Case definitions and approaches for surveillance of chronic kidney disease in agricultural communities in Central America: policy implications
Authors: Pedro Ordunez, Wendy E. Hoy
Journal: Kidney International (2018)

From estimates of the Institute of Health Metrics and Evaluation,1Institute of Health Metrics and Evaluation. Global Burden of Disease 2015(Internet). 2017. Available at: http://ihmeuw.org/416u. Accessed August 24, 2017.Google Scholar chronic kidney disease (CKD) was among the top 10 contributors to age-standardized disability-adjusted life years in Central Latin America in 2015, and in the preceding 15 years its ranking rose from 18th to fifth place. CKD-attributable disability-adjusted life years are higher among men than women, although rates in women are increasing more rapidly. Over the past 20 years, many community reports2Almaguer M. Herrera R. Orantes C.M. Chronic kidney disease of unknown etiology in agricultural communities.MEDICC Rev. 2014; 16: 9-15Crossref PubMed Google Scholar have described an excess of cases of CKD in this region, specifically a form of chronic interstitial nephritis (termed CKD of nontraditional causes or CKDnT). This condition has been ravaging a cluster of farming communities across Central America. There has also been a dramatic impact of CKD on mortality (coded as CKD N-18, ICD-10), mainly in Nicaragua and El Salvador, related to thousands of deaths in the last decade, many of them in persons under 60 years of age.3Ordunez P. Saenz C. Martinez R. et al.The epidemic of chronic kidney disease in Central America.Lancet Glob Health. 2014; 2: e440-e441Abstract Full Text Full Text PDF PubMed Scopus (41) Google Scholar Accordingly, in the fall of 2013, ministers of health of the Americas asked Pan American Health Organisation (PAHO) to develop a framework for surveillance of CKDnT for the region. Limited access to health services, insufficient health data, and lack of standard case definitions, among other factors, have limited our capacity to understand and track this epidemic. The aims of this piece are to introduce and discuss the contents and the policy implications of the recent PAHO technical publication titled "Epidemic of Chronic Kidney Disease in Agricultural Communities in Central America. Case definitions, methodological basis and approaches for public health surveillance."4Pan American Health OrganizationEpidemic of Chronic Kidney Disease in Agricultural Communities in Central America. Case Definitions, Methodological Basis and Approaches for Public Health Surveillance.in: Hoy W. Ordunez P. Pan American Health Organization, Washington, DC2017: 37Google Scholar This document was developed in consultation with a wide range of experts, through an extended iterative process, using the most current available data. The PAHO document presents a background to this epidemic, including its epidemiology and updated mortality estimates. It describes progress toward case definitions for surveillance of CKDnT, as formulated by the appointed experts, along with some views of the editors about these definitions. It includes outlines of staging and diagnosis of CKD, according to the Kidney Disease Improving Global Outcomes international standards, a description of clinical and pathological characteristics of CKDnT, and the first attempted CKDnT case definitions, developed for the purposes of CKDnT surveillance. These case definitions, which have been recently published,5Lozier M. Turcios-Ruiz R.M. Noonan G. Ordunez P. Chronic kidney disease of nontraditional etiology in Central America: a provisional epidemiologic case definition for surveillance and epidemiologic studies.Rev Panam Salud Pública. 2016; 40: 294-300PubMed Google Scholar, 6Ferreiro A. Álvarez-Estévez G. Cerdas-Calderón M. et al.Confirmed clinical case of chronic kidney disease of nontraditional causes in agricultural communities in Central America: a case definition for surveillance.Rev Panam Salud Pública. 2016; 40: 301-308PubMed Google Scholar, 7Escamilla-Cejudo J.A. Lara Báez J. Peña R. et al.Optimización del registro de muerte por enfermedad renal crónica en las comunidades agrícolas de América Central.Rev Panam Salud Publica. 2016; 40: 285-293PubMed Google Scholar flowed from an extensive consensus process conducted earlier with the US Center for Disease Prevention and Control, the Latin American Society of Nephrology, PAHO technical experts, and several experts from the most affected countries of Central America. These case definitions included suspected and probable cases of CKDnT,5Lozier M. Turcios-Ruiz R.M. Noonan G. Ordunez P. Chronic kidney disease of nontraditional etiology in Central America: a provisional epidemiologic case definition for surveillance and epidemiologic studies.Rev Panam Salud Pública. 2016; 40: 294-300PubMed Google Scholar and confirmed clinical cases of CKDnT.6Ferreiro A. Álvarez-Estévez G. Cerdas-Calderón M. et al.Confirmed clinical case of chronic kidney disease of nontraditional causes in agricultural communities in Central America: a case definition for surveillance.Rev Panam Salud Pública. 2016; 40: 301-308PubMed Google Scholar Furthermore, an algorithm was developed for notification and reporting of mortality of CKDnT.7Escamilla-Cejudo J.A. Lara Báez J. Peña R. et al.Optimización del registro de muerte por enfermedad renal crónica en las comunidades agrícolas de América Central.Rev Panam Salud Publica. 