Minimum sample size estimates for trials in inflammatory bowel disease: A systematic review of a support resource

Table 1 Overall summary of power calculations and sample size deficits

	Total studies	Studies with power calculation	Studies with difference of 10% and less1	How many studies didn’t achieve target sample size	Mean sample size underpowered (range)	Mean sample size needed	How many studies are underpowered2
CD induction	39	26	12	6	28 (2-70)	231	11
CD maintenance	25	19	9	3	52 (7-79)	300	10
UC induction	27	19	8	3	22 (1-55)	219	4
UC maintenance	16	10	0	1 + 1 didn’t report	21	196	7

¹Those studies were not included in analysis.

²Either didn’t achieve their target sample size, or their achieved sample size is less than mean sample size needed.

UC: Ulcerative colitis; CD: Crohn’s disease.