Key study points:
1. 4% of study participants died before hospital discharge
2. Country of surgery, urgency of surgery, grade of surgery, ASA score, surgical specialty, existence of metastatic disease, diagnosis of cirrhosis, and age were all independently associated with post-operative mortality rates.
3. Most patients who died (73%) were not admitted to critical care at any point post-operation.
4. Unplanned admissions to critical care were associated with higher mortality rates compared to planned admissions.
Primer: Nearly 235 million surgeries are performed each year in over 50 countries worldwide. While studies have suggested that only a small minority of patients suffer from post-operative complications, given the large volume of operations, even a low adverse event rate would amount to millions affected. Further, research has suggested that complication rates differ depending on many factors, including patient characteristics, hospital features, and surgery type, yet most studies have been largely limited – taking place in only a few hospitals or focusing only on certain operations or patient populations. The authors of this large scale, multinational study sought to conduct a prospective analysis to look at post-operative mortality and critical care utilization on a national scale.
An overall mortality rate of 4% was found, with patients staying in the hospital for a mean duration of 3 days. 3,599 patients (8%) were admitted to critical care during their hospital stay with a median duration of stay 1.2 days in the critical care facility. Of those that died, 73% were never admitted to critical care. Other factors associated with mortality include:
In sum: This study found an overall post-operative mortality rate of 4%, a value higher than that postulated by various studies. It also confirmed, on a large, multi-national scale, previous research findings regarding the importance of surgery and patient factors in affecting post-operative mortality outcomes. Further, the authors noted that while only 5% of patients underwent planned admission to the critical care unit, 73% of the post-operative deaths occurred in patients who were never admitted to the CCU, suggesting that critical care resource underutilization may be contributing to mortality rates.
This study is the largest prospective, international study to date investigating post-operative mortality rates. However, the authors note several limitations to this study. First, there was heterogeneity in the patient populations represented for each country – while in some countries, the sample was large enough to generalize to the national population, for others, a large proportion of the data was gathered at university hospitals, possibly introducing selection bias to the study. Thus outcome and standards of care data for these countries may not provide a true representation. Second, while efforts were made to enroll every patient admitted for surgery during the study period, it is not known what percentage of eligible patients were enrolled and whether those not enrolled differed in any significant way from the study population. Finally, certain variables (e.g. ASA score, grade of the surgery, etc.) required some subjectivity on the part of the clinicians categorizing the patient, which may explain some of the variability seen in the data.