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Effects on household income and earnings from chronic kidney disease of non-traditional origins: PREP project findings from Chichigalpa, Nicaragua
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  1. Heath Prince1,
  2. Thomas Boswell1,
  3. Jason Glaser2,3,
  4. Catharina Wesseling4,
  5. Ashweeta Patnaik1,
  6. William Martinez-Cuadra2
  1. 1 LBJ School of Public Affairs, The University of Texas at Austin, Austin, Texas, USA
  2. 2 La Isla Network, Washington, DC, USA
  3. 3 London School of Hygiene and Tropical Medicine, London, UK
  4. 4 Institute of Environmental Medicine, Unit of Occupational Medicine, Karolinska Institute, Stockholm, Sweden
  1. Correspondence to Dr Heath Prince, LBJ School, The University of Texas at Austin, Austin, Texas, USA; heath.prince{at}austin.utexas.edu

Abstract

Objective Our purpose with this study is to examine the socioeconomic outcomes associated with chronic kidney disease not related to well-known risk factors (CKDnt) in four communities in Chichigalpa, Nicaragua that are home to a substantial number of sugarcane workers.

Methods We employed a cluster-based systematic sampling design to identify differences in outcomes between those households affected directly by CKDnt and those that are not.

Results Overall, we find that approximately one-third of households surveyed had a household member diagnosed with CKDnt. 86% of CKDnt households reported that the head of the household had been without work for the last 6 months or more, compared with 53% of non-CKDnt households. Non-CKDnt households took in more than double the earnings income on average than CKDnt households ($C52 835 and $C3120, respectively). Nonetheless, on average, CKDnt households’ total income exceeded that of non-CKDnt households due to Nicaragua’s national Instituto Nicaraguense de Seguridad Social Social Security payments to CKDnt households, suggestive of a substantial economic burden on the state resulting from the disease. Households headed by widows or widowers who are widowed as a result of CKDnt demonstrate distinct deficits in total income when compared with either non-widowed households or to households widowed by causes other than CKDnt.

Conclusions Despite strong similarities in terms of demographic characteristics and despite residing in the same communities with similar access to the available resources, households experiencing CKDnt exhibit distinct and statistically significant differences in important socioeconomic outcomes when compared to non-CKDnt households.

  • Occupational Health
  • Agriculture
  • Developing countries
  • Kidney Diseases

Data availability statement

Data are available on reasonable request.

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WHAT IS ALREADY KNOWN ON THIS TOPIC

  • There is a growing body of evidence that strenuous work in high environmental temperatures without sufficient rest or hydration is an important driver of chronic kidney disease, and its prevalence is increasing among agricultural workers.

WHAT THIS STUDY ADDS

  • Our study begins to fill gaps in the occupational health literature by examining the links between health shocks, such as chronic kidney disease, and their effects on household and community economic health.

HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY

  • By examining the relationship between chronic kidney disease and household and community economic health, we provide researchers, practitioners and policy-makers with a more complete perspective on the impacts of the disease, extending beyond health effects.

Introduction

For over three decades, an epidemic of chronic kidney disease (CKD), not related to well-known risk factors such as diabetes and hypertension, and so known as CKD of non-traditional origins (CKDnt) or Mesoamerican nephropathy, has been detected among agricultural and other heavy labourers in Mesoamerica, particularly among sugarcane workers. There is a growing body of evidence that strenuous work in high environmental temperatures without sufficient rest or hydration is an important driver of the disease.1–3

In 2020, the National Science Foundation funded, as part of the Belmont Forum partnership, the Prevention, Resilience, Efficiency and Protection (PREP) programme.4 PREP has three primary foci:

  • Measuring the immediate and long-term impact that a hydration, shaded rest and ergonomic improvement intervention has on sugarcane workers’ health (kidney health and heat-related symptoms) and productivity.

  • Measuring the socioeconomic and resilience impacts of CKDnt on individuals, families, communities and health systems.

  • Conducting an analysis of public health policies to understand the role that they have played in the growth and mitigation of the disease.

This report presents baseline results from a household survey employed to address the second of these foci, comparing the difference in socioeconomic conditions between households in four communities in Chichigalpa, Nicaragua affected by CKDnt (ie, households in which a member currently has CKDnt or in which a member has passed away in recent years due to CKDnt) with those that are not affected by the disease.

Our primary research question with this component of the study is: do differences in the CKDnt-related health status of households account for observable differences in earnings, income, savings, education and other socioeconomic outcomes? The following presents our analysis of the baseline survey round, completed in December of 2021.

PREP contributes to the limited body of research on the economic impact of chronic disease at the household level. The growing prevalence of non-traditional kidney disease among agricultural populations has gained international attention from various actors focused on preventing occupational illness.5 The disease presents a challenge for employers, governments and those communities that must bear its social and financial burdens.6 7

Multiple epidemiological studies, using both quantitative and qualitative methods, have detected reduced kidney function in populations working under extreme heat conditions. For example, a study employing geographic information system (GIS) mapping techniques to track temperature burden in Central America identified a correlation between high average yearly temperatures and CKDnt.2 Studies have also identified pockets of the disease in Southeast Asia and India.3 Most CKDnt sufferers are young men, with a relatively high percentage of them developing the disease in their 20s and 30s.1 When these young men are also the primary wage earners for a family, the economic consequences can be assumed to be profound. In their framework, Suhrcke et al delineated among three main types of economic consequences stemming from chronic disease: those related to consumption and savings, labour supply and productivity effects, and education and human capital accumulation. They further define the consumption and savings consequences to include effects on a household’s ‘ability to hold consumption levels constant in the face of ‘health shocks’ from disease’,8 , p. 19 as well as costs associated with treating the disease. Suhrcke et al also note that there remains a need for additional studies that are based on survey data ‘that combine both relevant chronic disease proxies and the usual socioeconomic and demographic data’.8 , p. 25

