TABLE 4].

Variables Retained by the LASSO Procedures in the Logistic Regression for Predicting Occurrence of PRF

Predictor Variable	Coefficient	Probability Selected, %a
Intercept	−7.4426	100
Anesthesia duration, /h	0.1921	100
Net fluid at end of the operation, /L	0.1681	100
Operations on the cardiovascular system	0.9246	100
Medicare (as the primary payer)	0.4672	100
ASA class ≥ III	0.5663	100
Fio2, median	0.0086	98
Operations on the nervous system	0.5520	96.4
Vasopressor medication in the operating room	0.3000	95.6
Heart rate, median	0.0088	94.8
Tidal volume, median	−0.0011	92.4
Operations on the musculoskeletal system	−0.3957	91.2
Operations on the digestive system	0.1136	88.8
Surgical specialty orthopedic (nonspine)	−0.2202	82.8
Medical (Medicaid) (as the primary payer)	0.1937	82.4
Operations on the urinary system	0.1706	81.2
BMI 30–34.9 kg/m2 (obese 1)	−0.0745	80.4
End-tidal CO2, median	−0.0135	75.6
Race unknown (unable to respond, unavailable or unknown, declined to state)	0.2557	62.8

ASA = American Society of Anesthesiologists; LASSO = least absolute shrinkage and selection operator; PRF = postoperative respiratory failure;

^aProbability selected is the percentage of bootstrap samples in which the variable was retained.