Risk of cardiac events after elective versus urgent or emergent noncardiac surgery: Implications for quality measurement and improvement

INTRODUCTION

Patient populations differ for elective vs urgent and emergent surgery. The effect of this difference on surgical outcome is not well understood and may be important for improving surgical safety. Our primary hypothesis was that there is an association of surgical acuity with risk of postoperative cardiac events. Secondarily, we examined elective vs urgent and emergent patients separately to understand patient characteristics that are associated with postoperative cardiac events.

METHODS

We performed a retrospective cohort study of patients ≥65 years undergoing noncardiac elective or urgent/emergent surgery. Logistic regression estimated the association of surgical acuity with a postoperative cardiac event, which was defined as myocardial infarction or cardiac arrest within 30 days of surgery. For the secondary analysis, we modeled the outcome after stratifying by acuity.

RESULTS

The study included 161,177 patients with 1014 cardiac events. The unadjusted risk of a postoperative cardiac event was 3.2 per 1000 among elective patients and 28.7 per 1000 among urgent and emergent patients (adjusted odds ratio 4.10, 95% confidence interval 3.56-4.72). After adjustment, increased age, higher baseline cardiac risk, peripheral vascular disease, hypertension, worse American Society of Anesthesiologist (ASA) physical classification, and longer operative time were associated with a postoperative cardiac event. Higher baseline cardiac risk was more strongly associated with postoperative cardiac events in elective patients. In contrast, worse ASA physical classification was more strongly associated with postoperative cardiac events in urgent and emergent patients. Black patients had higher odds of a postoperative cardiac event only in urgent and emergent patients compared to White patients.

CONCLUSIONS

Quality measurement and improvement to address postoperative cardiac risk should consider patients based on surgical acuity.

Limitations to Health Care Quality Measurement: Assessing Hospital Variation in Risk of Cardiac Events After Noncardiac Surgery

Limited sample size, incomplete measures, and inadequate risk adjustment adversely influence accurate health care quality measurements, surgical quality measurements, and accurate comparisons among hospitals. Since these measures are linked to resources for quality improvement and reimbursement, improving the accuracy of measurement has substantial implications for patients, clinicians, hospital administrators, insurers, and purchasers. The team examined risk-adjusted differences of postoperative cardiac events among 20 geographically dispersed, community-based medical centers within an integrated health care system and compared it with the National Surgical Quality Improvement Program (NSQIP) hospital-specific differences. The exposure included the hospital at which patients received noncardiac surgical care, with stratification of patients by the acuity of surgery (elective vs. urgent/emergent). Among 157,075 surgery patients, the unadjusted risk of cardiac event per 1000 ranged among hospitals from 2.1 to 6.9 for elective surgery and from 10.3 to 44.5 for urgent/emergent surgery. Across the 20 hospitals, hospital rankings estimated in the present analysis differed significantly from ranking reported by NSQIP (P for difference: elective, P = 0.0001; urgent/emergent, P < 0.0001) with significantly and substantially lower variation after risk adjustment. Current surgical quality measures may not adequately account for limitations of sample size, data capture, adequate risk adjustment, and surgical acuity in a given hospital, particularly for rare outcomes. These differences have implications for quality reporting and may introduce bias into hospital comparisons, particularly for hospitals with incomplete capture of their patients' baseline risk and acuity.