Scoping Review of Interventions to Prevent CKD of Unknown Origin in Working Populations

Abstract

Introduction

Chronic kidney disease (CKD) of unknown origin (CKDu) is a form of progressive kidney damage not attributable to traditional causes of CKD that has been observed primarily among agricultural workers in Central America and South Asia. The causes of CKDu remain an area of ongoing research. This scoping review aimed to summarize interventions used to prevent CKDu in working populations and to propose a comprehensive framework for future interventions.

Methods

A literature search across multiple databases was conducted on August 16, 2024 with an update on November 12, 2025. Articles that met the inclusion criteria were systematically assessed for quality, key elements of the interventions were extracted, and intervention quality was evaluated by 2 independent reviewers with a third serving as tiebreaker. Studies were graded using the Effective Public Health Practice Project (EPHPP) tool. Eight domains were used to evaluate intervention quality.

Results

Eight articles met the final inclusion criteria. Four articles were graded as weak, 3 as moderate, and 1 as strong global quality. The interventions generally addressed water, rest, and shade (WRS). Most interventions addressed only 1 intervention quality domain, adoption. Few interventions addressed the domains of acceptability, appropriateness, cost, feasibility, fidelity, or penetration. No interventions addressed sustainability.

Conclusion

Few workplace interventions have been studied for their ability to prevent CKDu. Interventions that focused on WRS showed promising evidence for reducing CKDu incidence and progression, despite study quality concerns. The intervention studies were generally lacking in most domains of successful public health interventions.

Graphical abstract

CKDu is a form of progressive loss of kidney function not attributable to traditional causes of CKD such as hypertension, diabetes mellitus, infectious diseases, or the aging process.¹ CKDu has been best studied in and is known to be endemic to Central America and South Asia, particularly Sri Lanka and India. Pockets of the disease have been reported in Egypt and the United States.^2,3 In addition, CKDu has been predominantly observed in agricultural communities, with the prevalence of CKDu differing between occupations and job duties. For example, CKDu prevalence is high among sugarcane cutters. In addition, the disease has been described in cotton, corn, and shrimp farm workers as well as in industrial settings such as construction sites and mines.³

The global burden of CKD of all etiologies has been reported to be increasing over time with an estimated 843.6 million total individuals affected by CKD worldwide.^4,5 CKD has a high mortality rate and was one of the top 10 leading causes of death globally in 2021.4, 5, 6 Although the proportion of CKD attributable to CKDu has been difficult to quantify on a global scale, in-part because of considerable variability in diagnostic criteria used to define CKDu,⁷ CKD prevalence among communities determined to be at high risk of CKDu has been estimated to be between 6% and 17% in Sri Lanka8, 9, 10 and 2% and 50% in Nicaragua and El Salvador.11, 12, 13, 14, 15, 16 Moreover, given the asymptomatic nature of CKD until late stages of disease and challenges related to health care access among rural communities, CKDu prevalence may be significantly underestimated.¹⁷

In addition to occupation, identification of other risk factors for developing CKDu is an area of active research. Current consensus is that CKDu is a complex, multifactorial disease influenced primarily by environmental factors that may include heat, physical job demands, dehydration, water sources, heavy metals in the environment, and exposure to agrochemicals.^1,18,19 In addition, genetic polymorphisms have been proposed as a predisposing factor.^1,20

As the research community strives to better understand the characteristics and causes of this disease process, affected communities and individuals remain at risk. Therefore, there is a need for the development and implementation of intervention strategies to address known risk factors while concurrently exploring the full etiology of disease.^19,21 Moreover, in the context of evidence-based health interventions, it is critically important to evaluate each intervention’s implementation and efficacy. Implementation outcomes aim to characterize the effect of the implementation strategies whereas efficacy outcomes are more concerned with the overall impact of the intervention on the target population.²² This is a key concept from the field of dissemination and implementation (D&I) science in occupational safety and health (OSH) where there has historically been a disconnect between research and implementation of practices that protect workers.²²

