Table 2.
Validation studies of combined and intraoperative models
| Ref. | Period + number | Sample region | Operation | Characteristics | Source of data | Models tested | Outcomes tested |
| Zafirellis et al[36], 2002 | 1990-1999 (204) | United Kingdom | TT/TH | N: 39/204; H: 156AC/45SCC | Single centre | POSSUM | Major morbidity + Mortality |
| Lai et al[37], 2007 | 2001-2005 (545) | China | TT | N: N/A; H: 545SCC/0AC | Hong Kong (All) | POSSUM; O-POSSUM; P-POSSUM | Mortality |
| Lagarde et al[38], 2007 | 1993-2005 (663) | Netherlands | TT/TH | N: N/A; H: 476AC/187SCC | Single centre | O-POSSUM | Mortality |
| Baba et al[39], 2008 | 2000-2007 (142) | Japan | TT | N: 15/142; H: 142SCC/0AC | Single centre | E-PASS | Morbidity |
| Bosch et al[33], 2011 | 1991-2007 (278) | Netherlands | TT | N: 10/278; H: 235AC/43SCC | Single centre | ACCI; CCI; O-POSSUM; P-POSSUM | Mortality |
| Yoshida et al[40], 2013 | 2005-2012 (308) | Japan | TT | N: N/A; H: N/A | Single centre | E-PASS | Morbidity |
| Filip et al[34], 2014 | 2004-2013 (43) | Romania | TT/TH | N: 22/43; H: 33SCC/9AC | Single centre | ACCI; CCI; POSSUM; O-POSSUM; P-POSSUM | Mortality |
| Filip et al[32], 2015 | 2008-2012 (167) | Italy | TT/TH/MIE | N: 131/167; H: 105 AC/62SCC | Single centre | PNI-multivariate PNI; CCI; ACCI; O-POSSUM; P-POSSUM; Amsterdam score | Morbidity |
| Yamana et al[35], 2015 | 2005-2013 (251) | Japan | TT/MIE | N: 150/251; H: N/A | Single centre | GNRI; PNI; E-PASS; POSSUM | Respiratory complications |
| Xing et al[41], 2016 | 2008-2010 (189) | China | TT/TH | N: 7/189; H: 141SCC/45AC | Single centre | E-SAS | Major morbidity |
| Eto et al[42], 2016 | 2007-2015 (399) | Japan | Hybrid | N: 176/399; H: N/A | Single centre | SAS | Major morbidity |
| Nakagawa et al[43], 2017 | 2007-2017 (379) | Japan | TT/Hybrid/MIE | N: 129/379; H: 367SCC/12AC | Single centre | SAS | Major morbidity |
| Aoki et al[44], 2019 | 2011-2015 (246) | Japan | TT/Hybrid/MIE | N: 152/246; H: N/A | Single centre | E-SAS; Modified E-SAS | Major morbidity |
| Hayashi et al[45], 2019 | 2012-2016 (190) | Japan | TT | N: 115/190; H: N/A | Single centre | SAS | Major morbidity |
TT: Transthoracic; TH: Transhiatal; MIE: Minimally invasive esophagectomy; N: Neoadjuvant status; H: Histopathology; N/A: Not applicable; SCC: Squamous cell carcinoma; AC: Adenocarcinoma; eSAS: Esophagectomy surgical Apgar score; SAS: Surgical Apgar score; IPF: Intraoperative factors; POSSUM: Physiological and operative severity score for the enumeration of mortality and morbidity; P-POSSUM: Portsmouth physiological and operative severity score for the enumeration of mortality and morbidity; O-POSSUM: Oesophagogastric physiological and operative severity score for the enumeration of mortality and morbidity; E-PASS: Estimation of physiologic ability and surgical stress; ACCI: Age adjusted charlson comorbidity index; CCI: Charlson comorbidity index; PNI: Prognostic nutritional index; GNRI: Geriatric nutritional risk index.