Data in recent decades have linked a host of genetic, environmental, sociodemographic, and clinical factors to risk of kidney disease. The population burden of kidney disease is known to correlate with socially defined factors in most societies across the world. This phenomenon is better documented in high-income countries, where racial/ethnic minority groups and people of low socioeconomic status carry a high burden of disease. Extensive data have demonstrated that racial and ethnic minorities (e.g., African Americans in the United States, Aboriginal groups in Canada and Australia, Indo-Asians in the United Kingdom, and others) are affected disproportionately by advanced and progressive kidney disease.10–12 The associations of socioeconomic status and risk of progressive CKD and eventual kidney failure also have been well described, with persons of lower socioeconomic status bearing the greatest burden.13,14

Recent works have associated apolipoprotein L1 risk variants15,16 with increased kidney disease burden among persons with African ancestry. In Central America and Southeastern Mexico, Mesoamerican nephropathy (also referred to as CKD of unknown causes) has emerged as an important cause of kidney disease. While multiple exposures have been studied for their potential role in CKD of unknown causes, recurrent dehydration and heat stress are common denominators in most cases.17 Other perhaps more readily modifiable risk factors for kidney disease and CKD progression that disproportionately affect socially disadvantaged groups also have been identified, including disparate rates and poor control of clinical risk factors such as diabetes and hypertension, as well as lifestyle behaviors.

Diabetes is the leading cause of advanced kidney disease worldwide.18 In 2016, 1 in 11 adults worldwide had diabetes and more than 80% were living in low- and middle-income countries19 where resources for optimal care are limited. Hypertension is also estimated to affect 1 billion persons worldwide20 and is the second leading attributed cause of CKD.18 Hypertension control is important for slowing CKD progression and decreasing mortality risk among persons with or without CKD. Hypertension is present in more than 90% of persons with advanced kidney disease,18 yet racial/ethnic minorities and low-income persons with CKD who live in high-income countries have poorer blood pressure control than their more socially advantaged counterparts.21

Lifestyle behaviors, including dietary patterns, are strongly influenced by socioeconomic status. In recent years, several healthful dietary patterns have been associated with favorable CKD outcomes.22 Low-income persons often face barriers to healthful eating that may increase their risk of kidney disease.23–25 People of low socioeconomic status often experience food insecurity (i.e., limited access to affordable nutritious foods), which is a risk factor for CKD26 and progression to kidney failure.27 In low-income countries, food insecurity may lead to undernutrition and starvation, which has implications for the individual and, in the case of women of child-bearing age, could lead to their children having low birth weight and related sequelae, including CKD.28 Rates of undernourishment are as high as 35% or more in countries such as Haiti, Namibia, and Zambia.29 However, in high-income countries, food insecurity is associated with overnutrition, and persons with food insecurity have increased risk of overweight and obesity.30,31 Further, food insecurity has been associated with several diet-related conditions, including diabetes and hypertension.

AKI is an underdetected condition that is estimated to occur in 8% to 16% of hospital admissions32 and is now well established as a risk factor for CKD.33 Disparities in AKI risk are also common, following a pattern similar to that observed in persons with CKD.34 AKI related to nephrotoxins, alternative (traditional) medicines, infectious agents, and hospitalizations and related procedures are more pronounced in low-income and lower-middle-income countries and contribute to increased risk of mortality and CKD in those settings.35 Importantly, the majority of annual AKI cases worldwide (85% of more than 13 million cases) are experienced in low-income and lower-middle-income countries, leading to 1.4 million deaths.36

The distribution of RRT technologies varied widely. On the surface, all countries reported having long-term hemodialysis services, and more than 90% of countries reported having short-term hemodialysis services. However, access to and distribution of RRT across countries and regions was highly inequitable, often requiring prohibitive out-of-pocket expenditure, particularly in low-income regions. For instance, more than 90% of upper-middle-income and high-income countries reported having chronic peritoneal dialysis services, whereas these services were available in 64% and 35% of low-income and lower-middle-income countries, respectively. In comparison, acute peritoneal dialysis had the lowest availability across all countries. More than 90% of upper-middle-income and high-income countries reported having kidney transplant services, with more than 85% of these countries reporting both living and deceased donors as the organ source. As expected, low-income countries had the lowest availability of kidney transplant services, with only 12% reporting availability, and live donors as the only source.

