Ecker 2015.

Methods	Study design: retrospective cohort study
Participants	Country: USA. Number eligible: 73. Post‐randomisation drop‐outs: 0 (0%). Number analysed: 73. Average age: 64 years. Females: 16 (21.9%). Stage I: 13(17.8%). Stage II: 19 (26%). Stage III: 31 (42.5%). Stage IV: not stated Squamous cell carcinoma: 4 (5.5%). Adenocarcinoma: 68 (93.2%). Study design: Retrospective cohort study with contemporary controls Total follow‐up in months: median:10 months ASA: not stated Location: not stated Inclusion criteria Patients undergoing transhiatal oesophagectomy
Interventions	Group 1: laparoscopic transhiatal oesophagectomy (N = 36). Further details: number of ports ‐ not stated; minilaparotomy incision size ‐ not stated; drain use ‐ not stated. Group 2: open transhiatal oesophagectomy (N = 37). Further details: incision size ‐ not stated; drain use ‐ not stated.
Outcomes	The outcomes reported were short‐term and long‐term mortality, oesophageal stenosis, short‐term recurrence, blood transfusion, length of hospital stay, positive resection margin, and number of lymph nodes harvested.
Notes	Proportion of people with cancer: 96% to 99% (error in the number of patients with different aetiologies) Conversion: 4/36 (11.1%)
Risk of bias
Bias	Authors' judgement	Support for judgement
Bias due to confounding	Unclear risk	No information Comment: There was no evidence of baseline differences between the groups. However, the sample size was not sufficient to identify baseline differences. In addition, not all confounding factors were listed in the baseline differences table (for example, no information was presented on the differences in the size of the tumours)
Bias due to selection of participants to intervention and control	Unclear risk	No information Comment: Method of selection of participants to intervention and control was not reported.
Bias due to differences in co‐interventions which were different between the groups	Unclear risk	No information Comment: It was not clear there were other differences in care of the patient apart from the intervention and control.
Bias in the measurement of outcomes	Unclear risk	No information Comment: Information on observer blinding was not available.
Bias due to missing data	Low risk	Low risk of bias Comment: All patients were included in the analysis.
Bias in selection of the reported findings	High risk	Serious risk of bias Comment: Morbidity was not reported.