Objective: Monitoring health outcomes across hospitals has become a growing interest as a potential means to promote quality of care, but in Italy it is at the beginning stage. We aimed at comparing the performance of different cardiac surgery units and testing the utility of routinely collected data in this respect.
Methods: From the Lazio region hospital information system (HIS), we selected a cohort of 1603 individuals (84% males; mean age 63 years, SD 8) residing in Rome (2,685,890 inhabitants), who underwent isolated coronary artery bypass surgery (CABG, ICD-9-CM code: 36.1) in the period 1996-97 in seven major cardiac surgery units in the city. They were identified as A, B, C (teaching), D and E (non-teaching) units. Information on vital status at 30 days after the CABG surgery was obtained through an automatic record linkage with the Municipal Registry of Rome. The association between cardiac surgery units and outcome was evaluated through logistic regression taking into account the following a priori risk factors in different models: gender, age, socio-economic status, type of ischaemic heart disease and comorbidities.
Results: The overall mortality was 5.4% (range 2.1-11.4%). Statistically significant predictors of outcome included: age (OR=7.5 for age> or =70 vs. 35-49 years), acute myocardial infarction (OR=32.7 vs. acute-subacute forms/angina), chronic myocardial ischaemia (OR=4.2 vs. acute-subacute forms/angina), other heart diseases (OR=4.8), chronic renal disease (OR=16.0) and peripheral arterial disease (OR=2.9). Statistically significant variability in mortality was observed across hospitals; taking hospital A as reference, hospital D showed the highest risk (OR=5.7, 95% CI=1.9-17.3, in the fully adjusted model).
Conclusions: We suggest that a true variation in quality of care play a role in the observed differences across hospitals, although chance and inaccurately measured risk factors cannot be excluded. Despite some limitations, the HIS is a valid tool for screening cardiac surgery units with poor performance.