Supplemental Digital Content: Table. Variables included in multivariate logistic
regression complex readmission model. Nonlinear relationships seen for continuous
variables were modeled with spline terms.
Variable
Age
Gender
BMI
Race
ASA Class
Admission status
Incoming transfer status
Urgency
Current smoker
Dyspnea
Ventilator dependence
COPD
Ascites
CHF
Hypertension
Acute kidney injury
Dialysis
Diabetes
Functional status
Disseminated cancer
Unintended weight loss
Wound infection
Corticosteroids
Bleeding disorder or
anticoagulation
Preoperative transfusion
Sepsis
Albumin
Operation time
Relative value units
Wound class
Inpatient complications
Length of stay
Discharge destination
Type
Continuous
Binary
Linear spline with knots at 18.5 and 25
Categorical (non-Hispanic white, black, Hispanic, Asian, American
Indian or Alaska Native, Native Hawaiian or Pacific Islander,
unknown)
Categorical (1-5)
Binary (inpatient, outpatient)
Categorical (not transferred, long term care, acute rehabilitation,
outside emergency department, outside hospital)
Binary variables for emergent and non-elective operations
Binary
Categorical (none, at rest, with exertion)
Binary
Binary
Binary
Binary
Binary
Binary
Binary
Categorical (none, non-insulin, insulin)
Categorical (normal, partial vs. total impairment)
Binary
Binary
Binary
Binary
Binary
Binary
Categorical (none, SIRS, sepsis, septic shock)
Categorical (bins every 0.5 g/dL and missing)
Continuous
Linear spline with knot at 10
Categorical (I-IV)
Binary variables for superficial, deep, or organ space SSI, dehiscence,
pneumonia, reintubation, extended ventilator dependence, acute
kidney injury, dialysis, urinary tract infection, stroke, coma,
peripheral nerve injury, cardiac arrest, myocardial infarction,
transfusion, pulmonary embolism, deep venous thrombosis, sepsis,
and septic shock
Categorical (by day)
Categorical (home, rehabilitation, long term care)
BMI: Body Mass Index, ASA: American Society of Anesthesiologists, COPD: Chronic Obstructive
Pulmonary Disorder, CHF: Congestive Heart Failure, SIRS: Systemic Immune Response Syndrome