Study	Reason for exclusion
Chan 2004A	Assessed factors influencing publication of outcomes in randomised trials approved by the Scientific Committees for Copenhagen and Frederiksberg, Denmark (1994 ‐1995). Data for positive and negative findings were available only for published trials.
Chan 2004B	Assessed factors influencing publication of outcomes in randomised trials approved by the Canadian Institutes of Health (1990 ‐1998). Data for positive and negative findings were available only for published trials.
Cronin 2004	Assessed factors influencing publication of outcomes in 101 research studies commissioned by the North Thames Region of the NHS R & D Programme in the UK (1993 ‐1998). Data were not available separately for reports of clinical trials. The analysis of proportion published was also not available for positive and negative/null findings.
Decullier 2005	Assessed factors influencing publication in 649 research protocols approved by French Research Ethics Committee (1994). Data were not available separately for reports of clinical trials.
Easterbrook 1991	Assessed factors influencing publication in 285 studies approved by the Central Oxford Research Ethics Committee (1984 ‐1987). Data were not available separately for reports of clinical trials.
Hahn 2002	Assessed factors influencing publication of protocols of studies approved by a local ethics committee. This study did not assess the rate of publication for positive and negative findings.
Melander 2003	Assessed factors influencing publication of 42 clinical trials of selective serotonin reuptake inhibitors approved by the Swedish Drug Regulatory Authority (1989 ‐1994). Not all trials were registered prior to the main results becoming known.
Misakian 1998	Assessed factors influencing publication in 84 studies of the effects of passive smoking which were identified through organisations known to fund such research (1981‐1995). Data were not available for reports of clinical trials.
Pich 2003	Assessed factors influencing publication in 166 clinical trials submitted to the Hospital Clinic Ethics Committee, Spain (1997). This study did not assess the rate of publication for positive and negative findings.
Wormald 1997	Assessed factors influencing publication in 68 clinical trials registered with the pharmacy of Moorfields Eye Hospital, London (1963 ‐1993). Data were not available for the rate of publication for positive and negative findings.