Workplace interventions are central to addressing CKDu. Occupation, specifically working in agriculture, is a well-established risk factor for the development of CKDu.^1,3,16,18,19 Considering that agricultural workers are at risk of developing CKDu likely because of the nature of their work, it is prudent to design interventions that can be implemented in the workplace setting to reduce the risk of development and/or progression of CKDu. Furthermore, this is relevant not only for the health and safety of the workers, but also for the economic benefit of employers and employees. Workers who have dropped out of intervention studies have been found to have higher rates of kidney injury, supporting the thesis that this disease process may be directly contributing to job loss and decreased productivity.^23,24

This scoping review aimed to summarize and evaluate published workplace interventions in which investigators implemented protocols to prevent CKDu. Furthermore, we propose a comprehensive framework that could be applied in future intervention studies using concepts derived from D&I science.

Methods

A scoping review was conducted to summarize and evaluate workplace interventions that have been implemented related to CKDu. The primary goals were to:

• 1.Identify and summarize the characteristics of studies describing workplace interventions that aimed to prevent the development or progression of CKDu.
• 2.Evaluate and summarize the quality of the studies that have implemented these interventions.
• 3.Evaluate the extent to which the studies applied and documented adherence to fundamental concepts from D&I science.

Initial Search

The methodology for this scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklists and guidance.^25,26 A protocol was developed by the research team before the study. The protocol was not registered with a particular entity. During initial review of the articles, minor modifications to the exclusion criteria were made. The literature search was conducted on August 16, 2024 with an update on November 12, 2025. The search strategy was designed in partnership with a librarian (BH) to identify published studies on workplace interventions designed to prevent the development or progression of CKDu. To assist in the development of the search strategy, a brief literature review was conducted to identify alternative terms used to describe the disease process of CKDu. CKD of uncertain etiology, Central American nephropathy, and Mesoamerican nephropathy are a few examples of other terms we found used to describe CKDu in the literature.

The initial search was broad and included all identified terms for CKDu. The Complete Search Strategy for the full search strategy, including the specific alternative names for CKDu that were used are presented in the Supplementarty Material. The following databases were queried (dates are for the update): Ovid MEDLINE(R) ALL (1946–November 11, 2025); Embase (Embase.com, 1974–November 12, 2025); Web of Science Core Collection (1974–November 11, 2025); Cochrane Central (Cochrane Library, Wiley); American Psychological Association PsycInfo (Ovid, 1806–November 11, 2025); CINAHL: Cumulated Index to Nursing and Allied Health Literature (EBSCO, Elton B. Stephens Company, 1981–November 11, 2025); and Google Scholar (August 16, 2024; first 100 citations) retrieved via Harzing, A.W. (2007) Publish or Perish, available from https://harzing.com/resources/publish-or-perish. Google Scholar was not searched for the update. Conference abstracts or papers were limited to the last 3 years in Embase. No other limits were applied.

Study Selection

As shown in Figure 1, a total of 8664 citations were retrieved. All records were deduplicated and organized using the citation management software, EndNote version 21. After manual deduplication using EndNote, 3819 total citations were uploaded to Covidence, a systematic review citation reviewing and screening software. Covidence detected 26 additional duplicates, and 8 duplicates were identified and removed during screening, which resulted in 3785 citations moving on to the initial title and abstract screening. Titles and abstracts were screened by 2 independent reviewers (EB and APDOP), with a third reviewer (LSN) as tiebreaker for any disagreement. Inclusion criteria at this stage were for the article or abstract to be about CKDu (or other names for the same condition) and to include some kind of intervention for primary, secondary, or tertiary CKDu prevention. This resulted in 271 articles moving to the full article review stage.

Figure 1.

PRISMA flow chart outlining study selection strategy. See Supplementary Complete Search Strategy for the full search strategy. CKDu, chronic kidney disease of unknown etiology; PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

A single independent reviewer (LSN) conducted the full article review. Any articles where there may have been a question about whether they should be included during the full text review were marked and reviewed by a second independent reviewer (MD). After the second independent review, no additional modifications were deemed necessary. During the full article review stage, 263 articles were excluded because they did not meet the final inclusion criteria of describing the results of an intervention that aimed to prevent CKDu development or progression among working populations. The full Preferred Reporting Items for Systematic Reviews and Meta-Analyses²⁵ diagram and detailed reasons for inclusion and exclusion at each stage are presented in Figure 1. The process resulted in selecting 8 final articles for data extraction.

