Figure 2. A decision-analysis model to compare a strategy of outpatient surgery with routine overnight admission to a ward compared with outpatient surgery and discharge to home if patients meet established criteria. For the discharge-home strategy, the model assumes that two thirds of complications could be treated at home by a home healthcare nurse, whereas the remainder of the patients in whom a complication develops require an emergency room visit and possible admission (see text). The probabilities for each of the nodes are listed in the box, and are based on the rates observed in the current series. Using the baseline values listed in the tree (base-case scenario), the optimal strategy would be outpatient surgery with discharge to home. #Complimentary probability for a given node; i.e., 1 - probability of the complimentary node; cER = cost of an emergency room visit; CHHC = cost of a home healthcare visit; cInpatient = cost of an overnight admission based on the Medicare per diem rate; cOutpatient = cost of surgery on an outpatient basis; pAdmission = probability of direct admission after surgery; pAdmission2 = probability of readmission after discharge; pComplications = probability of development of complications at home.