This international prospective study has provided data for a population of more than 46 000 unselected patients undergoing inpatient surgery from 28 European countries. 4% of included patients died before hospital discharge, which was a higher mortality rate than expected.2,3,6,13–16
We identified substantial differences in crude and risk adjusted mortality rates between countries. When compared with the UK, the recorded mortality rates for Poland, Latvia, Romania, and Ireland were higher even after adjustment for all identified confounding variables. This pattern could relate to cultural, demographic, socioeconomic, and political differences between nations, which might affect population health and health-care outcomes.
A major strength of our study was the large number of consecutive unselected patients enrolled in a multicentre and multinational setting. A vigorous approach to follow-up for missing and incomplete data provided a high-quality dataset for analysis. The dataset allowed us to explore probable prognostic factors and to adjust crude mortality rates to describe differences in outcomes between countries. Our analysis identified several factors associated with increased mortality. These findings suggest that surgery-related and patient-related factors interact to increase mortality risk. Only two comorbid disease categories were identified as independent variables. This finding probably arose because the ASA score was designed to describe the severity of coexisting medical disease.
Evidence suggests that critical-care-based cardiorespiratory interventions can improve outcomes among high-risk surgical patients.17–21
However, in our study, only 5% of patients underwent a planned admission to critical care with a median stay of about 1 day. Unplanned admissions to critical care were associated with higher mortality rates than were planned admissions. Remarkably, most patients who died (73%) were not admitted to critical care at any stage after surgery. Of patients who died after admission to critical care, 43% did so after the initial episode was complete and the patient had been discharged to a standard ward. These findings suggest a systematic failure in the process of allocation of critical care resources. This notion is consistent with previous reports of a failure to rescue deteriorating surgical patients with a detrimental effect on patient outcomes22
and the high incidence of myocardial injury in the days after surgery.23
For some patients with a poor prognosis, postoperative admission to critical care might have been deemed inappropriate—eg, after palliative surgery for disseminated malignancy. However, our data suggest these cases are few in number (<5% of patients had malignancy, ). Meanwhile other investigators have challenged the suggestion that patients should be offered surgery when the standard of postoperative care is unlikely to be adequate for their needs.2
The low rate of admission to critical care prevents any detailed comparison of this resource between nations. Further research is needed to better understand whether early admission to critical care can improve survival after major surgery.
Despite the large sample size, our study might not be truly representative of current practice across Europe because only a small proportion of European hospitals took part. Although in some countries the patient sample was large enough to show national practice, the high proportion of patients enrolled in university hospitals in other countries suggests a degree of selection bias. In particular, our data might not show the true surgical case-mix and standards of care in countries with a small number of participating hospitals. Although we planned to enrol every eligible patient undergoing surgery during the study period, we cannot be sure of the exact proportion of eligible patients included. Nonetheless, assuming the volume of surgery during the cohort week is typical of the participating hospitals, these centres undertake more than 2·3 million inpatient surgical procedures each year, which is 1% of the estimated volume of surgery taking place worldwide.1
Whether truly representative or not, our findings clearly describe a large cross-section of health care in Europe.
Some of our findings might be indicative of limitations of commonly used risk-adjustment variables with unexpected patterns of survival across categories for both ASA score and grade of surgery. This finding could result from the poor ability of clinicians to discriminate between the less severe categories of these variables. Random partitioning of the countries into three equal groups and repetition of the modelling exercise showed much the same results with regards to the OR of the relevant effect factors, showing some stability of the risk adjustment in subsets of countries. This stability was further confirmed in more complex models that included interactions between variables for which none of the interactions with the country factor contributed significantly to prediction. We identified other interactions that did significantly contribute to prediction but we did not record a substantial change in country effects when estimated from the extended model including these interactions. We therefore decided to use the simpler of the hierarchical models for the final analysis because our aim had been to construct a parsimonious model that practising clinicians would easily understand.
