Application of the Parsonnet scoring system for a Canadian cardiac surgery program

In the past two decades, cases involving patients requiring cardiac surgery have become more complex, presenting with more comorbidities. Outcome analysis has become very important in assessing the quality of cardiac surgical care in these patients. The latest version of the Parsonnet scoring system was developed in 2000 and is the most recent system available.

To evaluate the accuracy of the Parsonnet scoring system in a major Canadian university-based cardiac surgery centre with a population of high-risk patients.

Data on 4883 consecutive patients operated on between 2000 and 2005 were prospectively collected, and a standardized mortality rate was calculated using the Parsonnet score as the ratio of observed deaths to expected deaths. Analyses were conducted on the whole group and on subgroups, based on Parsonnet score distribution quantiles, age and surgery status.

The mean Parsonnet score was 18.8+/-13.7 (range 0 to 83). The overall mortality rate was 6.4%. The overall standardized mortality ratio was 0.52 (95% CI 0.420 to 0.568), which was statistically significant (P=0.01). The observed mortality rate was significantly lower than expected in all categories.

Despite more complex cases with multiple comorbidities, the results of cardiac surgery in a Canadian university hospital show better results than expected when using the Parsonnet score.