Table 3. Multivariate logistical regression analysis reporting the adjusted odds of each outcome.

Variables	In-hospital mortality			Abdominoperineal resection			Length of stay			30-day readmission
	OR	IC 95%		OR	IC 95%		OR	IC 95%		OR	IC 95%
Volume (procedures/year)
High (32+)	1.00			1.00			1.00			1.00
Medium (13 - 31)	1.41	1.17	1.70	1.16	1.07	1.26	1.54	1.37	1.74	1.09	1.00	1.18
Low (1 - 12)	1.49	1.25	1.78	1.49	1.38	1.61	2.29	2.05	2.55	1.10	1.02	1.19
Age categories (years)
18-49	1.00			1.00			1.00			1.00
50-59	4.93	1.78	13.62	1.06	0.95	1.17	1.05	0.97	1.13	0.90	0.79	1.03
60-69	6.53	2.42	17.67	1.14	1.04	1.26	1.23	1.15	1.33	0.95	0.84	1.08
70-79	15.31	5.70	41.08	1.46	1.32	1.60	1.70	1.58	1.83	1.00	0.88	1.13
80+	30.47	11.33	81.92	1.68	1.51	1.86	2.31	2.12	2.50	1.21	1.05	1.38
Gender
Male	1.00			1.00			1.00			1.00
Female	0.66	0.57	0.76	1.01	0.97	1.06	0.89	0.86	0.92	0.79	0.75	0.84
Hospitalization in the year prior to the index surgery
0	1.00			1.00			1.00			1.00
1	1.12	0.96	1.31	1.48	1.41	1.55	1.16	1.11	1.21	1.20	1.12	1.29
>1	1.39	1.15	1.69	2.00	1.87	2.13	1.32	1.25	1.40	1.27	1.16	1.40
Abdominal surgery in the 3 years prior to the index surgery
No	1.00			1.00			1.00			1.00
Yes	1.47	1.20	1.80	0.87	0.80	0.95	1.02	0.95	1.10	1.10	0.98	1.23
Charlson score
0	1.00			1.00			1.00			1.00
1 - 2	1.43	1.23	1.67	0.98	0.92	1.03	1.27	1.21	1.33	1.29	1.20	1.39
3+	3.60	2.80	4.63	0.85	0.73	0.98	1.62	1.43	1.84	1.82	1.54	2.16
Year of index Hospitalization
2002 - 2006	1.00			1.00			1.00			1.00
2007 - 2010	0.80	0.68	0.94	0.83	0.78	0.89	0.61	0.56	0.66	1.15	1.06	1.24
2011 - 2014	0.71	0.60	0.84	0.85	0.80	0.91	0.40	0.37	0.43	1.34	1.24	1.45
Stoma creation during the index hospitalization
No	1.00			1.00			1.00			1.00
Yes	1.04	0.91	1.19	0.72	0.69	0.76	1.53	1.47	1.58	1.62	1.53	1.72
Surgical approach
Open	1.00			1.00			1.00			1.00
Laparoscopy	0.47	0.38	0.59	0.71	0.67	0.76	0.54	0.51	0.56	1.07	1.00	1.15