Data Extraction and Synthesis

Data were extracted in 3 phases. In the first phase, 2 independent reviewers from the research team (AD-R and DJ) extracted data related to the study. Both reviewers extracted data from all 8 articles. In the case of discrepancies, a third reviewer (MD) acted as a tie breaker. These data included items such as study design, study population, intervention components, measured outcomes, and findings (Table 1).27, 28, 29, 30, 31, 32, 33, 34, 35

Table 1.

Article and intervention characteristics for all included articles

Author, Year	Article Title	Study Design	Country (WBIC)	Population // Comparison Group	Exclusion Criteria	Intervention Components	Outcomes Measured	Findings
Bodin et al.27	Intervention to Reduce Heat Stress and Improve Efficiency Among Sugarcane Workers in El Salvador: Phase 1	Cohort	El Salvador (upper middle income)	Sugarcane harvesters (n = 116) // Self (preintervention)	Not reported	Water, rest, and shade. Workers were provided with 3 L water backpacks, access to water refills, and a mobile shade tent. Workers were given 10–15 min rest breaks every 1–1.5 h. The workers were also given lighter machetes with ergonomic handles.	Heat exposure, production change, symptoms of heat stress, qualitative evaluation of the intervention	The intervention increased water consumption, increased productivity, workers responded positively to shade, and qualitative analysis revealed positive attitudes about the intervention generally.
Wegman et al.28	Intervention to Diminish Dehydration and Kidney Damage Among Sugarcane Workers	Cohort	El Salvador (upper middle income)	Sugarcane harvesters (n = 80) // Self (preintervention)	Not reported	Water, rest, and shade. Workers were provided with 3 L water backpacks, access to water refills, and a mobile shade tent. Workers were given 10–15 min rest breaks every 1–1.5 h. The workers were given lighter machetes with ergonomic handles.	Cross shift eGFR, SCr, creatine phosphokinase, albumin, uric acid, and urea nitrogen, and urine osmolality	The intervention had a positive effect on both cross shift and cross harvest kidney function.
Hansson et al.29	Workload and Cross-Harvest Kidney Injury in a Nicaraguan Sugarcane Worker Cohort	Cohort	Nicaragua (lower middle income)	Sugarcane harvesters (n = 348), drip irrigation repair workers (n = 128), field support staff (n = 54) // Self (preintervention)	Males with SCr > 1.3 and females with SCr > 1.0	Preemployment health screening. Men with SCr < 1.3 and women with SCr < 1.0 were hired.	Incident kidney injury, cross harvest change in eGFR	Physically demanding job tasks were associated with kidney injury.
Sorensen et al.30	Workplace Screening Identifies Clinically Significant and Potentially Reversible Kidney Injury in Heat-Exposed Sugarcane Workers	Cohort	Guatemala (upper middle income)	Male sugarcane harvesters (n = 92) // Workers with normal kidney function (eGFR of 90 or above) (n = 391)	eGFR < 60	Water, electrolytes, rest, and shade (WERS). Increased education on the importance of WERS and incentive of raffle tickets that were given if hydration was improved or maintained during the work shift.	Cross season changes in eGFR	Rate of eGFR change was improved after the intervention implementation.
Glaser et al.31	Preventing Kidney Injury Among Sugarcane Workers: Promising Evidence from Enhanced Workplace Interventions	Cohort	Nicaragua (lower middle income)	Sugarcane harvesters (n = 379) // 2017-2018 preintervention harvest season (n = 345, see Hansson et al.26)	Males with SCr > 1.3 or serum uric acid > 7.0. Females with SCr 1.0 or serum uric acid > 5.7.	Water, rest, and shade. More shade tents and different orientation as well as material of tent. Water and tents moved with the workers. Improved taste of hydration solution and increased attention to electrolyte use. Delayed cutting time to 12+ hours after burning. Reduced NSAID use.	Incident kidney injury	The intervention reduced kidney injury risk.
Lopez-Galvez et al.32	Longitudinal Assessment of Kidney Function in Migrant Farm Workers	Case-Control	Mexico (upper middle income)	Migrant and seasonal farm workers (MSFW) (n = 101) // Office workers (n = 50)	Workers who directly apply pesticides. Previous diagnosis of renal health issue, diabetes, or hypertension.	Reduced exposure to pesticides, heat, and dehydration.	Cross season changes in eGFR	MSFW groups had a significant kidney function decline compared to office workers. This effect was worse for those exposed to pesticides.
Amarasiri de Silva and Albert33	Kidney Disease, Health, and Commodification of Drinking Water: An Anthropological Inquiry into the Introduction of Reverse Osmosis Water in the North Central Province of Sri Lanka	Cohort	Sri Lanka (lower middle income)	Families in Medirigitiya (n = 200) // Self (preintervention)	Not reported	Provide reverse osmosis water filters for community water sources.	Changes in SCr, community member perception of reverse osmosis treated water	Switching to reverse osmosis water consumption improved SCr in CKDu patients.
Hansson et al.34	Rest, Shade, Hydration, and Hygiene for the Prevention of Kidney Injuries and Inflammation in a Nicaraguan Sugarcane Worker Cohort	Cohort	Nicaragua	Sugarcane workers working in the harvests from 2017 to 2021. The majority of participants were male and under the age of 45 yrs.	Before 2019: SCr < 1.3 mg/dl for men and < 1.0 mg/dl for women 2019/2020 harvest onward: eGFR < 90 ml/min per 1.73 m2 for both men and women Field support staff workers were also excluded because they could not be identified accurately.	The intervention was conducted in 4 stages over 4 harvest seasons. In harvest season 1: company’s existing practices (2–3 breaks/d) In Harvest season 2: 4 breaks per day and the company was given recommendations around shade, hydration, and latrine availability. In Harvest 3 and 4: 5–6 breaks/d	Changes in preharvest vs. postharvest serum creatinine and serum CRP, postharvest-leukocyturia, incident kidney injury (defined as an increase in sCr of 0.30 mg/dl or more across the harvest season), and change in eGFR (ΔeGFR).	Among male cutters, decreased rates of incident kidney injury, leukocyturia, serum CRP, and less pronounced declines in eGFR with the implementation of the rest, shade, hydration, and hygiene intervention between 2017-2021 with most significant results among the burned cane cutters. Among female workers, less change was observed. At the end of the harvest, leukocyruria decreased for seed cutters.

