Strobe checklist

1	Title and abstract	title has study design in it
structured abstract gives summary	
2	Background / rationale	introduction gives summary of the background to ClinicalTrials.gov and the motivation for the current study	
3	Objectives	under heading ‘Aims’.  Both of the study objectives are were pre-determined prior to obtaining the data	
4	Study design	under heading ‘Study design and setting’.  	
5	Setting	under heading ‘Study design and setting’. 	
6	Participants	under heading ‘Study design and setting’.	
7	Variables	under heading ‘Methods’	
8	Data source / measurement	under heading ‘Methods’.  See also supplementary file 3 for a full list of variables and their sources.  	
9	Bias	Sources of bias are discussed in the discussion (in ‘Strengths and Limitations’)	
10	Study size	Study was of all the trials which should have reported results.  We did not take a sample.  	
11	Quantitative variables	No quantitative variables.
Study variables were essentially categorical (e.g. results reported / results not reported).    	
12	Statistical methods	Methods used to describe the dataset (i.e. proportion of trials with results) is described in the methods. An R script reproduces the methods completely.  	
13	Participants	Figure 1 gives participation of the studies in a flow diagram	
14	Descriptive data	1st paragraph of the results gives the study characteristics and describes missing data	
15	Outcome data	See results	
16	Main results	Figure 1 gives the main results	
17	Other analyses	Results section paragraphs 2 and onwards	
18	Key results	Discussion section paragraph 1	
19	Limitations	Discussion section ‘Strengths and limitations’	
20	Interpretation	See conclusion	
21	Generalisability	We discuss that in the future reporting may improve (thus our findings may not be generalisable to future cohorts of studies) in the discussion ‘Strengths and limitations’	
22	Funding	See acknowledgements statement