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Table 1 Characteristics of the included studies

From: Predictive power of extubation failure diagnosed by cough strength: a systematic review and meta-analysis

Author Year Country Design Method of SBT Measurement of cough strength Definition of weak cough Total tests TP FP FN TN Time and definition of extubation failure
Beuret 2009 France Prospective T-piece Voluntary CPF tested with an external flowmeter CPF ≤ 35 L/min 130 11 34 3 82 48 h Reintubation
Duan 2014a China Prospective PSV Voluntary CPF tested with an external flowmeter CPF ≤ 62.4 L/min 115 17 34 3 61 72 h Reintubation
Duan 2014b China Prospective PSV #Involuntary CPF tested with an external flowmeter CPF ≤ 49.8 L/min 115 14 32 6 63 72 h Reintubation
Gao 2009a China Prospective PSV/CPAP Voluntary CPF tested with a ventilator CPF ≤ 58.5 L/min 200 20 55 8 117 72 h Reintubation/death
Gao 2009b China Prospective PSV/CPAP SCSS (strong, moderate, weak) Weak 200 13 3 15 169 72 h Reintubation/death
Salam 2004a USA Prospective T-piece/PSV Voluntary CPF tested with an external flowmeter CPF ≤ 60 L/min 88 11 25 3 49 72 h Reintubation
Salam 2004b USA Prospective T-piece/PSV WCT Negative 88 10 36 4 38 72 h Reintubation
Smailes 2013 UK Prospective T-piece Voluntary CPF tested with an external flowmeter CPF ≤ 60 L/min 125 10 7 7 101 48 h Reintubation
Smina 2003 USA Prospective T-piece/PSV Voluntary CPF tested with an external flowmeter CPF ≤ 60 L/min 111 9 25 4 73 72 h Reintubation
Su 2010a China Prospective T-piece/PSV/CPAP #Involuntary CPF tested with an external flowmeter CPF ≤ 58.5 L/min 150 25 25 7 93 Hospital stay Reintubation
Su 2010b China Prospective T-piece/PSV/CPAP SCSS (strong, weak, no cough) Weak or no cough 150 25 47 7 71 Hospital stay Reintubation
Khamiees 2001a China Prospective T-piece/PSV/CPAP SCSS (grade 0 to 5) Grade 0 to 2 100 10 14 8 68 72 h Reintubation
Khamiees 2001b China Prospective T-piece/PSV/CPAP WCT Negative 100 9 16 9 66 72 h Reintubation
Huang 2013 China Retrospective T-piece/PSV SCSS (effective and ineffective) Ineffective 119 23 27 4 65 7 d Reintubation
Gobert 2017 France Prospective PSV Voluntary CPF tested with a ventilator CPF ≤ 60 L/min 92 7 24 4 57 48 h Reintubation/death
Liu 2014 China Prospective PSV Voluntary CPF tested with a ventilator CPF ≤ 60 L/min 102 8 36 7 51 48 h Reintubation
Duan 2015a China Prospective PSV SCSS (grade 0 to 5) Grade 0 to 2 186 16 52 12 106 72 h Reintubation
Duan 2015b China Prospective PSV Voluntary CPF tested with an external flowmeter CPF ≤ 60 L/min 186 23 71 5 87 72 h Reintubation
Bai 2017a China Prospective PSV Voluntary CPF tested with an external flowmeter CPF ≤ 56.4 L/min 126 11 14 4 97 72 h Reintubation
Bai 2017b China Prospective PSV Voluntary CPF tested with an external ventilator CPF ≤ 56 L/min 126 11 16 4 95 72 h Reintubation
Xiao 2018 China Prospective PSV Voluntary CPF tested with an external flowmeter CPF ≤ 60 L/min 139 15 36 7 81 72 h Reintubation
Duan 2017 China Prospective PSV Voluntary CPF tested with an external flowmeter CPF ≤ 70 L/min 356 61 119 15 161 7 d Reintubation
Thille 2015 France Prospective PSV SCSS (grade 0 to 4) Grade 0 to 2 223 10 15 20 178 7 d Reintubation
Kutchak 2015 Brazil Prospective T-piece $Involuntary CPF tested with an external flowmeter CPF ≤ 80 L/min 135 35 20 10 70 48 h Reintubation
Almeida 2020a Brazil Prospective T-piece/PSV Voluntary CPF tested with an external flowmeter CPF ≤ 45 L/min 81 23 3 10 45 48 h Reintubation