CRP, C-reactive protein; eGFR, estimated glomerular filtration rate; MSFW, migrant and seasonal farm workers; Scr, serum creatinine; WBIC, World Bank Income Classification.³⁵

In the second phase, data related to quality assessment were extracted (Figure 2). The data collection tool for the quality assessment was based on the EPHPP Quality Assessment Tool (QAT). The EPHPP QAT was developed with the purpose of creating a method to test and provide evidence to support public health interventions and research.³⁶ The EPHPP QAT evaluates public health interventions across the following 6 domains: selection bias, study design, confounding, blinding rating, data collection, and withdrawal or dropout and combines scores across each category to determine an overall rating of weak, moderate, or strong study quality. The EPHPP QAT has content and construct validity^37,38 and has been determined to be appropriate for systematic reviews of intervention efficacy.³⁹ As with the first phase of data extraction, 2 reviewers (EB and PHO) independently extracted data from all 8 articles with a third reviewer (AD-R) reconciling differences.

Figure 2.

Summary of study quality assessment for each article using the Effective Public Health Practice Project Quality Assessment Tool.

In the third phase, we assessed the 8 articles for essential implementation measures from D&I science in OSH (Table 2).^22,40 Proctor et al.³² developed a framework with 8 implementation outcomes that are frequently used in public health intervention evaluation; these include acceptability, adoption, appropriateness, cost, feasibility, fidelity, penetration, and sustainability.^22,32 More details on each domain is included in Table 2 and Supplementary Table S1. Using the framework by Guerin et al.²² and Proctor et al.,⁴⁰ 2 independent reviewers (MD and DJ) extracted data with a third (LSN) acting as a tiebreaker.

Table 2.

