An ecological study of chronic kidney disease in five Mesoamerican countries: associations with crop and heat

Erik Hansson,Ali Mansourian,Mahdi Farnaghi,Max Petzold,Kristina Jakobsson

doi:10.1186/s12889-021-10822-9

Abstract

BackgroundMesoamerica is severely affected by an epidemic of Chronic Kidney Disease of non-traditional origin (CKDnt), an epidemic with a marked variation within countries. We sought to describe the spatial distribution of CKDnt in Mesoamerica and examine area-level crop and climate risk factors.MethodsCKD mortality or hospital admissions data was available for five countries: Mexico, Guatemala, El Salvador, Nicaragua and Costa Rica and linked to demographic, crop and climate data. Maps were developed using Bayesian spatial regression models. Regression models were used to analyze the association between area-level CKD burden and heat and cultivation of four crops: sugarcane, banana, rice and coffee.ResultsThere are regions within each of the five countries with elevated CKD burden. Municipalities in hot areas and much sugarcane cultivation had higher CKD burden, both compared to equally hot municipalities with lower intensity of sugarcane cultivation and to less hot areas with equally intense sugarcane cultivation, but associations with other crops at different intensity and heat levels were not consistent across countries.ConclusionMapping routinely collected, already available data could be a first step to identify areas with high CKD burden. The finding of higher CKD burden in hot regions with intense sugarcane cultivation which was repeated in all five countries agree with individual-level studies identifying heavy physical labor in heat as a key CKDnt risk factor. In contrast, no associations between CKD burden and other crops were observed.

Highlights

Mesoamerica is severely affected by an epidemic of Chronic Kidney Disease of non-traditional origin (CKDnt), an epidemic with a marked variation within countries
We modelled the age-standardized chronic kidney disease (CKD) mortality rate for working-age (20–50 years in Costa Rica and Guatemala, 18–60 years in Mexico) men and women separately using Poisson regression, but exceptions had to be made for Nicaragua and El Salvador
Sugarcane was the only crop which in all countries was associated with a higher CKD burden when intensely rather than sparsely cultivated in such heat (CKD burden ratios at least doubling in all countries, increasing from approximately 1–3 to 2–9 in all countries), but there was no such clear CKD burden increase when sugarcane was intensely cultivated in less hot regions (CKD burden ratios at 1–2 in all countries) (Fig. 2)

Summary

Introduction

Mesoamerica is severely affected by an epidemic of Chronic Kidney Disease of non-traditional origin (CKDnt), an epidemic with a marked variation within countries. One study identified cultivation of other crops; cotton, coffee, corn and beans as an area level risk factor, albeit at a smaller extent [6] The former finding is congruent with the high rate of kidney injury [7,8,9,10,11,12,13,14,15] and high prevalence of CKDnt among sugarcane workers in coastal regions [5, 16], but not in highland areas [5], Hansson et al BMC Public Health (2021) 21:840 which has led to the hypothesis that CKDnt is caused by repeated excessive heat exposure [17, 18]. The latter finding of associations with other crops was interpreted as in line with another hypothesis of the underlying cause of CKDnt - pesticide exposure [6]

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Results

Discussion

Conclusion