. 2019 Jan 16;154(5):391–400. doi: 10.1001/jamasurg.2018.5242

Table 3. Multivariable Linear Regression Model to Predict RSRRs.

Characteristic	Estimate (95% CI)	P Value
Safety net	1.02 (0.75-1.29)	<.001^a
Year
2011	1 [Reference]	NA
2012	0.35 (0.10-0.61)	.007^a
2013	0.48 (0.23-0.74)	<.001^a
2014	−0.06 (−0.32 to 0.20)	.64
State
Florida	2.64 (2.10-3.19)	<.001^a
New York	1.44 (0.89-1.99)	<.001^a
Iowa	1 [Reference]	NA
Washington	0.04 (−0.50 to 0.56)	.88
Teaching status
Yes	0.49 (0.22-0.76)	<.001^a
No	1 [Reference]	NA
Size, No. of beds
<200	−0.33 (−0.67 to 0.00)	.05
200-299	1 [Reference]	NA
300-499	−0.14 (−0.46 to 0.18)	.40
500+	−0.33 (−0.74 to 0.08)	.11
Ownership
Nonfederal government	1 [Reference]	NA
Not-for-profit private	−0.61 (−0.87 to −0.35)	<.001^a
For-profit private	0.65 (0.25-1.05)	.002^a
Location
Metropolitan	1 [Reference]	NA
Micropolitan	−0.23 (−0.80 to 0.35)	.44
Rural	−0.48 (−1.98 to 1.01)	.52
Ambulatory surgery center^b
Yes	−0.49 (−0.72 to −0.27)	<.001^a
No	1 [Reference]	NA
Cardiac intervention capability^b
Cardiac surgery	1 [Reference]	NA
Cardiac catheterization	−0.59 (−0.90 to −0.28)	<.001^a
Neither	−0.30 (−0.66 to 0.06)	.10
Nurse staffing ratio quartile
First	1 [Reference]	NA
Second	−0.42 (−0.71 to −0.14)	.004^a
Third	−0.41 (−0.70 to −0.12)	.006^a
Fourth	0.10 (−0.24 to 0.43)	.57
Surgery volume^c	−0.48 (−0.65 to −0.30)	<.001^a

Abbreviations: NA, not applicable; RSRR, risk-standardized readmission rate.

^{^a}

Significance defined as P < .05 using paired, 2-tailed t tests.

^{^b}

A total of 402 hospitals had missing values on ambulatory surgery center and/or availability of cardiac procedures. We set the missing values as an additional category for each of these 2 variables to keep these observations in the model.

^{^c}

Used as a continuous variable with no reference group.