2016; 40: 285-293PubMed Google Scholar The PAHO document summarizes the methodology and conceptual basis for surveillance of CKD and CKDnT, advocating for a comprehensive and nonvertical approach. It also describes complementary approaches for surveillance, the menu of options (e.g., active and passive surveillance and population-based surveys) and it includes a framework for a data platform. Such a platform supports the use of dynamic and large data sets from heterogeneous sources flowing from several types of surveillance, to conduct comprehensive data analysis, produce effective data and information products (outputs), and improve communication and dissemination. Recently, conversations on CKDnT in Central America have seemed polarized around 2 main causal hypotheses. One is the heat stress–dehydration hypothesis, which is related to climate and harsh working conditions, whereas the other centers around environmental toxins, including those potentially related to the use of agrochemicals.8Jayasumana C. Orantes C. Herrera R. et al.Chronic interstitial nephritis in agricultural communities: a worldwide epidemic with social, occupational and environmental determinants.Nephrol Dial Transplant. 2016; 32: 234-241Google Scholar Instead, the authors of this current document propose a multideterminant model of causation, which proposes that organ damage can result from multiple risk factors, acute and chronic, which can act simultaneously or sequentially over the life course to amplify the injury caused by each. In such models, various categories of risk factors for CKD need not be mutually exclusive. Multideterminant models can pull together biological, environmental, occupational, and socioecological factors to contextualize the lives of those most affected. They allow contemplation of all feasible risk factors, and thus reconcile different theories of causation. Such models predict that mitigation of any factor with a significant contribution to risk might reduce ongoing end-organ damage (Figure 1). The multideterminant nature of kidney disease has been demonstrated in the high risk setting of remote living Australian Aborigines.9Hoy W.E. White A.V. Tipiloura B. et al.The influence of birthweight, past poststreptococcal glomerulonephritis and current body mass index on levels of albuminuria in young adults: the multideterminant model of renal disease in a remote Australian Aboriginal population with high rates of renal disease and renal failure.Nephrol Dial Transp. 2016; 31: 971-977PubMed Google Scholar This concept supports development of a comprehensive surveillance system that acknowledges the potential for a broad set of initiating and propagating risk factors. Cognizant of the various contexts where CKD and CKDnT epidemics are unfolding, this publication presents a menu of options for local, subnational, national, or even supranational surveillance systems. We propose a surveillance methodology menu and data platform framework (Figure 2) and a specific metric for monitoring and evaluation, through combinations of options. Such options include passive surveillance, based on routinely collected mortality and morbidity registry data, active surveillance, including sentinel surveillance, and repeated population-based surveys. Each country, based on its own resources and needs, can decide when, where, and which of these components should be prioritized. We envision that CKDnT surveillance should be embedded within a surveillance system for CKD generally, and for important noncommunicable diseases more broadly. Surveillance is an essential public health function and a nontransferable responsibility of health authorities. Health surveillance comprises the ongoing systematic collection, analysis, and interpretation of data, closely integrated with the timely dissemination of these data to those responsible for preventing and controlling disease. A surveillance system cannot be implemented successfully in the absence of an accessible health system that is ready to act in a timely and coordinated manner; otherwise, it would just be a data collection process operating in a vacuum, without integration into a coordinated public health response. In the context of the epidemic of CKDnT in Central America, the use of standard definitions of CKD and CKDnT will allow regions and countries to measure CKD and CKDnT-related incidence and prevalence and compare these data with those of other regions and countries worldwide. However, case definitions will change over time as surveillance improves and more evidence is gathered. For example, ineligibility of people age ≥ 60 years will probably be abandoned: with increasing life expectancy in these regions, CKDnT will be increasingly recognized in older people. Furthermore, older people with CKDnT are expressing factors that mitigate disease severity, which are important to define. In addition, in view of burgeoning rates of the metabolic/diabesity syndrome, automatic exclusion of people with diabetes and microangiopathy, as well as those with hypertension and end-organ damage should be relaxed, and the possibility of mixed renal pathologies acknowledged. However, the current definitions can underpin the initial implementation of surveillance mechanisms. Finally, we posit that multilevel interventions aligned with the social determinants of health and workers' health are needed to address this epidemic. The "health in all policies" approach should be adopted by governments, and intersectoral work among health care, industry, and labor sectors needs to be prioritized for a cohesive response to this epidemic. Employers and industry could be willing to participate in efforts to improve working conditions. Proper agrochemical regulations and environmental controls may substantially reduce disease appearance or progression. Hence, in accordance with the precautionary principle, they must be implemented, regardless of hypothesis or understanding of causation or mechanisms. Systemic surveillance needs to be implemented with the speed and urgency that match the gravity of this epidemic and the human suffering it is causing. All the authors declared no competing interests. The contents of this report are the responsibility of the authors and do not necessarily represent the official position of any of their affiliated institutions. WEH's program is supported by the University of Queensland and the CKD Centre for Research Excellence funded by the National Health and Medical Research Council of Australia (the NHMRC CKD.CRE) (grant number 1079502).