16.7 (−30.2 to −3.1)b | HR, 0.63 (0.41-0.97)c | .04 |
| Ventilation-free days at day 28, median (IQR) | 28 (19-28) | 24 (14-28) | 4.5 (0.0 to 7.8)g | OR, 2.08 (1.18-3.64) | .01 |
| Kidney replacement therapy–free days, median (IQR)h | 28 (28-28) | 28 (28-28) | 0 (0 to 0)g | OR, 1.78 (0.67-4.68) | .24 |
| Length of stay, median (IQR), d | |||||
| Intensive care unit | 7 (5-13) | 9 (5-18) | −2.0 (−6.0 to −1.0)g | OR, 0.74 (0.45-1.22) | .24 |
| Hospital | 12 (9-20) | 14 (9-23) | −2.0 (−4.0 to −1.0)g | OR, 0.77 (0.47-1.25) | .29 |
| Mortality at day 14, No. (%) | 6 (6.1) | 6 (6.0) | 0.1 (−6.6 to 6.7)b | HR, 0.93 (0.29-2.93)c | .90 |
| Mortality at day 28, No. (%) | 8 (8.1) | 16 (16.0) | −7.9 (−16.9 to 1.1)b | HR, 0.49 (0.21-1.16)c | .11 |
| Serious adverse events, No. (%) | |||||
| Cardiac arrest | 2 (2.0) | 6 (6.0) | |||
| Suprasupraventricular tachycardia or ventricular arrhythmia | 3 (3.0) | 1 (1.0) | |||
| Atelectasis | 1 (1.0) | 0 | |||
| Other reported adverse events, No. (%) | |||||
| Suspected bacterial pneumonia | 13 (13.1) | 17 (17.0) | |||
| Bacteremia | 7 (7.1) | 11 (11.0) | |||
Abbreviations: HR, hazard ratio; OR, odds ratio.
Proportional odds models are adjusted for age (≥60 or <60 years), ratio of partial pressure of arterial oxygen to fraction of inspired oxygen (Pao2/Fio2) at randomization, and comorbidities (arterial hypertension, diabetes, obesity [body mass index >30], chronic obstructive pulmonary disease, kidney failure, heart failure, and Child-Pugh class A-B liver cirrhosis). Odds ratios greater than 1 indicate benefit with use of high-flow oxygen therapy. Adjusted hazard ratios were calculated from a Cox proportional hazards model. Variables used for adjustment were the same as those listed above for odds ratios. See footnote “f” in Table 1 for Child-Pugh score and class descriptions.18
Absolute incidence differences in percentage points (percentage intubated, clinically recovered, requiring kidney replacement therapy, or who died, as appropriate).
A hazard ratio for intubation or mortality less than 1 indicates benefit with use of high-flow oxygen therapy.
A hazard ratio for clinical recovery greater than 1 indicates benefit with use of high-flow oxygen therapy. A reported lower confidence bound of 1.00 is a consequence of rounding.
Kaplan-Meier estimates of median time to clinical recovery. Time to clinical recovery was defined as the time elapsed from randomization until the first day during the 28 days after enrollment on which a patient attained a reduction of 2 or more points from their score at randomization on the modified 7-category ordinal scale (see footnote “h” in Table 1 for description of the ordinal scale).
Bootstrap 95% CI of the median difference from Kaplan-Meier estimates.
Median time-difference 95% CIs were estimated based on 5000-bootstrap resampling.
Need for kidney replacement therapy occurred in 7 patients (7.1%) randomized to high-flow oxygen therapy vs 14 (14.0%) randomized to conventional oxygen therapy (OR, 0.49; 95% CI, 0.18-1.28; P = .16).