In his study of health shocks in Vietnamese households, Wagstaff found that health shocks may be associated with increases in unearned income that partially offset reductions in earned income, as well as with large increases in medical spending and reductions in spending on food.9

Methods

We employed a disproportionate stratified systematic sampling tool to retrieve comparable data from CKDnt and non-CKDnt households in four neighbourhoods in Chichigalpa. The tool functions as an Excel worksheet that assigns a random interval for each cluster in the sample frame. The four subsamples correspond to the four neighbourhoods, and random intervals are identified once parameters are set and the total number of eligible households is recorded. The tool uses the random interval to list the numbers selected from each neighbourhood. The numbers listed after selection correspond to the household codes established during a community mapping exercise. This component of the study is carried out in collaboration with the La Isla Network, an international NGO studying CKDnt.

Our sample frame included 1961 home structures, of which 1851 were eligible to participate in the household survey after unoccupied structures were removed from the household list. We randomly selected 607 households from the eligible sample list. To ensure substantial representation in the data for CKDnt households, we drew 80% of our sample from the two communities that were known locally to have a relatively higher number of households with members working in the agricultural sector. We drew 20% of our sample from the two communities known to contain workers working across a relatively equal distribution of sectors. Differences in outcomes between CKDnt and non-CKDnt households were identified primarily through hypothesis-testing (t-tests). Null hypotheses were rejected when results indicated a p value of 5% or below.

We employed a questionnaire that combined questions adapted from UNICEF’s Multiple Indicator Cluster Survey,10 as well as from USAID’s Resilience, Evaluation, Analysis and Learning questionnaire.11 The study began in May 2021 with the GIS mapping of a household sample frame. Data collection began in June 2021, was paused for the Nicaraguan presidential election, resumed in November 2021 and concluded in December 2021. In total, 606 questionnaires were analysed.

Table 1 presents those variables that we believe best reflect the topic on which our study is focused, namely income, earnings and widowhood status differences between two otherwise mostly similar groups. Home ownership and the number of rooms used for sleeping are commonly used as proxies for wealth,12 and age of head of household was selected to assess demographic balances between the two groups. Income from earnings and other sources was used to assess the differences in the sources of household income. Income from social security was collected to assess the role that Instituto Nicaraguense de Seguridad Social (INSS) payments play in assisting CKDnt households in maintaining some rough economic parity with non-CKDnt households.

Table 1

Key demographic, income, earnings, employment and widowhood findings

Results

Table 1 illustrates some of the key findings from the study.

Despite demographic similarities, households with CKDnt differ in terms of the percentage of household heads who are unemployed compared with households without CKDnt (86% and 53%, respectively), and while the median total annual household income appears to be the same for both household types, this is explained by the substantially higher social security (INSS) payments received by CKDnt households as compared with non-CKDnt households. CKDnt households spend substantially more on medicine each month than non-CKDnt households. With regard to widowhood, 13% of the heads of household in our sample indicated that they were widowed (compared with the national rate of 5.5%13), and 80% of these widows/widowers indicated that they were widowed due to CKDnt. The average age of those widowed by CKDnt was substantially lower than those widowed by causes other than CKDnt (59 years and 71 years, respectively).

Discussion

Our study measures the socioeconomic effect of CKDnt on households by comparing these households to similar households not affected by CKDnt. Despite strong similarities in terms of demographic characteristics and despite residing in the same communities with similar access to available resources, households experiencing CKDnt exhibit distinct differences in important socioeconomic outcomes when compared with non-CKDnt households.

One potential explanation for the significantly lower percentage of female-headed households among CKDnt households may be because the male remains the head of household, despite being ill with CKDnt. Our finding of 40% of non-CKDnt households headed by women is substantially higher than the most recent Nicaraguan Demographic and Health Survey14 finding of 31%, perhaps reflecting the higher percentage of widowhood in the region than nationally. The removal of the male primary wage earner in our study communities may compound existing economic disadvantages experienced by women who typically enter the labour market to replace lost income.

Families affected by CKDnt bear substantial economic burdens. Approximately 15% of CKDnt households remove children from school to make up lost income.15 The state bears a large part of the costs of supporting those who have lost someone due to CKDnt through INSS payments to CKDnt households. These payments enable CKDnt households to maintain a rough parity in terms of income with non-CKDnt households. It is unlikely that the burden of caring for workers suffering from the disease is sustainable, pointing to the need for increased surveillance of labour practices and the implementation of effective interventions. By our estimate of the community prevalence and the per household INSS payments provided to affected households, the state makes annual expenditures of approximately $C48 000 (or US$1355) per household.

A second round of data collection from baseline households was completed in 2022. Forthcoming analyses will examine changes over time in the resulting panel dataset with respect to income, earnings and household resilience.

Data availability statement

Data are available on reasonable request.

Ethics statements

Patient consent for publication

Ethics approval

This study involves human participants and the University of Texas at Austin IRB has issued an 'IRB Exempt Determination for Protocol Number 2020-03-0078'. Participants gave informed consent to participate in the study before taking part.

References

Footnotes

  • HP and TB contributed equally.

  • Contributors HP, TB and AP performed statistical analyses, drafted the manuscript. JG, CW and WM-C contributed to drafting the article and critically revising it. All authors gave final approval for the version to be submitted. HP is responsible for the overall content as guarantor and accepts full responsibility for the finished work, and/or the conduct of the study, had access to the data and controlled the decision to publish.

  • Funding The study was internally and jointly funded by the US National Science Foundation and the US National Oceanic and Atmospheric Administration, grant/award number 2017885.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.