Progress and challenges in improving surgical outcomes.

Surgical morbidity and mortality are rightly considered public health concerns. It has been estimated that more than 200 hundredmillionmajor surgical procedures are performed annually worldwide1. Risks vary widely, related to the procedure involved, as well as patient and provider factors. Across these clinically diverse populations, at least a million patients die and an order of magnitude more experience serious complications after surgery every year. Fortunately, recent evidence from the USA suggests trends toward improvement. Despite largely flat mortality rates for most high-risk cancer and cardiovascular procedures during the 1990s2, risks associated with these procedures began to fall steadily after the turn of the millennium3. These trends cannot be explained by case mix. In fact, most reports indicate that patients undergoing major inpatient procedures have become older and, by most measures, less healthy over time. Technological innovation may help explain declining mortality for some procedures, such as endovascular repair of abdominal aortic aneurysms, but for many procedures, basic surgical techniques have changed little in the past two decades. So why is surgery becoming safer? In the simplest terms, there are two basic mechanisms for improving patient outcomes: direct patients to hospitals and surgeons with the best results, and improve care everywhere. With regard to the former, the past decade has seen significant concentration of complex cancer procedures in many Westernized healthcare systems. In the USA hundreds of low-volume hospitals stopped performing procedures such as pancreatectomy and oesophagectomy, and median hospital volumes rose sharply3. Redistribution of surgical patients to higher-volume, lowermortality hospitals was a significant factor underlying declining mortality for many cancer operations. It, nevertheless, explained less than half of the overall effect. Concentration of patients and expertise played no role in safer cardiovascular surgery. Mortality after cardiac and peripheral vascular procedures declined just asmuch as that after cancer surgery, despite trends toward fewer overall procedures dispersed across an increasing number of hospitals in the USA. Such evidence indicates that surgical mortality is falling at hospitals across the entire performance spectrum. Their respective contributions remain speculative, but several factors may be responsible.