Evaluation of the relationship between preoperative risk scores, postoperative and total length of stays and hospital costs in coronary bypass surgery.

Objectives: Several risk indices have been developed for the prediction of postoperative mortality and morbidity in coronary artery bypass operations, in which the risk scores are currently recorded as routine praxis. The aim of the present study was to determine whether the risk scores can be used to predict the hospital (LOS) and postoperative (POS) lengths of stay and total costs among coronary artery bypass graft (CABG) patients.

Methods: All first-time CABG patients (n=2104) treated at Helsinki University Central Hospital during 1997-1998 were preoperatively scored using the Cleveland Clinic preoperative model. A multivariate analysis was used to evaluate the effects of the risk scores on the LOS and POS and total costs.

Results: The mean preoperative risk score for the patients was 1.69. The increase in preoperative risk score was associated with an increase in the LOS (0.8 days by point), and POS (with 0.55 days by point). An age over 74 years increased the LOS by an extra day. The mean total cost for the CABG procedure was 8750 euros (SD 4430 euros). The costs increased as the risk score increased. Compared with the zero risk score, a score value of 2 was associated with a 1300 euros increase in total cost and a score value of over 6 was associated with an over 7000 euros cost increase. On average, the costs increased by 6980 euros (80%) for one major complication and by 935 euros (10%) in the elderly (>74 years of age).

Conclusions: The results show that increasing risk scores were associated with longer postoperative hospital lengths of stay (POS and LOS) and with increased total costs. An age over 74 years appears to be an independent risk factor in increased POS, LOS and total cost. These results may help to estimate the impact of the preoperative risk profile on the resource requirement in CABG surgery.