Table 3.

Hazard ratios (HR) with 95% confidence intervals (CI) from Cox regressions with shared frailty

	Colon		Rectum
ref: no	HR	CI	HR	CI
Certification only	0.93***	(0.90,0.96)	0.86***	(0.83,0.89)
Certification, age, sex	0.94***	(0.91,0.96)	0.88***	(0.86,0.91)
Certification, age, sex, metastases, secondary malignoma, comorbidities	0.89***	(0.87,0.92)	0.88***	(0.85,0.90)
Certification, age, sex, metastases, secondary malignoma, comorbidities, hospital characteristics	0.88***	(0.86,0.91)	0.88***	(0.85,0.92)
Certification, age, sex, metastases, secondary malignoma, comorbidities, hospital characteristics, calendar year dummies	0.92***	(0.89,0.95)	0.90***	(0.87,0.94)

HR hazard ratio, CI 95% confidence interval, significance levels: *5%, **1%, ***0.1%