. Author manuscript; available in PMC: 2017 Aug 23.

Published in final edited form as: JAMA Surg. 2017 Jul 19;152(7):e171032. doi: 10.1001/jamasurg.2017.1032

Table 4.

Difference-in-Differences Risk Ratios for ERAS Patient Outcome Metrics After Program Implementation Among Colorectal Resection and Hip Fracture Repair Cohorts^a

Metric	Difference-in-Differences Estimates, Rate Ratio (95% CI)
	Colorectal Resection vs Comparator	P Value	Hip Fracture vs Comparator	P Value
	Hospital length of stay, d	0.92 (0.86–0.99)	.03	0.83 (0.77–0.91)	<.001
Hospital mortality	0.17 (0.03–0.86)	.03	1.12 (0.37–3.41)	.84
Discharge to home	1.01 (0.99–1.02)	.13	1.24 (1.06–1.44)	.007
30-d Readmission	0.94 (0.74–1.20)	.65	0.96 (0.74–1.26)	.78
Postoperative complications	0.68 (0.46–0.99)	.04	0.67 (0.45–0.99)	.05
Major complications	0.28 (0.12–0.68)	.005	0.53 (0.15–1.84)	.32

Abbreviation: ERAS, Enhanced Recovery After Surgery.

A difference-in-differences risk ratio of 0.67 (postoperative complications; hip fracture) can be interpreted as a 33% lower rate of postoperative complications among patients undergoing hip fracture repair after ERAS program implementation compared with before ERAS implementation relative the orthopedics comparator cohort during the same intervals.