Table 2.

 Overview and meta-analysis of randomised controlled trials on impact of flexible sigmoidoscopy: results on colorectal cancer incidence and mortality. Values are relative risks (95% confidence intervals) unless stated otherwise

Type of analysis and studies	Incidence				Mortality
	Any site	Proximal	Distal		Any site	Proximal	Distal
Intention to screen:
Hoff et al 200912	1.02 (0.83 to 1.25)*	NR	NR		0.73 (0.47 to 1.13)	NR	0.63 (0.34 to 1.18)
Atkin et al 201013	0.77 (0.70 to 0.84)	0.98 (0.85 to 1.12)	0.64 (0.57 to 0.72)		0.69 (0.59 to 0.82)	NR	NR
Segnan et al 201114	0.82 (0.69 to 0.96)	0.91 (0.69 to 1.20)	0.76 (0.62 to 0.94)		0.78 (0.56 to 1.08)	0.85 (0.52 to 1.39)	0.73 (0.47 to 1.12)
Schoen et al 201215	0.79 (0.72 to 0.85)	0.86 (0.76 to 0.97)	0.71 (0.64 to 0.80)		0.74 (0.63 to 0.87)	0.97 (0.77 to 1.22)	0.50 (0.38 to 0.64)
Meta-analysis:
No of studies	4	3	3		4	2	3
Pooled estimate	0.82 (0.75 to 0.89)	0.91 (0.83 to 0.99)	0.69 (0.63 to 0.74)		0.72 (0.65 to 0.80)	0.95 (0.77 to 1.17)	0.54 (0.43 to 0.67)
Heterogeneity: I2 (%)/τ2/P value	52/0.004/0.10	0/0.0/0.38	24/0.002/0.27		0/0.0/0.90	0/0.0/0.63	0/0.0/0.52
Per protocol†:
Hoff et al 200912	0.89 (0.69 to 1.15)*	NR	0.73 (0.51 to 1.05)*		0.41 (0.21 to 0.82)	NR	0.24 (0.08 to 0.76)
Atkin et al 201013	0.67 (0.60 to 0.76)	0.97 (0.80 to 1.17)	0.50 (0.42 to 0.59)		0.57 (0.45 to 0.72)	NR	NR
Segnan et al 201114	0.69 (0.56 to 0.86)	0.85 (0.61 to 1.19)	0.60 (0.46 to 0.80)		0.62 (0.40 to 0.96)	0.78 (0.45 to 1.35)	0.48 (0.24 to 0.94)
Schoen et al 201215	NR	NR	NR		NR	NR	NR
Meta-analysis:
No of studies	3	2	3		3	1	2
Pooled estimate	0.72 (0.62 to 0.84)	0.94 (0.80 to 1.11)	0.58 (0.47 to 0.71)		0.56 (0.46 to 0.69)	0.78 (0.45 to 1.35)	0.39 (0.21 to 0.73)
Heterogeneity: I2 (%)/τ2/P value	49/0.002/0.14	0/0.0/0.50	49/0.02/0.14		0/0.0/0.60	–/–/1.00	6/0.02/0.30

NR=not reported.

P values are based on Cochran’s Q statistic.

*Not reported directly by authors but derived from reported data.

†Adjusted for non-adherence but not for contamination.