2. Summary of quality.

Study	Inclusion criteria similar for IPD‐MA and AD‐MA?	Study quality*	Comparison of IPD‐MA and AD‐MA a main aim of the study?	IPD‐MA and AD‐MA done by independent researchers?	Same outcome definitions for IPD‐MA and AD‐MA?
Berlin 2002	Yes	A	Yes	No	Yes
Best 2000	Yes	A	Yes	No	Yes
Beveridge 2015	Yes	A	No	No	Yes
Brouwer 2009	Yes	B (Insufficient information)	No	No	Yes
Clarke 1998	Yes	A	Yes	No	Yes
D'Amico 1998	Yes	A	Yes	No	Yes
Duchateau 2001	Yes	A	Yes	No	Yes
Fortin 1995	Yes	A	Yes	No	Yes
Franzosi 1997	Unclear	B (Insufficient information)	Yes	Unclear	Unclear
Ioannidis 1999	Yes	A	No	Yes	Yes
Jeng 1995	Yes	A	Yes	No	Yes
Jones 2009	Yes	A	Yes	No	Yes
Kim 2010	Yes	A	No	No	Yes
Koopman 2008	Yes	A	Yes	Yes	Yes
le Chevalier 1996	Yes	B (Statistical methods unclear)	Yes	Yes	Yes
Legg 2003	Unclear	B (Insufficient information)	Yes	Yes	Unclear
Lindley 2005	Yes	A	No	No	Yes
Lukka 2006	Yes	B (Statistical methods unclear)	No	Yes	Yes
Michiels 2005	Yes	A	Yes	No	Yes
Myeloma 1998	Yes	A	No	Unclear	Yes
Pignon 1992	Yes	A	Yes	Yes	Yes
Rejnmark 2012	Yes	A	No	Yes	Yes
Rothwell 2011	Yes	A	No	No	Yes
Saillourglenisson 2000	Yes	A	No	No	Yes
Schmid 2004	Yes	A	Yes	No	Yes
Shepperd 2009	Yes	A	No	No	Yes
Spooner 1998	Yes	B (Insufficient information)	Yes	Yes	Yes
Stewart 1993	Yes	A	Yes	Unclear	Yes
Szczech 1998	Yes	A	No	No	Yes
Teramukai 2004	Yes	A	Yes	No	Yes
Thompson 2001	Yes	A	Yes	Yes	Yes
Tierney 2001	Yes	B (Insufficient information)	Yes	Yes	Yes
Tonia 2011	No	B (Insufficient information)	No	Yes	No
Tudur 2001	Yes	A	No	No	Yes
Tudur Smith 2005	Yes	A	Yes	No	Yes
Turner 2000	Yes	A	Yes	No	Yes
Vansteenkiste 2012	Yes	B (Insufficient information)	No	No	Yes
Walwyn 2015	Yes	B (Insufficient information)	No	No	Yes
Williamson 2000	Yes	A	No	Yes	Yes

* A = No important flaws; B = Possibly important flaws; C = Major flaws

Abbreviations: AD: Aggregate data, AD‐MA: Aggregate data meta‐analysis, IPD: Individual participant data, IPD‐MA: Individual participant data meta‐analysis