Analysis of deaths while waiting for cardiac surgery among 29,293 consecutive patients in Ontario, Canada. The Steering Committee of the Cardiac Care Network of Ontario

Abstract

Objectives: To assess death rates among patients waiting for cardiac valve surgery or isolated coronary artery bypass surgery (CABG), and to determine independent risk factors for death while waiting for isolated CABG.

Design: Prospective cohort analysis based on an inclusive registry.

Setting: Nine cardiac surgical units in Ontario, Canada.

Patients: 29,293 consecutive patients scheduled for cardiac surgery between October 1991 and June 1995.

Main outcome measures: Death rates while waiting for surgery were determined among patients scheduled for isolated CABG, isolated valve surgery, or combined procedures. Predictors of death among patients with isolated CABG were determined from multivariate analysis.

Results: There were 141 deaths (0.48%) among 29,293 patients. Adjusting for age, sex, and waiting time, patients waiting for valve surgery had a significantly increased risk of death compared with patients waiting for CABG alone (adjusted odds ratio 1.88, 95% confidence interval (CI) 1.23 to 2.88, p = 0.004). Results were similar for patients waiting for combined valve and CABG procedures compared with those who were waiting for isolated CABG. Independent risk factors for death while waiting for isolated CABG included: impaired left ventricular function (odds ratio 2.47, 95% CI 1.59 to 3.84, p < 0.001); advancing age (for each decade, odds ratio 1.41, 95% CI 1.10 to 1.80, p = 0.007); male sex (odds ratio 1.95, 95% CI 1.00 to 3.81, p = 0.05); and waiting longer than the maximum time recommended in Canadian guidelines for a patient's clinical profile (odds ratio 1.59, 95% CI 1.01 to 2.51, p = 0.044). After scaling waiting time to surgery or death continuously in days, the same predictors emerged.

Conclusions: Patients waiting for valve surgery have a higher risk of death than patients waiting for isolated CABG. Guidelines to promote safer and fairer queuing for non-CABG cardiac surgery are needed. Shorter waiting lists, better compliance with existing guidelines, and guideline revisions to upgrade patients with left ventricular dysfunction could generate additional reductions in the already low risk of death for patients waiting for isolated CABG.

Figure 1

Distribution of waiting times for isolated coronary artery bypass graft surgery (CABG) (to completion) in Ontario, Canada for more than 22 000 patients between October 1991 and June 1995.

Figure 2

Distribution of waiting times and deaths while waiting for isolated coronary artery bypass graft surgery (CABG) by typical urgency categories used in Ontario⁹: surgery scheduled for one to two weeks after joining the waiting list is deemed to be "urgent" or "semi-urgent"; patients scheduled for operation at two to six weeks are considered to be on the "short list"; procedures scheduled for six weeks to three months are considered to be "elective"; and those of more than three months are low priority.