Table 2.

Validation studies of preoperative models

Ref.	Period + number	Sample region	Operation	Characteristics	Source of data	Models tested	Outcomes tested
Zingg et al[42], 2009	1990-2007 (346)	Switzerland/Australia	TT	N: 140/346; H: 259 AC/71 SCC	Two centres	Rotterdam score; Philadelphia score	Mortality
Grotenhuis et al[43], 2010	1991-2008 (777)	Netherlands	TT/TH	N: 221/777; H: N/A	Single centre	Amsterdam score	Morbidity
Bosch et al[44], 2011	1991-2007 (278)	Netherlands	TT	N: 10/278; H: 235 AC/43 SCC	Single centre	ACCI; CCI; O-POSSUM; P-POSSUM	Mortality
Ferguson et al[45], 2011	1980-2009 (514)	United States	TT/TH/hybrid/MIE	N: 167/514; H: 261 AC/137 SCC	Single centre	Amsterdam score	Morbidity + major morbidity
Filip et al[46], 2014	2004-2013 (43)	Romania	TT/TH	N: 22/43; H: 33 SCC/9 AC	Single centre	ACCI; CCI; POSSUM; O-POSSUM; P-POSSUM	Mortality
Yamana et al[47], 2015	2005-2013 (251)	Japan	TT/MIE	N: 150/251; H: N/A	Single centre	GNRI; PNI; E-PASS; POSSUM	Respiratory complications
Lindner et al[48], 2016	2005-2009 (94)	Germany	TT	N: 54/94; H: 94 AC/0 SCC	Single centre	Cologne score	Morbidity
Reinersman et al[49], 2016	2009-2012 (136)	United States	TT/TH/hybrid/MIE	N: 110/136; H: 118 AC/18 SCC	Single centre	Ferguson score	Respiratory complications
Xing et al[50], 2016	2008-2010 (217)	China	TT/TH	N: 0/217; H: 162 SCC/50 AC	Single centre	Ferguson score	Respiratory complications
Takeuchi et al[51], 2018	2000-2016 (438)	Japan	TT	N: 208/438; H: 398 SCC/27 AC	Single centre	Takeuchi model	Mortality
D’Journo et al[52], 2017	2004-2013 (1039)	France	TT/TH	N: 420/1039; H: N/A	National database	Rotterdam score	Mortality
Gray et al[53], 2020	2016-2018 (240)	United States	TT/TH/MIE	N: N/A; H: N/A	Single centre	NSQIP SRC	Morbidity
Peng et al[54], 2020	2012-2019 (218)	United States	MIE	N: 189/218; H: N/A	Single centre	NSQIP SRC	Morbidity + mortality
Ravindran et al[55], 2020	2013-2017 (100)	United States	TT	N: 87/100; H: 75 AC/21 SCC	Single centre	NSQIP SRC	Morbidity + mortality

TT: Transthoracic; TH: Transhiatal; MIE: Minimally invasive esophagectomy; N: Neoadjuvant chemotherapy; H: Histopathology subtype; SCC: Squamous cell carcinoma; AC: Adenocarcinoma; N/A: Not available; NSQIP SRC: National Surgical Quality Improvement Program Surgical Risk Calculator; ACCI: Age-adjusted charlson comorbidity index; CCI: Charlson comorbidty index; POSSUM: Physiological and Operative Severity Score for the Enumeration of Mortality and Morbidity; O-POSSUM: Operative - 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; GNRI: Geriatric nutritional risk index; PNI: Prognostic nutritional index; E-PASS: Estimation of physiologic and surgical stress.