Table 3 Methodological quality of included trials.

Study	Allocation concealment	Method of randomisation	Blinded assessment of outcome	Description of withdrawals	Intention to treat analysis
MRC, UK25	Adequate	Not reported	None described	No description	Yes*
NCI, USA27	Adequate	Not reported	None described	Yes	Yes
National Cancer Institute of Canada trial, North America26	Adequate†	Adequate†	No	No losses†	Yes†
RTOG‡ 89–0117	Not reported	Not reported	None described	Incomplete description	No
University of Athens, Greece16	Not reported	Not reported	None described	No description	No
Intergroup 0139 trial (RTOG‡ 93–09), North America20	Not reported	Not reported	None described	Incomplete description	No
Yamaguchi University (VATS v open)24	Inadequate	Inadequate	None described	No losses†	No
Lung Cancer Study Group trial, North America22	Adequate	Not reported	None described	Yes (N.B. 18% loss in each group)	Unclear
University of Munich13	Adequate†	Adequate	Yes§	Yes	No
Yamaguchi University14	Adequate†	Adequate	None described	Yes	Yes
Sun Yat‐Sen University of Medical Sciences, Guangzhou15	Adequate†	Adequate†	None described	Yes	No

*Unclear if losses to follow up.

†Confirmed by contacting authors.

‡RTOG, Radiation Therapy Oncology Group.

§Investigators undertaking follow up blinded from treatment group.