As far as we are aware, this was the first large, prospective, international assessment of surgical outcomes (panel
). In some countries, data are available that describe survival after specific procedures such as vascular, joint replacement, or bowel cancer surgery.24–26
However, these audits are poorly representative of overall national surgical populations because high-risk patients are under-represented. The few previous estimates suggest an overall mortality for unselected inpatient surgery of between 1% and 2%,2,3,6,13–16
but these values are representative of only a few health-care systems. In a previous study13
of national registry data from the Netherlands, 30 day mortality was reported as 1·85%, which is much the same as the crude hospital mortality of 2% for this country in the EuSOS study. In the UK, a prospective investigation2
with a very similar methods to EuSOS identified a postoperative critical care admission rate of 6·7%, which is much the same as to the value of 6% for EuSOS in the UK.2
However, 30 day mortality was 1·6% compared with 3·6% for 60 day in-hospital mortality for UK patients in EuSOS. Reports from nations outside Europe describe 30 day mortality rates from 1·3% to 2·0%.6,14,15
Panel. Research in context
We searched Medline for original research from the past 10 years describing mortality rates in large unselected national and international populations of patients undergoing non-cardiac surgery. We used the search terms “surgery”, “mortality”, and “complications” and widened our search to include retrospective analyses of health-care registries and prospective epidemiological studies. Publications were screened by title and then by abstract for relevance to the objectives of our study. Additionally, coinvestigators in various European nations searched for publicly available registry analyses reporting mortality rates for unselected populations of surgical patients. We identified seven large national studies2,3,6,13–16
describing mortality rates for the population of interest, three of which involved prospective data collection. No studies were identified that provided international comparative data. The last search was done on June 15, 2012.
As far as we are aware, this was the first large prospective international epidemiological study of unselected non-cardiac surgical patients and as such it provides a new perspective on mortality after surgery. A few national reports describe mortality rates from 1·3% to 2·0%.2,3,6,13–16
In our study, the overall crude mortality rate of 4% was higher than anticipated. We identified important variations in risk-adjusted mortality rates between nations, and critical care resources did not seem to be allocated to patients at greatest risk of death. Our findings raise important public health concerns about the provision of care for patients undergoing surgery in Europe.
Previous investigators have described the differences in provision of health services across Europe, in particular numbers of critical care beds.10,11
The reported seven-times greater provision of critical care beds for Germany than for the UK is likely to affect rates of admission to critical care and postoperative outcomes.10,11,27
This finding is in keeping with our present data that show a greater rate of admission to critical care after surgery in Germany than in the UK. Other studies have shown that fewer than a third of high-risk non-cardiac surgical patients are admitted to critical care after surgery in the UK despite high mortality rates,2–4
which is consistent with the results of our study; across Europe 73% of surgical patients who died were never admitted to critical care. This situation contrasts with perioperative care for cardiac surgical patients who by definition have severe comorbid disease and undergo major body cavity surgery followed by routine admission to critical care with mortality rates of less than 2%.28
Several reasons could explain why outcomes for cardiac and non-cardiac surgical patients differ but the quality of perioperative care is likely to be among the most important. The heath-care community increasingly recognises the importance of the entire perioperative care pathway including preoperative assessment, optimisation of coexisting medical disease, integrated care pathways relevant to the surgical procedure, WHO surgical checklists, advanced haemodynamic monitoring during surgery, early admission to critical care, acute pain management and critical-care outreach services, and hospital discharge planning together with the primary care physician.20,21
Routine audit and reporting of data for clinical outcomes has also proved a highly effective instrument for improvement of the quality of perioperative care.29
Our findings suggest both the need and potential to implement measures to improve postoperative outcomes. In addition to further research in this discipline, the root causes of this problem could be better understood through increased use of high-quality registries designed to capture robust data describing quality of care and clinical outcomes for surgical patients. This step would require increased funding for this specific area of health services research. The high mortality rate after surgery might be modified by changes in the organisation of care.20