Measuring and achieving the best possible outcomes in surgery

Minimizing postoperative morbidity is key to establishing that benefit to the patient exceeds harm. Over the past 10 years, standardized descriptors for the measurement of postoperative complications have evolved from the Clavien–Dindo classification1,2 to the Comprehensive Complication Index (CCI®)3–5. This article reviews the contribution of the former and development of the latter to see what future steps should be taken to achieve the best possible outcomes in surgery around the globe. In an era when mortality has become less central as surgery and perioperative care has become safer, the focus of improving outcomes has shifted to reducing complications and regaining a good quality of life6,7. The Clavien–Dindo classification1,2, derived from work published in 19928, was an important first step in defining the severity of postoperative complications. It categorized complications into five grades (with subgrades) based on the need to treat complications. This therapy-based rather than symptom-based definition of the severity of complications greatly facilitated a standardized, reproducible measurement1,7, which is now widely adopted4,5. A limitation of the Clavien–Dindo classification became evident, however, in patients with more than one complication2,9. For simplicity, many authors reported only the most severe complication. This under-reporting of postoperative adverse events may have underestimated the true postoperative burden. Even if all complications in a patient were graded according to this classification, a tabular listing of all complications was required, making outcome comparison and interpretation difficult. This led to the development and introduction of the CCI®3,4, a method that integrates all recorded complications into a single formula, developed by adopting methods from operation-risk-index analysis used in economic sciences. Based on the Clavien–Dindo classification for grading individual complications, the CCI® metric integrates the postoperative course on a scale ranging from 0 (no complication) to 100 (death), more accurately representing the overall postoperative burden with a single number (for an online calculator see http://cci.assessurgery.com)3. The CCI® has additional advantages. It is more likely to identify clinically meaningful differences, for instance between open surgical or minimally invasive procedures, because it integrates more information4. This might reduce sample sizes for future studies, but may also minimize the risk of falsely concluding that two treatments yield the same outcome4. With the development of a valid tool to measure the impact of complications, it opens doors for research as well as being applicable in daily surgical practice, leading to quality improvements and better outcomes. The concept of defining ‘the best possible outcome in surgery’ has been proposed recently. The CCI® for 5202 healthy living liver donors from 12 high-volume centres worldwide was calculated10. The premise was that these healthy donors represented the minimum postoperative burden in patients undergoing major hepatectomy. This concept can easily be applied to different patient groups and procedures, and help define benchmarks that surgical centres may achieve. Ongoing multicentre studies are under way to define benchmark values for oesophageal and gastric surgery, liver transplantation and two-stage hepatectomies. It is now proposed that ‘best possible outcomes’ is the starting point for quality improvement cycles. This style of benchmarking facilitates comparisons of postoperative complications between centres, allowing the identification of what works well and seeing where there might be opportunities for improvement. Benchmarking is a well established concept for quality improvement in many industries and processes. It is defined as a continuous cycle of defining the best, comparing with the best and learning from the best. This concept should appeal to every surgeon who wishes to perform at the highest possible level. Research is still needed, however, to find approaches for defining best possible outcomes as benchmarks that are not simply arbitrary or too dependent on the hospitals used to define them. It is also important to find ways to incentivize surgical teams not merely to perform within acceptable limits, but also to push the limits of excellence in terms of improving patient outcomes11. Standardizing the measurement of postoperative complications is central to comprehensive learning about the harm associated with surgery, but this is only part of the journey towards