Table 4.

Standardized incidence ratios for colorectal cancers in patients with a first-time hospital-based diagnosis of constipation, by presence/absence of a lower endoscopy performed in the period from 3 months prior to 4 weeks following the constipation diagnosis, Denmark, 1978–2013

	Colorectal cancers diagnosed ≥4 weeks – 1 year from constipation diagnosisa			Colorectal cancers diagnosed ≥1 year from constipation diagnosis
	O	E	SIR (95% CI)	O	E	SIR (95% CI)
Endoscopy (N=24,194)	112	38.8	2.9 (2.4–3.5)	121	185.3	0.7 (0.5–0.8)
No Endoscopy (N=144,751)	451	168.0	2.7 (2.4–2.9)	734	837.3	0.9 (0.8–0.9)

Note: ^aFollow-up was initiated 4 weeks after the constipation diagnosis because the analysis was conditioned on lower endoscopy up until 4 weeks after the constipation diagnosis.

Abbreviations: CI, confidence interval; E, expected number of cases; O, observed number of cases; SIR, standardized incidence ratio.