shortages in counselors and/or psychologists (40%), dialysis technicians (30%), transplant coordinators (20%), pharmacists (20%), and laboratory technicians (20%). More countries reported shortages of PCPs (30%) than of nephrologists (20%) or NPs (20%) (Supplementary Figure S2B). Discussion Summary of results and implications. The survey results showed marked inequities in the existing nephrology workforce and training capacities between countries, within regions, and across ISN regions and 2014 World Bank income groups. There were significant differences in nephrologist and nephrology trainee densities between high- and low-income countries, an absence of nephrology training programs in a large percentage of low-income countries, and shortages of all nephrology care providers in all income groups. Most countries with nephrology training programs reported training durations between 2 to 4 years, with few countries reporting more than 4 or less than 2 training years. The majority of countries reported their nephrology training structure as subspecialty training following general internal medicine, while the rest reported either solo training after primary medical qualification or a mixed system depending on the region and/or training center. Gaps, threats, and opportunities toward sustainable provision of nephrology workforce. This study has identified several important gaps in the existing global nephrology workforce MA Osman et al.: Health workforce for nephrology care: existing manpower and training capacity review Kidney International Supplements (2018) 8, 52–63 59 and training capacity. A key gap in kidney care was the significant variation in nephrologist density across income groups and ISN regions. This gap was most prominent in low-income countries, which reported a nephrologist density of just 0.31 PMP but accounted for more than one-half of the world’s population. Africa, with more than 1.2 billion in population, and South Asia, home of one-fourth of the world’s population, had the lowest densities of nephrologists (3.64 PMP and 1.17 PMP, respectively). These highly populated regions face the same increases in demand for health services for noncommunicable diseases as the rest of the world, in addition to the burden of communicable disease.10 The shortage can be attributed to many factors, such as limited physician training capacity23 and immigration of skilled workers across and between regions.24 Some opportunities to address this challenge include increasing workforce retention by providing incentive and opportunities for professional development locally in low-income countries and adopting policies of fair recruitment in high-income countries.25 Another opportunity lies in building the scope of PCPs in kidney care management.26 There was also a gap in nephrology trainee density. Lowincome countries reported a trainee density 30 times lower than that of high-income countries. When analyzed by ISN region, 7 of the 10 lowest densities were in sub-Saharan Africa, and all countries from South Asia reported trainee densities below the global average. In contrast, all countries from North America and Western Europe reported densities above the global average. Considerable disparity was also found within ISN regions; for example, in the North and East Asia ISN region, China reported a trainee density 30 times lower than that of Japan. Although this study’s results showed adequate current nephrology trainee densities in high-income countries, many studies have shown decreased interest in the field.14,27 Some high-income countries rely on foreign-trained doctors to cover shortages in nephrology manpower. For example, a study from Oman showed that the majority of practicing nephrologists were expatriate physicians, with local doctors representing only 14% of the workforce.28 In the United States, a recent report showed that international medical graduates represented 47% of active nephrologists and 65% of nephrology trainees.29 A recent survey from Canada suggested that, although the current nephrologist workforce may have been adequate until now, the number of trainees may not adequately meet future demand.30 Scaling up the current nephrologist workforce may not be feasible, especially for low-income countries, because it requires investment of time and money to produce highly qualified nephrologists. However, countries who are short in supply of nephrologists and face large demands for kidney care may adopt alternative models of care in the short term. One suggested approach is involving nursing and allied health care professionals through task substitution and sharing to increase efficiency of care and decrease nephrologist workload while maintaining high standards and optimal patient important outcomes.31,32 Countries may need 9 to 10 years to produce 1 physician, and many countries with critical shortages of nephrologists cannot afford the time lag, nor possibly the cost of training. An at least partial solution may be found in utilizing allied health care professionals, but it is important that they be held to high standards of accreditation and training in nephrology care to maintain the quality of patient care. Nephrology training programs were absent in many parts of the world. Almost one-half of the Africa ISN