Summary of the quality assessment of each intervention according to essential measures identified from dissemination and implementation science in OSH¹⁸

Article, Year	Acceptability	Adoption	Appropriateness	Cost	Feasibility	Fidelity	Penetration	Sustainability
	Did the authors describe if the intervention was agreeable or satisfactory?	Did the authors describe the uptake of the intervention (i.e. how many participants out of how many eligible)?	Did the authors describe the fit of the intervention within the setting?	Did the authors describe the cost of the intervention?	Did the authors describe the extent to which the intervention can be used within the setting?	Did the authors describe if/how the intervention was changed?	Did the authors describe if/how the intervention became integrated within the setting?	Did the authors describe if the intervention has been maintained?
Bodin et al.27	+a	+	+	-	-	-	+	-
Wegman et al.28	+	+	-	-	-	-	-	-
Hansson et al.29	-	+	-	-	-	-	-	-
Sorensen et al.30	-	+	-	-	-	-	-	-
Glaser et al.31	-	+	-	-	-	+	-	-
Lopez-Galvez et al.32	-	+	-	-	-	-	-	-
Amarasiri de Silva and Albert33	+	+	+	+	+	+	-	-
Hansson et al.34	+	-	+	-	+	+b	+	-

^a+ symbol represents “yes, this area was addressed in the study;” - symbol represents “no, this area was not addressed in the study.”

^bLimited, based on the fact that the study showed changes in the intervention across the harvest years, comparing the original intervention to the final intervention.

Results

Characteristics of Articles and Interventions

Of the 8 articles that met the inclusion criteria, 7 were cohort studies. The studies were primarily conducted in Latin America (El Salvador, Nicaragua, Guatemala, and Mexico) and 1 study was conducted in Sri Lanka. Participants in the included studies were primarily agricultural workers, with a specific focus on sugarcane workers. The most common intervention components included modifying the quality and availability of WRS. Methods for improving the quality and availability of water used for consumption included treatment of community water sources with reverse osmosis, providing filtered water, and more convenient access to water with a refillable backpack, and/or closer location of filtered water refill stations.^27,28,30, 31, 32, 33, 34 In addition, interventions typically included a component of community education about concerns related to water contamination, possible health effects, and the benefits of consuming filtered water. Although most interventions were implemented in the workplace,27, 28, 29, 30, 31, 32^,34 the implementation of reverse osmosis filters for community water sources was carried out in the agricultural community setting.³³ These studies generally found that increasing access to clean water, shade, and rest breaks reduced the risk of kidney function decline for study participants. In Table 1, we present an overview of each of the 8 included studies.

Impact of the Interventions

Generally, the impact of workplace interventions implemented to reduce the onset or progression of CKDu were assessed by examining cross shift and cross season changes in estimated glomerular filtration rate (eGFR) by measuring serum creatinine,28, 29, 30, 31, 32, 33, 34 Bodin et al.²⁷ evaluated the impact of their intervention by measuring heat exposure; workers’ behavior, including water consumption and productivity; symptoms of heat stress, and attitudes regarding the intervention from participants.

Bodin et al.²⁷ showed that, after their WRS intervention was implemented, self-reported water consumption increased by 25%, symptoms associated with heat stress and dehydration decreased, and daily production for each individual increased by about 30%. Overall, the participants generally regarded the impacts of the intervention as positive. Wegman et al.²⁸ showed a reduction of about 36% in cross-shift decrease in eGFR among individuals receiving the WRS intervention. Hansson et al.²⁹ found that, after they implemented preemployment screening of kidney function and tracking cross-harvest changes in eGFR, cross harvest kidney injury among sugarcane workers was observed in 2% of low-to-moderate workload jobs compared with 27% in the very high workload category. They demonstrated that even with preemployment screening for normal kidney function, kidney injury still occurred in participants and was higher in physically demanding roles.

