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Table 2 Summary of stratified analyses of pooled risk ratios

From: Associations between positive end-expiratory pressure and outcome of patients without ARDS at onset of ventilation: a systematic review and meta-analysis of randomized controlled trials

Stratified analysis No. of trials No. of patientsa Risk ratio (95% CI) SMD (95% CI) p value I 2 (p value)
In-hospital mortality
Level of PEEP      
 High PEEP versus ZEEP 5 404 0.83 (0.62–1.11) 0.20 0% (0.57)
Type of patient      
 Medical patients 5 399 0.82 (0.62–1.09) 0.17 0% (0.73)
Level of PEEP      
 ≥10 Versus <10 cmH2O 3 131 2.04 (0.19–21.85) 0.56 77% (0.04)
28-Day mortality      
Level of PEEP      
 High PEEP versus ZEEP 1 63 0.82 (0.47–1.45) 0.50 NA
Type of patient      
 Medical patients 2 183 0.55 (0.26–1.18) 0.12 76% (0.04)
Level of PEEP      
 ≥10 versus <10 cmH2O 1 120 0.38 (0.24–0.62) <0.001 NA
Duration of ventilation
Level of PEEP      
 High PEEP versus ZEEP 2 87 0.89 (−0.95–2.73) 0.34 91% (< 0.01)
Type of patient      
 Medical patients 2 101 0.17 (−0.25–0.60) 0.43 13% (0.28)
Level of PEEP      
 ≥10 versus <10 cmH2O 1 38 0.45 (−0.20–1.09) 0.18 NA
ARDS      
Level of PEEP      
 High PEEP versus ZEEP 4 410 0.43 (0.21–0.91) 0.03 56% (0.08)
Type of patient      
 Medical patients 3 298 0.52 (0.27–1.02) 0.06 50% (0.13)
Level of PEEP      
 ≥10 versus <10 cmH2O 0 0 NA NA NA
Pneumonia      
Level of PEEP      
 High PEEP versus ZEEP 3 331 0.58 (0.29–1.15) 0.12 58% (0.09)
Type of patient      
 Medical patients 2 219 0.64 (0.24–1.66) 0.36 72% (0.06)
Level of PEEP      
 ≥10 versus <10 cmH2O 0 0 NA NA NA
Atelectasis      
Level of PEEP      
 High PEEP versus ZEEP 3 331 0.74 (0.33–1.66) 0.46 74% (0.02)
Type of patient      
 Medical patients 2 219 1.00 (0.54–1.84) 0.99 63% (0.10)
Level of PEEP      
 ≥10 versus <10 cmH2O 0 0 NA NA NA
Barotrauma      
Level of PEEP      
 High PEEP versus ZEEP 4 374 0.60 (0.13–2.70) 0.50 52% (0.15)
Type of patient      
 Medical patients 3 257 0.79 (0.28–2.27) 0.67 22% (0.28)
Level of PEEP      
 ≥10 versus <10 cmH2O 4 203 6.26 (0.78–50.47) 0.09 0% (0.46)
PaO 2 /FiO 2 ratio      
Level of PEEP      
 High PEEP versus ZEEP 2 143 0.63 (0.29–0.96) < 0.01 0% (0.79)
Type of patient      
 Medical patients 2 247 1.17 (0.06–2.28) 0.04 94% (< 0.01)
Level of PEEP      
 ≥10 versus <10 cmH2O 4 253 0.74 (−0.14–1.61) 0.10 89% (< 0.01)
Hypoxemia      
Level of PEEP      
 High PEEP versus ZEEP 2 170 0.42 (0.19–0.92) 0.03 19% (0.27)
Type of patient      
 Medical patients 1 127 0.35 (0.20–0.61) < 0.01 NA
Level of PEEP      
 ≥10 versus <10 cmH2O 1 43 1.05 (0.16–6.77) 0.96 NA
Blood pressure      
Level of PEEP      
 High PEEP versus ZEEP NA NA NA NA NA
Type of patient      
 Medical patients 1 120 −0.92 (−1.30 to –0.54) < 0.01 NA
Level of PEEP      
 ≥10 versus <10 cmH2O 2 158 −0.21 (−1.68 to 1.26) 0.78 92% (< 0.01)
Hypotension      
Level of PEEP      
 High PEEP versus ZEEP 1 63 1.10 (0.68–1.79) 0.70 NA
Type of patient      
 Medical patients 1 63 1.10 (0.68–1.79) 0.70 NA
Level of PEEP      
 ≥10 versus <10 cmH2O 1 82 32.16 (2.04–507.16) 0.01 NA
  1. CI confidence interval, SMD standardized mean difference, ICU intensive care unit, PEEP positive end-expiratory pressure, ZEEP zero positive end-expiratory pressure, ARDS acute respiratory distress syndrome, NA not applicable
  2. aConsidering the studies included in each subgroup analysis