region reported a lack of nephrology training programs, and only 41% of low-income countries had such training. This gap is a major limiting factor for the abilities of countries to produce the future nephrologist workforce and to achieve self-reliance in providing kidney care to their populations. To scale up their nephrologist workforce, countries need to focus on producing local qualified professionals, ideally through partnerships with other countries and organizations with sufficient resources to help them establish training programs. For instance, as part of its building capacity and outreach initiative, the ISN has a fellowship program for trainees to travel to an advanced center to obtain skills and training and then return to their home country to practice.33 Since its inception, the program has sponsored more than 600 fellows.34 Another gap highlighted in this study was a shortage of all nephrology care providers across all ISN regions and World Bank income groups. The most frequently reported shortages were in renal pathologists and vascular access coordinators. Such shortages of health care providers exacerbate the adverse impacts of nephrologist shortages on kidney care that exist in many parts of the world. Health care policies in such countries should ideally cater to and support commensurate scaling up of all nephrology care providers (such as NPs, dialysis nurses, and physician assistants) rather than focusing narrowly on nephrologists and/or physicians. Strengths and limitations of the study. This is the most comprehensive study of the global nephrology workforce and training capacity to date. The study had a high response rate and adequate representation of the world population (>93%). An established method was used to define and monitor current global nephrologist and nephrology trainee capacities. Specifically, health workforce density was used to estimate health workforce relative to the population size, as recommended by the WHO in its building blocks of health systems handbook.21 This indicator had the advantages of being simple to calculate and analyze, and being easy to understand and present to a broad audience. However, it did not take into account all dimensions critical for health workforce, such as quality, efficiency, accessibility and geographic distribution of health workforce, and annual output of health care graduates.21 This may have led to underestimation of the actual capacity of the nephrology workforce and warrants the need for further research. In the present survey, countries provided information on availability, duration, and structure of training. Other important factors in addressing training capacity are quality of training, volume, and location within the country, all of which were review MA Osman et al.: Health workforce for nephrology care: existing manpower and training capacity 60 Kidney International Supplements (2018) 8, 52–63 beyond the scope of this paper. Physicians who specialize in the management of kidney disorders (nephrologists) are the primary providers of kidney care in many parts of the world. However, depending on the region and health care setting, other caregivers such as PCPs may assume the role of nephrologists in providing kidney care. As there is no agreed standard for nephrologist density, the current study used calculated global densities of nephrologists and nephrology trainees to describe each country’s and region’s current nephrology workforce relative to the rest of the world. Priorities and recommendations for action. 1. Scale up the current nephrology workforce through training qualified providers by implementing evidencebased, competence-based, and community-oriented curriculums.35,36 2. Develop robust methodology to collect data and monitor the current and future nephrology workforce.21 3. Increase use of allied health professionals to increase efficiency and decrease the load on nephrologists through task substitution and/or sharing while maintaining high standards and optimal patient-important outcomes.31,32,37–40 4. Leverage cost-effective technology to increase access to specialist care while building the scope of PCPs and other allied health professionals in managing and improving outcomes of kidney patients.41–44 5. Augment research and scholarly activity in nephrology workforce development, management, and maintenance.45 Future work. The results of this study show a significant gap in the nephrology workforce. There is a need to move beyond the numbers and conduct more research to ascertain the other factors that influence workforce development and monitoring, such as distribution within countries and regions, demographics and age of the current workforce, and annual graduation rate of nephrologists, PCPs, NPs, and other nephrology health care providers. Moreover, there is a pressing need to research how to maximize the roles of PCPs and allied health professionals in sharing the management of kidney disease with nephrologists. In conclusion, this study involved examining global nephrology workforce and training capacity, an essential component of any country’s health care system and especially important in nephrology to face the growing burden of kidney disease globally. With the finding of shortages of nephrologists and all health workforce related to nephrology, it can be concluded that in most