Table 2.

Multiple regression analysis of author, trial and journal characteristics associated with the reporting quality of RCT protocols

	Increase in proportion of adequately reported checklist items from the SPIRIT statement	P value
Author characteristics
Number of authors per protocol	0.2%	0.004
One or more authors with expertise or experience in epidemiology or statistics	2.6%	0.016
Trial characteristics
Multicentre status	4.6%	0.000
Protocol word length >3500	6.5%	0.000
Protocols self-reporting compliance with the SPIRIT statement	–	0.145
Journal characteristics
Journal policy of compliance with the SPIRIT statement	6.2%	0.000

RCT, randomised controlled trial; SPIRIT, Standard Protocol Items: Recommendations for Interventional Trials.