July 14, 2017



Postoperative complications occur in up to 20% of patients and short-term mortality varies from 1 to 4%. The value of routine admission of high-risk patients to critical care after surgery is unclear, with widespread inequity in the allocation of this resource.


Kahan et al conducted an analysis were to assess the association between provision and use of critical care resources and in-hospital mortality after elective surgery [1]. 


All adult patients undergoing elective surgery with a planned overnight stay in hospital. 


The mortality of patients admitted directly to critical care after surgery were compared to patients admitted to a standard ward.


Prospective observational cohort study. During the International Surgical Outcomes Study (ISOS) patient- and hospital-level data describing critical care utilisation following elective surgery in 27 countries was collected [2]. Participating countries selected a single data collection week between April and August 2014. 

The following analyses were conducted: 

1. Patient-level analysis of association between critical care admission and mortality. The association between admission directly to critical care after surgery (versus admission to a standard ward) and in-hospital mortality. A mixed-effects logistic regression model with a random intercept for country was conducted.

2. Hospital-level analysis of mortality and critical care admission immediately after surgery. The association between the hospital rates of critical care admission and hospital rate of risk-adjusted postoperative mortality 

3. Hospital-level analysis of mortality and critical care admission to treat a postoperative complication. The association between critical care admission to treat a life-threatening postoperative complication and the risk-adjusted mortality rate at the hospital level 

4. Hospital-level analysis of association between mortality and critical care capacity. The association between critical care capacity, defined as the number of critical care beds as a pro- portion of the total number of hospital beds 

Two post-hoc sensitivity analyses were conducted. The first included only high risk patients (ASA III or IV who underwent major surgery) and the second used an interaction test for university vs. non-university hospitals.


• 44,814 patients from 474 hospitals were included in the main database. Patients admitted to critical care after surgery were older, had higher ASA scores, and were more likely to have co-morbid disease. Patients in low or middle income countries were younger, had lower ASA scores, and were less likely to have co-morbid disease. 

• Patients admitted to critical care directly after surgery had a higher mortality rate (2.4%) than patients admitted to a standard ward (0.3%). After risk adjustment, the odds ratio for mortality was 3.01 (2.10–5.21; p < 0.001). 

• There was no association between critical care admission immediately after surgery, critical care admission to treat a postoperative complication, or critical care capacity and mortality.

• Post hoc sensitivity analyses revealed no significant effect of any critical care measure in the high-risk subgroup of patients. University hospital status had no influence on the relationship between post-operative mortality and critical care admission to treat a postoperative complication or critical care capacity.

Discussion and limitations

• It is not possible to rule out any residual confounding due to unknown variables or interactions in the risk adjustment models. This is likely to explanation for the apparent excess mortality associated with critical care admission in the patient-level analysis. 

• Many hospitals deliver excellent ward-based care, including provision of intermediate care wards. Therefore, any additional benefit of critical care admission may not be evident. 

• Furthermore, this analysis cannot correct for any variation in critical care resource allocation to the surgical patients at greatest risk of death because of inadequate risk assessment, or failure of the methods used for doing so. 

• The findings may also be limited by the low event rate for mortality, and cannot be extrapolated to postoperative care for patients undergoing emergency procedures. 


There was no identifiable survival benefit from postoperative admission to critical care, either at the patient level or the hospital level. The authors “urge caution in the interpretation of these findings” and conclude that “isolated measures to increase postoperative admission to critical care may not alone be sufficient to reduce mortality”. 

Article review prepared and submitted by EJRC member Nish Arulkumaran, MD (Centre for Intensive Care Medicine, University College London, London, UK).


1. Kahan BC, Koulenti D, Arvaniti K, et al. Critical care admission following elective surgery was not associated with survival benefit: prospective analysis of data from 27 countries. Intensive care medicine. Jul 2017;43(7):971-979.

2. International Surgical Outcomes Study group. Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries. British journal of anaesthesia. Oct 31 2016;117(5):601-609.

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