Sorensen et al.³⁰ showed a significant improvement in preshift eGFR and slower rate of eGFR decline observed in workers with abnormal or reduced kidney function. Their data revealed stable eGFR among workers with normal kidney function after implementation of their WRS intervention. Glaser et al.³¹ demonstrated that implementation of their WRS was associated with a 70% decrease in cross-harvest kidney injury among burned cane cutters. Lopez-Galvez et al.³² revealed that migrant and seasonal farm workers exposed to pesticides had significantly larger declines in kidney function across the harvest than those working in organic fields. Moreover, office workers included as a control group did not experience a decline in eGFR over the harvest season. Amarisiri de Silva et al.³³ showed an improvement in community member kidney function after implementing reverse osmosis water filters throughout the community. Finally, Hansson et al.³⁴ demonstrated that after their WRS intervention was implemented, kidney injury rates decreased by 20% among burned cane cutters.

Quality of Studies

In Figure 2, we summarize the quality assessment of the studies meeting inclusion criteria. In general, the included studies were found to be of low-to-moderate quality.27, 28, 29^,31 Only 1 study met the criteria to be considered strong.³⁰ Most studies were of low-to moderate quality in the categories of selection bias, study design, blinding, and withdrawal and dropout. The study that was considered strong achieved a moderate-to-strong rating in each category, with particular strengths in reducing selection bias, accounting for confounding variables, having valid data collection methods, and accounting for the numbers of and reasons for withdrawal.³⁰ Specific interpretation of the results of each category rating are defined by the EPHPP QAT data dictionary included in the Supplementary EPHPP Data Dictionary.

Implementation Outcomes

In Table 2, we present the essential quality measures from D&I science in OSH for each study’s intervention.²² None of the final 8 studies included an intervention evaluation that addressed all key quality measures. Apart from the de Silva and Albert,³³ Bodin et al.,²⁷ and Hansson et al.³⁴ studies, most studies addressed 1 additional implementation outcome or no additional implementation outcomes beyond adoption. No study assessed sustainability of the intervention, only 1 study assessed cost,³³ only 2 studies examined the penetration^27,34 or feasibility,^33,34 3 studies assessed fidelity of the intervention^31,33,34 or appropriateness,^27,33,34 and 4 studies addressed acceptability of the intervention.^27,28,33,34

Discussion

This scoping review identified remarkably few interventions designed to address the prevention of CKDu in the workplace. Of the > 3000 peer-reviewed papers published over the past > 50 years, we found only 8 workplace intervention studies addressing CKDu prevention. The 8 studies suggest that interventions seeking to prevent development or progression of CKDu should include elements of ensuring worker access to filtered water, rest, shade; and based on 1 study, mitigating exposure to pesticides. However, even this conclusion is tempered by the generally low-to-moderate quality of the studies. Furthermore, though we found that all 8 studies evaluated efficacy of the intervention, few described or evaluated the implementation process, potentially limiting the reproducibility and generalizability to other settings and populations. We call on the CKDu research community to expand its focus on the design, implementation, and evaluation of high-quality workplace interventions that can support CKDu prevention efforts and policy recommendations. There is a need for intervention studies that move beyond testing efficacy of WRS.

Quality of Studies

There are many inherent challenges when studying working human populations, especially in low-resourced settings, that may influence study quality. Study design is challenging within workplaces. Although the highest quality of study design according to the EPHPP QAT³⁶ is considered a form of a randomized control trial or controlled cohort trial, these are often difficult to achieve in workplaces because of the needs and work organization of the participating businesses.^41,42 In addition, because workers are consented and participate in nonroutine activities performed throughout the day (e.g., taking breaks, using shade, and stopping to hydrate), it can be difficult to blind the study participants to their intervention group assignment. One approach to address this challenge and to strengthen the quality rating of studies is through blinding the outcome assessor whenever possible.

In this scoping review, we found that most studies reported enrolling study participants who were representative of the target population. However, sample sizes in each study were found to be relatively low, with studies having difficulty reaching participation levels > 80%. Coupled with each study occurring only at a single worksite, the generalizability of the findings of these studies may be called into question. Future studies should consider implementing interventions across workers in multiple organizations, across multiple job titles or tasks, and/or across multiple geographic locations to improve generalizability of study findings.

Withdrawal or drop-out can threaten the generalizability of study findings. This is especially true in working populations and the phenomenon of the “healthy worker effect,” wherein only the healthiest workers remain in the worker cohort at the end of the study. For example, in a study by Dally et al.,²⁴ workers who started the harvest with lower levels of kidney function were more likely to leave the workforce before the end of the harvest season. Comparisons between workers who remained in the study cohort and those who withdrew or dropped out are necessary for assessing the potential bias on observed effect sizes.

