title: How much surgery is enough? Aligning surgical delivery with best-performing health systems.
abstract: BACKGROUND
  Surgical delivery varies 150-fold across countries. However, no direct correlation exists between surgical delivery and health outcomes, making it difficult to pinpoint a goal for surgical scale-up. We attempted to determine the amount of surgery that would be delivered worldwide, if the world aligned itself with countries providing the best health outcomes.
  
  
  METHODS
  The number of cases performed annually has previously been published for 55 countries, which we stratified by World Bank income group. Life expectancy, maternal mortality, under-5 mortality, adult mortality, and a composite outcome of the four were plotted against reported surgical delivery. Univariate and multivariate polynomial regression curves were fit, and the optimum point on each regression curve was determined by solving for first-order conditions. The country closest to the optimum for each health outcome was taken as representative of the best-performing health system. Monetary inputs to, and surgical procedures provided by, these health systems were scaled to the global population.
  
  
  RESULTS
  For the five health outcomes, four countries (Sweden, Germany, Singapore, and Canada) performed at the optimum. Currently, 318 million procedures are provided annually around the world. If global surgical delivery mirrored delivery in the four best-performing countries, however, between 630 million (maternal survival) and 870 million cases (composite outcome) would be provided annually. With population growth, this will increase to between 750 million and 1 billion annual cases, respectively, by 2030. The best-performing health systems spend roughly 10% of their gross domestic product on health-care, providing 9000-12 000 cases per 100 000 individuals in the population.
  
  
  CONCLUSIONS
  To the best of our knowledge this is the first study to provide empirical evidence for the surgical output that an ideal health system would provide. The findings in this study provide a potential goal for surgical scale-up around the world.
  
  
  BACKGROUND
  National Institutes of Health/National Cancer Institute.
authors: Department of Global Health and Population, Harvard School of Public Health, Boston, MA, USA; Department of Otology and Laryngology, Harvard Medical School, Boston, MA, USA; Office of Global Surgery, Massachusetts Eye and Ear Infirmary, Boston, MA, USA; Program in Global Surgery and Social Change, Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, USA. Electronic address: shrime@mail.harvard.edu.
authors: Mark G
authors: MG
authors: Shrime
authors: Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA, USA.
authors: Kimberly M
authors: KM
authors: Daniels
authors: Program in Global Surgery and Social Change, Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA, USA; Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA, USA.
authors: John G
authors: JG
authors: Meara