Pooled analysis of secondary outcome measures
| Outcome measure | No. of patients | No. of trials | MD or RR (95% CI) | I2 value, % | Interaction p value |
|---|---|---|---|---|---|
| Pao2:Fio2 ratio, mm Hg | 0.002* | ||||
| HFNC v. conventional oxygen therapy | 832 | 3 | 4.72 (–28.90 to 38.33) | 90 | < 0.001† |
| Low risk | 2 | −15.41 (−42.68 to 11.85) | 87 | ||
| High risk | 1 | 63.10 (25.65 to 100.55) | |||
| HFNC v. NIV | 1086 | 3 | −53.84 (−71.43 to −36.24) | 44 | 0.07† |
| Low risk | 2 | −60.05 (−72.75 to −47.34) | 0 | ||
| High risk | 1 | −21 (−61.33 to 19.33) | |||
| Paco2 level, mm Hg | 0.9* | ||||
| HFNC v. conventional oxygen therapy | 832 | 3 | −0.40 (−2.54 to 1.74) | 71 | 0.01† |
| Low risk | 2 | 0.69 (−0.31 to 1.69) | 0 | ||
| High risk | 1 | −4.10 (−2.54 to 1.74) | |||
| HFNC v. NIV | 1086 | 3 | −0.53 (−2.34 to 1.28) | 62 | 0.3† |
| Low risk | 2 | −0.18 (−2.22 to 1.86) | 77 | ||
| High risk | 1 | −3.00 (−7.66 to 1.66) | |||
| Arterial pH | 0.8* | ||||
| HFNC v. conventional oxygen therapy | 727 | 2 | 0.00 (−0.03 to 0.03) | 37 | |
| HFNC v. NIV | 1046 | 2 | 0.01 (−0.00 to 0.02) | 24 | |
| Respiratory rate, breaths/min | 0.1* | ||||
| HFNC v. conventional oxygen therapy | 305 | 2 | −3.68 (−6.81 to −0.55) | 83 | |
| HFNC v. NIV | 1046 | 2 | −1.13 (−2.01 to −0.25) | 8 | |
| ICU mortality | 0.6* | ||||
| HFNC v. conventional oxygen therapy | 859 | 4 | 0.79 (0.44 to 1.40) | 0 | 0.4† |
| Low risk | 3 | 0.68 (0.35 to 1.33) | 0 | ||
| High risk | 1 | 1.18 (0.38 to 3.62) | |||
| HFNC v. NIV | 993 | 2 | 0.79 (0.31 to 2.05) | 74 | |
| Length of ICU stay, d | 0.9* | ||||
| HFNC v. conventional oxygen therapy | 832 | 3 | 0.02 (−0.26 to 0.30) | 0 | 0.5† |
| Low risk | 2 | 0.01 (−0.27 to 0.29) | 0 | ||
| High risk | 1 | 1.30 (−2.29 to 4.89) | |||
| HFNC v. NIV | 1046 | 2 | 0.00 (−0.20 to 0.20) | 0 | |
| Pneumothorax rate | |||||
| HFNC v. NIV | 830 | 1 | 1.15 (0.42 to 3.14) |
Note: APACHE = Acute Physiologic Assessment and Chronic Health Evaluation, CI = confidence intervals, HFNC = high-flow nasal cannula oxygen therapy, ICU = intensive care unit, MD = weighted mean difference, NIV = noninvasive ventilation, Paco2 = partial pressure of arterial carbon dioxide, Pao2:Fio2 = ratio of partial pressure of arterial oxygen to fraction of inspired oxygen, RR = risk ratio, SAPS = Simplified Acute Physiology Score.
↵* Denotes p value of subgroup analyses according to type of oxygen therapy used in control group.
↵† Denotes p value of subgroup analyses according to disease severity of participants (low risk = APACHE II score < 15 or SAPS II score < 30).