RISK STRATIFICATION FOR OPEN-HEART OPERATIONS - COMPARISON OF CENTERSREGARDLESS OF THE INFLUENCE OF THE SURGICAL-TEAM

Background. Risk-adjusted mortality was previously used to compare ins titutions as a whole or surgeons. Because the same surgical team is wo rking in two different hospitals, the aim of our study was to assess w hether the institution can make a difference in surgical mortality. Me thods. Preoperative data of 554 patients in institution A and 500 in i nstitution B were prospectively collected during the same period of ti me. All patients were operated on by the same surgeon with the same fi rst assistant and anesthesiology staff in both institutions. Patient p opulation was stratified according to Parsonnet's predictive model, in five risk groups, and mortality was adjusted by the direct standardiz ation method. Results. At institution A it was observed that in-hospit al mortality was 2.3% (95% confidence interval, 1.3% to 4.0%), and in institution B 4.0% (95% confidence interval, 2.5% to 6.1%). The differ ence between the two mortality rates (1.7%; 95% confidence interval, - 0.5% to 3.8%) is not statistically significant (p = 0.16), nor is the difference within each class. The standardized mortality ratio was 3.6 % (95% confidence interval, 2.7% to 4.8%) and 5.8% (95% confidence int erval, 4.6% to 7.2%), respectively. The difference of 2.2% (95% confid ence interval, 0.5% to 3.8%) is statistically significant (p = 0.01). Conclusions. The institution can affect mortality of patients undergoi ng open heart operations, regardless of the influence of the surgical team. (C) 1997 by The Society of Thoracic Surgeons.