We noted that half of the studies did not address potential confounding when reporting their results. This is likely because the etiology of CKDu is still being investigated, resulting in some confounders not being accounted for. Moreover, confounders that are identified may include the worker’s behaviors not directly related to work, including home water source and consumption, alcohol consumption, tobacco use, and medication use, that are subject to reporting and recall bias. Confounders that have been controlled for in previous studies that should be considered in interventions to prevent CKDu in working populations include age, biological sex at birth, educational attainment, systolic blood pressure, body mass index, baseline eGFR, and home residence.^29,30,32

Quality of Interventions

Intervention development consists of 4 primary stages, namely, design, implementation, evaluation, and sustainability.^43,44 Often in OSH research, only reports of the design and evaluation make it to the published literature.²² Although the evaluation of efficacy and effectiveness are important cornerstones, if implementation outcomes are not assessed to contextualize the efficacy of findings, researchers and practitioners may be denied important information regarding the drivers of the intervention’s success. Understanding how or why an intervention worked is crucial when disseminating the intervention to new or additional settings.²²

Acceptability, appropriateness, and feasibility are 3 implementation outcomes that measure the fit of the intervention, for example, how likely workers will participate in the intervention and whether the intervention is too disruptive or impractical given the work setting. Focus groups, semistructured interviews, or surveys of the target worker population are common ways to solicit insight on the acceptability, appropriateness, and feasibility of a proposed intervention before implementation.^22,45 Qualitative and semiqualitative assessments can result in preemptive modifications to the proposed intervention.

Modification of the intervention components, or fidelity, is arguably one of the most important implementation outcomes. Understanding how well an intervention was adhered to is important for attributing efficacy. For example, Sorensen et al.³⁰ did not report on fidelity outcomes. Although the authors noted that “In addition to the study intervention, individual health interventions and education were provided to study workers in the abnormal kidney function group by the Pantaleon medical staff,” there is no mention of what the individual health intervention or education entailed and thus we are unable to evaluate how consistently these components were provided.

Even though workplace-based preventive OSH interventions have been shown to demonstrate a positive return on investment,46, 47, 48 we found only 1 CKDu intervention study³³ that reported on the cost of the intervention. Cost is an essential characteristic of an OSH intervention and is often the key factor in organizational leadership’s decision to move forward with an OSH intervention.^23,49,50

Our results were concordant with these gaps described in the scientific literature regarding OSH interventions. The fact that none of the studies in our scoping review addressed intervention sustainability and that most of the studies in our scoping review only evaluated the intervention’s adoption suggests the need for a more systematic approach to developing, applying, and evaluating interventions to prevent CKDu in working populations.

A Proposed Framework for Future Interventions

By applying the core principles of implementation science when designing and evaluating public health interventions that address CKDu, investigators can accelerate our ability to find effective preventive workplace strategies. In addition, by including implementation science principles, interventions will have a higher likelihood of being sustained over time and generalizable to more than a single workplace or industry.²² This would help accelerate the translation of research into practice.⁵¹

In Figure 3, we propose a checklist to be used as a comprehensive framework for interventions that aim to prevent the onset or progression of CKDu in at-risk working populations based on the intervention quality concepts covered in Figure 2 from the EPHPP QAT³⁶ and the key implementation outcomes in Table 2 identified by Guerin et al.²² and Proctor et al.⁴⁰ summarized in Supplementary Table S1. These elements of intervention design, implementation, evaluation, and sustainability echo previous methodological recommendations for OSH interventions.^22,52,53 We opted for the format of a checklist without additional detail to account for the highly variable and context-dependent nature of OSH interventions, and to encourage customization required by the context.

Figure 3.

Proposed checklist to be used as a comprehensive framework of implementing CKDu preventive interventions in working populations. CKDu, chronic kidney disease of unknown etiology. ∗Based on elements of the EPHPP QAT.³⁵ †Based on the domains described outlined by Guerin et al.²² and Proctor et al.⁴⁰ Please refer to Table 2 and Supplementary Table S1 for a full description of what each domain entails and the questions they seek to answer.

