Table 3. Prognostic factors for disease-free survival.

	Unadjusted a		Cox regression, full model b		Cox regression, variable selection c
	HR (95% CI)	P d	HR (95% CI)	P d	HR (95% CI)	P d
C-stage
C-stage 0	Reference	<0.001	Reference	<0.001	Reference	<0.001
C-stage I	2.63 (1.89–3.65)		2.17 (1.51–3.10)		2.08 (1.48–2.94)
Age (years)	1.05 (1.03–1.07)	<0.001	1.04 (1.03–1.06)	<0.001	1.04 (1.03–1.06)	<0.001
Gender
Male	Reference	0.44	Reference	0.435	—
Female	0.88 (0.63–1.23)		0.89 (0.62–1.27)
BMI (kg m−2)	0.95 (0.91–0.99)	0.008	0.96 (0.92–1.00)	0.037	0.96 (0.92–1.00)	0.048
ASA stage
II	Reference	0.002	Reference	0.54	—
III/IV	1.74 (1.23–2.45)		0.92 (0.59–1.41)
Cardiovascular disease
No	Reference	0.006	Reference	0.605	—
Yes	1.75 (1.20–2.56)		1.07 (0.67–1.72)
Chronic obstructive pulmonary disease
No	Reference	0.002	Reference	0.191	—
Yes	2.12 (1.36–3.32)		1.29 (0.78–2.12)
Chronic kidney disease
No	Reference	0.02	Reference	0.137	—
Yes	2.68 (1.27–5.67)		1.83 (0.80–4.19)
AJCC stage
I	Reference		Reference	0	Reference	<0.001
II	1.49 (0.97–2.28)		1.18 (0.75–1.86)		1.26 (0.81–1.96)
III	2.56 (1.74–3.79)		2.15 (1.40–3.31)		2.20 (1.48–3.28)
Distance to anal verge
>10 cm	Reference	0	Reference	0.047	Reference	0.001
>5–10 cm	1.28 (0.82–2.00)		1.86 (1.07–3.23)		1.39 (0.88–2.19)
0–5 cm	2.22 (1.43–3.46)		1.29 (0.80–2.08)		2.19 (1.39–3.45)
Neoadjuvant therapy
No	Reference	0.746	Reference	0.258	—
Yes	0.98 (0.71–1.36)		1.22 (0.83–1.80)
Operation
Anterior resection	Reference	0.003	Reference	0.45	—
Abd. perineal excision	2.00 (1.29–3.11)		1.16 (0.69–1.94)
Operation time (hours)	1.05 (0.92–1.19)	0.437	1.03 (0.90–1.18)	0.551	—
Adjuvant therapy
No	Reference	0.589	Reference	0.587	—
Yes	0.93 (0.66–1.30)		1.07 (0.71–1.60)

Abbreviations: AJCC=American Joint Committee on Cancer; ASA=American Society of Anesthesiologists.

Hazard ratios (HR) with 95% confidence intervals resulting from:

^aUnivariate, Cox proportional hazards regression analysis for disease-free survival;

^bIndependent, full model Cox proportional hazards regression analysis for disease-free survival;

^cIndependent, backward variable selection Cox proportional hazards regression analysis for disease-free survival (confirmed by forward variable selection with identical results);

^dP-values from likelihood ratio tests.