“As much as we would like one, there is no simple headline message. … There may be more than one reason why postoperative admission to an ICU does not appear to benefit patients in this study.”
MORE than 310 million patients undergo surgical treatments each year.1 Although many such procedures are uneventful, we know that a proportion of patients will develop serious complications that impact on their survival and quality of life, both in the days that follow surgery and in the long term.1,2 There are many components to a safe and effective perioperative care pathway, but postoperative admission to an intensive care unit (ICU) is commonly regarded as an important standard for many complex major procedures.3 Indeed, differences in availability and use of an ICU are often cited as a cause of variation in patient outcomes after surgery.3,4 Nevertheless, the evidence base for this expensive treatment remains far from clear. In this issue of Anesthesiology, Wunsch et al.5 report the findings of an important analysis of a large Medicare data set exploring the association between mortality, length of hospital stay, and healthcare costs with ICU admission for patients older than 65 yr undergoing one of five major surgical procedures between 2004 and 2008. Although they demonstrate a wide variation in rates of surgical ICU admission between hospitals, there was no associated reduction in mortality. Limitations of the data set precluded any discrimination between patients admitted directly to an ICU after surgery and those admitted on an emergency basis, having developed life-threatening complications. In other respects, the analysis is rigorous and objective. The findings, however, are perplexing to those of us who work in this field. Could it possibly be that ICU admission after major surgery does not confer benefit? It is worth noting the caution with which the authors interpret their findings. As much as we would like one, there is no simple headline message. As clinicians, we must carefully consider how these findings should affect our practice. There may be more than one reason why postoperative admission to an ICU does not appear to benefit patients in this study.
The first point to consider is that ICU is not a treatment we can test in a randomized trial; few patients would agree to take part. We must, therefore, use Health Services Research analyses of large data sets to perform what is often called a “natural trial,” comparing outcomes for similar patients allocated to different standards of care as part of their routine treatment. This approach can be very powerful, but the real challenge is to understand enough about each patient to allow robust statistical adjustment for baseline risk. Some patients may be admitted to an ICU as a routine part of the care package for a specific procedure, but others are admitted because the treating clinician has spotted something that suggests that they are more likely to die. If baseline data fail to describe this risk, then important differences between patients are not accounted for, and unmeasured confounding results. In the case of postoperative ICU, this form of bias is likely to result in the erroneous suggestion that the treatment either does not work, or may even be harmful. The second important consideration for interpreting our natural trial is the difference between the intervention and control treatments. The traditional role of an ICU is to provide organ support, such as invasive ventilation, inotropic therapy, and renal replacement therapy. Yet, few surgical patients require organ support after surgery, even among the high-risk group. What these patients do need is the prompt and effective treatment of pain, hypothermia, mild cardiorespiratory compromise, and fluid imbalance, with early mobilization and enteral nutrition where possible.3 Patients may be admitted to an ICU because staff there are used to addressing these needs, but this proactive care is also delivered in less intensive environments. We know that adequate staffing of surgical wards with qualified nurses improves patient safety and may reduce the incidence of postoperative complications.6 In hospitals that deliver excellent ward-based care, the incremental benefit of ICU admission will be reduced.
Wunsch et al. must be congratulated on tackling this complex problem and for providing a robust analysis with a balanced interpretation. We agree that this work should not drive any immediate change in patient care but instead a global research strategy to define the ideal care pathway for high-risk patients after major surgery and the role of an ICU within this. In particular, we need to study the value of specific treatments traditionally provided in an ICU, for example, minimally invasive cardiovascular and respiratory support,7 and to consider the best environment for their delivery. Postanesthesia care units and specialist high-dependency units may offer the desired benefits of an ICU at a much lower cost. We must also explore what it is about an ICU that we believe may help. Those who have experienced major surgery will agree that the importance of excellent proactive nursing care must not be underestimated, even it is not called intensive care.
The authors are not supported by, nor maintain any financial interest in, any commercial activity that may be associated with the topic of this article.