Table 4.

Multivariate analyses evaluating the association between hospital volume and each postoperative outcome recorded for patients undergoing surgery for rectal cancer†

Hospital volume‡	30-day mortality** (n = 51)		P	Severe complications (n = 569)		P
	%	OR (95% c.i.)		%	OR (95% c.i.)
Very high	0.8	1 (ref. cat.)	–	37.7	1 (ref. cat.)
High	1.1	1.18 (0.56–2.49)	0.7	34.5	0.89 (0.66–1.19)	–
Medium	1.6	1.67 (0.89–3.96)	0.09	43.4	1.27 (0.87–1.87)	0.4
Low	2.2	1.21 (0.86–6.43)	0.09	48.7	1.47 (0.90–2.42)	0.2

Hospital volume‡	Removal of ≥ 12 nodes (n = 3042)		P	Non-radical resection (R1/2) (n = 214)		P
	%	OR (95% c.i.)		%	OR (95% c.i.)
Very high	72.3	1 (ref. cat.)	–	5.1	1 (ref. cat.)	–
High	73.3	1.12 (0.93–1.35)	0.2	4.2	0.77 (0.53–1.12)	0.2
Medium	72.9	0.90 (0.71–1.14)	0.4	3.8	0.54 (0.31–0.94)	0.028
Low	63.5	0.57 (0.41–0.80)	0.001	4.4	0.70 (0.34–1.42)	0.3

Hospital volume‡	Neoadjuvant therapy (n = 2331)		P
	%	OR (95% c.i.)
Very high	54.7	1 (ref. cat.)	–
High	44.2	0.66 (0.56–0.77)	<0.001
Medium	43.2	0.75 (0.60–0.92)	0.006
Low	43.4	0.70 (0.52–0.94)	0.019

ref. cat.: reference category. *Hospital procedure volume was defined as the number of surgical procedures performed during the study period (2018–2021). Low-volume hospitals performed between 19 and 111 procedures; medium-volume hospitals performed between 112 and 167 procedures; high-volume hospitals performed between 168 and 263 procedures and very high-volume hospitals performed between 264 and 638 procedures. †All final models were adjusted for age, gender, aggressive biology, AJCC stage, urgent surgery, history of previous colorectal cancer, history of inflammatory bowel disease, presence of other co-morbidities and familial history of colorectal cancer. Severe complications were classified as Clavien–Dindo grade 3 and higher. ‡Due to the scarce number of successes (n = 51), the final model was adjusted for age, gender, AJCC stage, history of previous colorectal cancer.