Considerable international variation was also noted in the distribution of the kidney care workforce, particularly nephrologists. The lowest density (<5 nephrologists per million population) was very common in low-income countries, whereas the highest density (>15 nephrologists per million population) was reported mainly in high-income countries (Fig. 2).4,43,44 Most countries reported nephrologists as primarily responsible for both CKD and AKI care. Primary care physicians had more responsibility for CKD care than for AKI care, as 64% of countries reported that primary care physicians are primarily responsible for CKD care and 35% reported that they are responsible for AKI care. Intensive care specialists were primarily responsible for AKI in 75% of countries, likely because AKI is typically treated in hospitals. However, only 45% of low-income countries reported that intensive care specialists were primarily responsible for AKI, compared with 90% of high-income countries; this discrepancy may be due to a general shortage of intensive care specialists in low-income countries.

Fig. 2.

Nephrologist availability (density per million population) compared with physician, nursing, and pharmaceutical personnel availability by country income level. Pharmaceutical personnel include pharmacists, pharmaceutical assistants, and pharmaceutical technicians. Nursing and midwifery personnel include professional nurses, professional midwives, auxiliary nurses, auxiliary midwives, enrolled nurses, enrolled midwives, and related occupations such as dental nurses. A logarithmic scale was used for the x-axis [log(x+1)] because of the large range in provider density. Data from Bello et al.,4 Osman et al.,43 and the World Health Organization (for pharmaceutical personnel: http://apps.who.int/gho/data/view.main.PHARMS and http://apps.who.int/gho/data/node.main-amro.HWF?lang=en, for nursing and midwifery personnel: http://apps.who.int/gho/data/view.main.NURSES, for physicians: http://apps.who.int/gho/data/view.main.92000).44

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The appropriate number of nephrologists in a country depends on many factors, including need, priority, and resources, and as such there is no global standard with respect to nephrologist density. Regardless, the demonstrated low density in low-income countries calls for concern as nephrologists are essential to provide leadership in kidney disease care, and a lack of nephrologists may result in adverse consequences for policy and practice. However, it is quite encouraging that the number of nephrologists and nephropathologists is rising in low-income and lower-middle-income countries, in part thanks to fellowship programs supported by international nephrology organizations.45 It is important to note that the role of a nephrologist may differ depending on how the health care system is structured. The density statistic merely represents the number of nephrologists per million population and provides no indication of the adequacy to meet the needs of the population or quality of care, which depends on volume of patients with kidney disease and other workforce support (e.g., availability of multidisciplinary teams).

For other care providers essential for kidney care, international variations exist in distribution (availability and adequacy). Overall, provider shortages were highest for renal pathologists, vascular access coordinators, and dietitians (with 86%, 81%, and 78% of countries reporting a shortage, respectively), and the shortages were more common in low-income countries. Few countries (35%) reported a shortage in laboratory technicians. This information highlights significant inter- and intra-regional variability in the current capacity for kidney care across the world. Important gaps in awareness, services, workforce, and capacity for optimal care delivery were identified in many countries and regions.4 The findings have implications for policy development with regard to establishment of robust kidney care programs, particularly for low-income and lower-middle-income countries.46 The Global Kidney Health Atlas has therefore provided a baseline understanding of where countries and regions stand with respect to several domains of the health system, thus allowing the monitoring of progress through the implementation of various strategies aimed at achieving equitable and quality care for the many patients with kidney disease across the globe.

How could this information be used to mitigate existing barriers to kidney care? First, basic infrastructure for services must be strengthened at the primary care level for early detection and management of AKI and CKD across all countries.46 Second, although optimal kidney care obviously should emphasize prevention to reduce adverse consequences of kidney disease at the population level, countries (particularly low-income and lower-middle-income countries) should be supported at the same time to adopt more pragmatic approaches in providing RRT. For example, acute peritoneal dialysis could be an attractive modality for AKI, because this type of dialysis is as effective as hemodialysis, requires far less infrastructure, and can be performed with solutions and catheters adapted to local resources.47 Third, kidney transplantation should be encouraged through increased awareness among the public and political leaders across countries, because this is the clinically optimal modality of RRT and it is also cost-effective, provided that costs of the surgery and long-term medication and follow-up are made sustainable through public (and/or private) funding.48 Currently, most kidney transplants are conducted in high-income countries in part because of lack of resources and knowledge in low-income and lower-middle-income countries, as well as cultural practices and absence of legal frameworks governing organ donation.48