Almeida 2020b Brazil Prospective T-piece/PSV #Involuntary CPF tested with an external flowmeter CPF ≤ 60 L/min 81 29 4 4 44 48 h Reintubation
Almeida 2020c Brazil Prospective T-piece/PSV $Involuntary CPF tested with an external flowmeter CPF ≤ 55 L/min 81 30 7 3 41 48 h Reintubation
Aziz 2018 Egypt Prospective Not reported SCSS (grade 0 to 5) Grade 0 to 2 80 18 3 19 40 72 h Reintubation
Vivier 2019a France Prospective T-piece SCSS (ineffective, moderate, and effective) Ineffective 181 6 7 27 141 7 d Reintubation/death
Vivier 2019b France Prospective T-piece Voluntary CPF tested by an external flowmeter CPF ≤ 60L/min 160 18 74 10 58 7 d Reintubation/death
Wang 2019 China Retrospective Not reported SCSS (with or without spontaneous cough) Without spontaneous cough 86 19 0 6 61 Hospital stay Reintubation
Ma 2018 China Retrospective Not reported SCSS (strong, weak, no cough) Weak or no cough 108 11 6 8 83 48 h Reintubation
Frutos-Vivar 2006 Canada Prospective T-piece/PSV/CPAP SCSS (poor, moderate, or excellent) Poor 900 33 178 88 601 72 h Reintubation
Jaber 2018 France Prospective T-piece/PSV/CPAP SCSS (weak and strong) Weak 1505 116 811 32 546 48 h Reintubation
Dos 2017 Brazil Prospective T-piece/PSV SCSS (grade 0 to 5) Grade 0 to 2 311 8 21 35 247 48 h Reintubation
Michetti 2018 USA Prospective PSV/CPAP SCSS (not strong and strong) Not strong 464 11 142 24 287 96 h Reintubation
Abbas 2018 Egypt Prospective Not reported SCSS (grade 0 to 5) Grade 0 to 2 90 7 11 19 53 48 h Reintubation/NIV
Norisue 2020 Japan Prospective PSV Voluntary CPF tested with a ventilator CPF ≤ 50 L/min 252 8 62 4 178 72 h Reintubation
Sanson 2018 Italy Prospective Not reported SCSS (strong, weak, no cough) Weak or no cough 205 21 121 5 58 ICU stay Reintubation/NIV
Wang 2009a China Prospective PSV SCSS (grade 0 to 5) Grade 0 to 2 68 9 9 11 39 72 h Reintubation
Wang 2009b China Prospective PSV WCT Negative 68 10 11 10 37 72 h Reintubation
Elkholy 2021 Egypt Prospective PSV WCT Negative 150 21 24 1 104 72 h Reintubation
Lu 2010 China Prospective PSV Voluntary CPF tested with an external flowmeter CPF ≤ 29.35 L/min 19 7 4 0 8 72 h Reintubation
Liang 2019 China Prospective PSV #Involuntary CPF tested with a ventilator CPF ≤ 71.15 L/min 48 8 4 2 34 48 h Reintubation/death
Thille 2020 France Prospective T-piece/PSV SCSS (grade 0 to 4) Grade 0 to 1 284 11 16 45 212 7 d Reintubation/death
  1. Letters a, b, and c after the year (e.g. 2014a and 2014b) represent different arms of a given study
  2. #Cough was stimulated with 2 mL normal saline
  3. $Cough was stimulated with suction catheter
  4. CPF = cough peak flow, SCSS = semiquantitative cough strength score, WCT = white card test, TP = true positive, FP = false positive, FN = false negative, TN = true negative, NIV = noninvasive ventilation, SBT = spontaneous breathing trial, PSV = pressure support ventilation, CPAP = continuous positive airway pressure
  5. Sensitivity = true positives/(true positives + false negatives). Specificity = true negatives/(true negatives + false positives)
  6. True positives were patients with ineffective cough who failed extubation. False negatives were patients with effective cough who failed extubation
  7. True negatives were patients with effective cough who were successfully extubated. False positives were patients with ineffective cough who were successfully extubated