title: Towards closing the gap of the global surgeon, anaesthesiologist, and obstetrician workforce: thresholds and projections towards 2030.
abstract: BACKGROUND
  Billions of people are without access to surgical care, in part because of the inequitable distribution of the surgical workforce. Drawing on recently collected data for the number of surgeons, anaesthesiologists, and obstetricians worldwide, we sought to show their global maldistribution by identifying thresholds of surgical workforce densities, and by calculating the number of additional providers needed to reach those thresholds.
  
  
  METHODS
  From the WHO Global Surgical Workforce Database, national data for the number of specialist surgeons, anaesthesiologists, and obstetricians per 100 000 population (density) were compared with the number of maternal deaths per 100 000 live births (maternal mortality ratio; MMR) in WHO member countries. A regression line was fit between density of specialist surgeons, anaesthesiologists, and obstetricians and the logarithm of MMR, and we explored the correlation for an upper and a lower density threshold. Based on previous estimates of the global volume of surgical procedures, a global average productivity per specialist was derived. We then multiplied the average productivity with the derived upper and lower threshold densities, and compared these numbers to previously estimated global need of surgical procedures (4664 procedures per 100 000 population). Finally, the numbers of additional providers needed to reach the thresholds in countries with a density below the respective threshold were calculated.
  
  
  RESULTS
  Each 10-unit increase in density of surgeons, anaesthesiologists, and obstetricians, corresponded to a 13·1% decrease in MMR (95% CI 11·3-14·8). We saw particularly steep improvements in MMR from 0 to roughly 20 per 100 000 population. Above roughly 40 per 100 000 population, higher density was associated with relatively smaller improvements in MMR. These arbitrary thresholds of 20 and 40 specialists per 100 000 corresponded with a volume of surgery of 2917 and 5834 procedures per 100 000 population, respectively, and were symmetrically distributed around the estimated global need of 4664 surgical procedures per 100 000 population. Our density thresholds are slightly higher than the current average in lower-middle income countries (16 per 100 000) and upper-middle-income countries (38 per 100 000), respectively. To reach the threshold of at least 20 per 100 000 in each country today, another 440 231 (IQR 438 900-443 245) providers would be needed. To reach 40 per 100 000, 1 110 610 (IQR 1 095 376-1 183 525) providers would be needed.
  
  
  CONCLUSIONS
  Assuming uniform productivity, a global surgical workforce between 20 and 40 per 100 000 would suffice to provide the world's missing surgical procedures. We concede that causality cannot be implied, but our results suggest that countries with a workforce density above certain thresholds have better health outcomes. Although the thresholds cannot be interpreted as a minimum standard, they are useful to characterise the global surgical workforce and its deficits. Such thresholds could also be used as markers for health system capacity.
  
  
  BACKGROUND
  None.
authors: Department of Clinical Sciences in Lund, Paediatric Surgery and Global Paediatrics, Faculty of Medicine, Lund University, Lund, Sweden. Electronic address: hampus.holmer@med.lu.se.
authors: Hampus
authors: H
authors: Holmer
authors: Harvard Interfaculty Initiative in Health Policy and Harvard Medical School, Boston, MA, USA.
authors: Mark G
authors: MG
authors: Shrime
authors: Massachusetts General Hospital, Department of Surgery, Program in Global Surgery and Social Change, Harvard Medical School and Department of Plastic and Oral Surgery, Boston Children's Hospital, Boston, MA, USA.
authors: Johanna N
authors: JN
authors: Riesel
authors: Program in Global Surgery and Social Change, Harvard Medical School and Boston Children's Hospital, Boston, MA, USA.
authors: John G
authors: JG
authors: Meara
authors: Department of Clinical Sciences in Lund, Paediatric Surgery and Global Paediatrics, Faculty of Medicine, Lund University, Lund, Sweden.
authors: Lars
authors: L
authors: Hagander