Clinical research study
Perioperative cardiovascular mortality in noncardiac surgery: Validation of the Lee cardiac risk index

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Abstract

Purpose

The Lee risk index was developed to predict major cardiac complications in noncardiac surgery. We retrospectively evaluated its ability to predict cardiovascular death in the large cohort of patients who recently underwent noncardiac surgery in our institution.

Methods

The administrative database of the Erasmus MC, Rotterdam, The Netherlands, contains information on 108 593 noncardiac surgical procedures performed from 1991 to 2000. The Lee index assigns 1 point to each of the following characteristics: high-risk surgery, ischemic heart disease, heart failure, cerebrovascular disease, renal insufficiency, and diabetes mellitus. We retrospectively used available information in our database to adapt the Lee index calculated the adapted index for each procedure, and analyzed its relation to cardiovascular death.

Results

A total of 1877 patients (1.7%) died perioperatively, including 543 (0.5%) classified as cardiovascular death. The cardiovascular death rates were 0.3% (255/75 352) for Lee Class 1, 0.7% (196/28 892) for Class 2, 1.7% (57/3380) for Class 3, and 3.6% (35/969) for Class 4. The corresponding odds ratios were 1 (reference), 2.0, 5.1, and 11.0, with no overlap for the 95% confidence interval of each class. The C statistic for the prediction of cardiovascular mortality using the Lee index was 0.63. If age and more detailed information regarding the type of surgery was retrospectively added, the C statistic in this exploratory analysis improved to 0.85.

Conclusion

The adapted Lee index was predictive of cardiovascular mortality in our administrative database, but its simple classification of surgical procedures as high-risk versus not high-risk seems suboptimal. Nevertheless, if the goal is to compare outcomes across hospitals or regions using administrative data, the use of the adapted Lee index, as augmented by age and more detailed classification of type of surgery, is a promising option worthy of prospective testing.

Section snippets

Hospital setting, procedures and patients

The Erasmus Medical Center, a metropolitan university hospital that serves a population of approximately 3 million people in the southwestern area of The Netherlands, acts as a tertiary referral center for approximately 30 affiliated hospitals. Between January 1, 1991, and December 31, 2000, 122 860 noncardiac surgical procedures were performed in patients above the age of 15 years in the Erasmus Medical Center. We excluded 14 267 planned and unplanned procedures that were conducted within 30

Results

A total of 52 387 surgical procedures were performed in men, including 12 378 orthopedic surgeries (24%); 9273 ear, nose, and throat surgeries (18%); and 8637 abdominal surgeries (16%). Among the 56 206 procedures in women, gynecological surgery was most common with 15 312 procedures (27%), followed by orthopedic surgery with 9840 (18%), and abdominal surgery with 7816 (14%). Because of reallocation of patients among regional hospitals, the annual volumes of ophthalmic and gynecological procedures

Discussion

Cardiovascular mortality still is a major burden in patients undergoing noncardiac surgery. In the investigated cohort, about 7 of every 1000 procedures in men and 3 of every 1000 procedures in women resulted in fatal in-hospital cardiovascular complications. In contrast, anesthesia-related mortality occurs only in approximately 1 of 250 000 procedures.16 Interestingly, patients who underwent postmortem examination were considerably more often classified as cardiovascular death than were

Conclusion

This single center study, which involved over 100 000 subjects, demonstrated that perioperative cardiovascular mortality is a major burden in patients undergoing noncardiac surgery. Little progress has been achieved in reducing cardiovascular mortality during the years of the study. The adapted Lee index had an admirable performance to predict cardiovascular mortality, but its simple classification of procedures as high risk versus not high risk seems suboptimal. Our analysis is limited by the

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