Table 4 Sensitivity analyses on NIS sample (Coefficients of opt-out variable)

Main model

39.78

0.0529

1815.3***

0.0840*

(0.62)

(1.08)

(3.76)

(2.43)

 Early opt-out^a vs control

103.9

0.0741

644.5

0.0183

(1.50)

(1.50)

(1.42)

(0.50)

 Late opt-out^b vs control

−185.4

0.0234

2461.0***

0.120*

(−1.14)

(0.29)

(4.42)

(2.38)

 opt-out variable * late opt-out^c

−279.9

−0.0687

2202.9**

0.130*

(−1.87)

(−1.16)

(3.09)

(2.38)

 Removing cases age <18 out of total surgical discharges

39.91

0.0410

1833.5**

0.0784*

(0.61)

(0.98)

(3.41)

(2.28)

 Removing all transplant DRGs and any craniotomy DRGs

38.84

0.0535

1757.2***

0.0831*

(0.61)

(1.09)

(3.75)

(2.39)

 Include only hip and knee surgery procedures

24.12

0.00109

494.1

0.0292

(1.55)

(0.03)

(0.63)

(1.27)

 Exclude hospital characteristics

33.71

0.0477

1839.3***

0.0762*

(0.56)

(1.08)

(4.08)

(2.72)

 Exclude hospital characteristics and county variables

6.887

0.0364

1903.8**

0.0637*

(0.12)

(0.70)

(3.06)

(2.10)

 Exclude hospital variables, county variables and t-1 year variables

−110.4*

−0.0561

1977.9**

0.0709***

(−2.03)

(−1.18)

(2.91)

(4.71)