Table 2

Methodological validity of included trials

Reference		1 Selection bias				2 Performance bias			3 Attrition bias	4 Detection bias
Reference		Randonisation	Concealed allocation			Blinding intervention	Co-intervention avoided		Centres	<10% withdrawal	Blinding outcome assessment
Froese¹⁶	Not described	Uncertain		No	Yes	1		No	No
HIFI⁶	Computer	Uncertain		No	Yes	11		Yes	Head US2-150
Carlo¹⁷	Envelopes	Uncertain		No	Uncertain	1		Yes	No
Clark⁷	Blind card draw	Uncertain		No	Uncertain	1		Yes	Head US + CXR^†
Ogawa⁸	Envelopes	Uncertain		No	Yes	9		Yes	Head US + CXR
Gerstmann⁹	Blind card draw	Uncertain		No	Uncertain	3		Yes	No
Wiswell²³	Envelopes	Uncertain		No	Uncertain	1		Yes	Head US
Keszler¹⁰	Envelopes	Uncertain		No	No	8		Yes	No
Rettwitz-Volk²⁵	Computer	Uncertain		No	Uncertain	3		Yes	No
Plavka¹¹	Envelopes	Uncertain		No	Uncertain	1		Yes	CXR