A notable challenge with implementing screening or surveillance programs in working populations to prevent the onset or progression of CKDu is that the detection of kidney injury or CKDu may lead to loss of work. As observed by Hansson et al.,²⁹ 32% of workers who dropped out of the study reported kidney injury. As a result, workers may be hesitant to participate in screening or surveillance programs because they may want to continue working or rely on the income and they would rather not know about developing kidney disease or they may want to hide the development of kidney disease from their employers. Thus, though CKDu preventive workplace interventions may help detect and prevent CKDu among workers, it may put them at risk of unemployment. It is important that future studies consider this socioeconomic impact on workers in the evaluation of a program’s efficacy and implementation quality, which could be included as a component of acceptability.

Limitations

There are several limitations to this study. First, there may be interventions being implemented within organizations or industries that are not published or that were not captured in our search. We strived to achieve a comprehensive search strategy by including a variety of unique terms that are used to describe CKDu and by conducting the search across 7 databases.

Another limitation of this study is that we only included articles in English and Spanish, which may have resulted in omission of eligible papers published in other languages. Furthermore, data extraction from each article, application of the EPHPP QAT criteria (Figure 2), and evaluation of each article across the 8 domains from D&I science (Table 2) are processes subject to bias and different interpretations across each reviewer. To mitigate bias, as described in the methods, 2 independent reviewers extracted data at each stage and a third independent reviewer served as a tiebreaker. Having a single full text reviewer is another limitation that may have introduced selection bias into our study; however, we tried to reduce selection bias at this stage by having the first reviewer flag any full texts where there may have been questions about the article meeting inclusion criteria. Flagged papers were then reviewed by a second research team member and disagreements were reconciled.

In addition, this scoping review only focused on interventions for prevention of CKDu and not interventions preventing acute kidney injury (AKI). Reviewing interventions for AKI in the workplace was outside the scope of this review. It is possible that interventions that reduce the risk of recurrent AKI may be a strategy for preventing CKDu, as some authors have suggested.⁵⁴ Moreover, repeated episodes of AKI are well-established as an independent risk factor for the development and progression of CKD.55, 56, 57 Further research is needed to establish if AKI-directed workplace interventions mitigate the long-term risk for CKDu as for other forms of end-stage kidney disease.³

As noted above, only one of the studies of CKDu prevention addressed the cost of the intervention. It is possible that intervention studies considered cost while evaluating nonhealth, economic outcomes. Unless CKDu was one of the study’s outcomes, research on productivity or on cost-effectiveness was considered outside of our scope.

A final limitation is that our review of the final 8 articles and CKDu preventive interventions were strictly based on the information provided by the authors in their article. We did not contact authors to determine if other quality measures were evaluated but omitted from the final text.

Conclusion

To our knowledge, this is the first study seeking to identify and summarize the quality of workplace interventions that have been implemented to prevent CKDu. Despite > 3000 papers in the scientific literature on CKDu, few workplace interventions have been implemented and evaluated beyond testing for efficacy. Interventions that have been evaluated focus primarily on hydration, rest, and shade, which show promising evidence for reducing CKDu incidence and progression, with the caveat that these studies were generally conducted in small populations and were overall of low-to-moderate quality. Evaluation of the intervention quality using key concepts from D&I science in OSH showed that the authors rarely addressed acceptability, appropriateness, cost, feasibility, penetration, fidelity, or sustainability. We have identified a critical need for interventions to prevent CKDu and propose that investigators apply a checklist that we hope will accelerate the discovery of effective, generalizable, and sustainable workplace solutions for CKDu.

Disclosure

All the authors declared no competing interests.

Supplementary Material

Supplementary File (PDF)

Supplementary Complete Search Strategy. Supplementary EPHPP Data Dictionary. Data Dictionary for each category and results interpretation. Available on publicly accessible site published by EPHPP.²¹Table S1. Examples of key implementation outcomes and occupational safety and health effectiveness outcomes, published by Guerin et al.¹⁸ based on work from Proctor et al.²⁵ Supplementary PRISMA Checklist.