. Author manuscript; available in PMC: 2016 Jun 6.

Published in final edited form as: Arch Intern Med. 2010 Jul 26;170(14):1202–1208. doi: 10.1001/archinternmed.2010.237

Table 3.

Association between volume, overall quality, and care efficiency

Value	Length of stay			Costs
Value	Unadjusted % difference (95%CI)	Adjusted^* % difference (95% CI)	Adjusted^** % difference (95% CI)	Unadjusted % difference (95%CI)	Adjusted^* % difference	Adjusted^** % difference (95% CI)
Hospital volume
1^st quartile	See Table 2		1.3 (−5.7, 8.8) P=0.7155	See Table 2		18.3 (2.6, 36.5) P=0.0207
2^nd quartile			0.3 (−6.8, 8.0) P=0.9270			−5.4 (−14.5, 15.7) P=0.9437
3^rd quartile			−1.2 (−8.6, 6.8) P=0.7685			0.4 (−14.4, 17.8) P=0.9578
4^th quartile			Referent			Referent
Surgeon volume
1^st quartile	See Table 2		1.2 (−1.0, 3.4) P=0.2838	See Table 2		3.3 (0.8, 5.8) P=0.0104
2^nd quartile			−0.9 (−3.1, 1.5) P=0.4665			1.2 (−1.5, 4.0) P=0.3851
3^rd quartile			0.7 (−1.6, 3.0) P=0.5478			−0.5 (−3.1, 2.3) P=0.7395
4^th quartile			Referent			Referent
Number of missed quality measures
None missed	Referent	Referent	Referent	Referent	Referent	Referent
1 missed	21.5 (19.9, 23.1) P<0.0001	11.9 (10.8, 13.1) P<0.0001	11.9 (10.8, 13.1) P<0.0001	13.7 (12.4, 15.0) P<0.0001	7.8 (6.9, 8.6) P<0.0001	7.8 (6.9, 8.6) P<0.0001
2 missed	12.3 (10.9, 13.7) P<0.0001	8.1 (6.9, 9.3) P<0.0001	8.1 (6.9, 9.3) P<0.0001	5.3 (4.1, 6.4) P<0.0001	6.7 (5.8, 7.6) P<0.0001	6.7 (5.8, 7.6) P<0.0001
3 missed	8.0 (6.7, 9.4) P<0.0001	5.0 (3.8, 6.2) P<0.0001	5.0 (3.8, 6.1) P<0.0001	4.6 (3.5, 5.8) P<0.0001	6.7 (5.8, 7.6) P<0.0001	6.7 (5.8, 7.6) P<0.0001
4 or more	13.0 (11.5, 14.5) P<0.0001	9.5 (8.2, 10.8) P<0.0001	9.5 (8.2, 10.8) P<0.0001	9.6 (8.3, 10.9) P<0.0001	10.1 (9.1, 11.1) P<0.0001	10.1 (9.1, 11.1) P<0.0001

Results of 3 models examining volume and quality measures separately, and adjusting for covariates described in Methods.

^**

Results of single model examining volume measures and quality, and adjusting for covariates described in Methods.