Determining external randomised pilot trial feasibility in preparation for a definitive trial: a web-based survey of corresponding authors of external pilot trial publications

Table 1 Survey outlines included in the original sample (identified from previous methodological review) and final sample (following literature search for corresponding result publications)

Survey number	Progression criteria^a	Publication type	Original sample	Final sample	Response rate
Survey 1	Yes	Protocol	123	55	19/55 (34%)
Survey 2	Yes	Results	37	108	41/108 (37%)
Survey 3	No	Protocol	84	41	8/41 (19%)
Survey 4	No	Results	34	72	30/72 (41%)
Total^b	-	-	278	276	98/276 (36%)

^aNo: Did not report detailed progression criteria but did report prespecified targets relating to recruitment or sample size
^bThere were two instances where the protocol and results publications for the same external pilot trial were included in the original sample: since both relate to the same pilot trial, only the result publication was included in the final sample

ISSN: 1745-6215