. Author manuscript; available in PMC: 2018 Mar 14.

Published in final edited form as: N Engl J Med. 2017 Sep 14;377(11):1055–1064. doi: 10.1056/NEJMsa1702321

Table 2.

Difference in observed 30-day readmission rate (%) and 95% confidence interval and number of admissions of each quartile pair.

Quartile pairs	Number of pairs	Observed 30-day readmission rate, %		Difference in readmission rate, %	95% confidence interval, %

		Lower quartile	Higher quartile
Q12	5649	21.26	21.65	0.39	(−1.53, 2.31)
Q23	3472	23.10	23.85	0.75	(−1.81, 3.30)
Q34	8049	25.78	25.98	0.20	(−1.51, 1.91)
Q13	5781	23.11	23.53	0.42	(−1.56, 2.39)
Q24	6035	24.09	25.34	1.25	(−0.71, 3.20)
Q14	9355	23.13	25.08	1.95	(0.39, 3.50)

Lower quartile and higher quartile represent the 2 groups of each quartile pair; Q, quartile-pair (e.g., Q12, quartile-pair comparison Q1 vs. Q2); the confidence interval for the difference in observed 30-day readmission rate is calculated using McNemar’s test with Bonferroni adjustment (statistical significance level was 0.05/6=0.0083).