Seasonal differences in the risk of acute kidney injury (AKI) and the effect of season on the associations between core temperature and AKI and between work intensity and AKI, among heat-exposed Florida agricultural workers Open Access

Obadina Itunuola, Catherine (Spring 2019)

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Introduction.  Acute kidney injury (AKI) can result in a number of complications such as chronic kidney disease, end-stage renal disease, and death. Exposure to heat has been associated with AKI. There is, however, a limited understanding on how different seasons affect the incidence of AKI and how season modifies the association between core temperature and AKI, and work intensity and AKI among heat-exposed agricultural workers.

Methods. Physiological data along with blood and urine samples were collected from 245 agricultural workers employed in various agricultural industries in different communities in Central Florida. Data were collected during 3-day work periods in the summer of 2016 (n=183) and winter of 2017 (n=62). Pre- and post-shift samples were collected on each workday. Chi-square test was used to compare the risk of AKI across seasons while stratified logistic regression and interaction terms were used to examine the effect of core temperature and work intensity on the risk of AKI and potential modification of these effects by season.

Results. Among summer participants, 32% had a form of AKI on at least 1 workday as compared to 17% of winter participants (p=0.18); 28% of participants in the summer had stage 1 AKI on at least 1 workday compared to 12% in the winter. In the summer season, after adjusting for age and sex, the risk of developing AKI in agricultural workers with core temperature ≥38°C was 72% higher than the odds in those with core temperature <38°C (OR, 1.72; CI, 1.20-2.46). In the logistic regression models examining the effect of the interaction between work intensity and season on AKI as well as the effect of the interaction between core temperature and season on AKI, there were no seasonal differences in the associations between Core temperature and AKI (p=0.27) or work intensity and AKI (p=0.63) when adjusted for age, sex and other covariates.

Conclusions. There was no significant difference in the risk of AKI across seasons and the associations between work intensity and AKI as well as core temperature and AKI did not differ significantly by season.


Table of Contents

Introduction --------------------------------------------------------------------------- 1

Methods ------------------------------------------------------------------------------- 2

         Study design and population ----------------------------------------------------- 2

         Data collection and kidney function indicator ------------------------------------ 3

             Outcome - AKI ----------------------------------------------------------------4

            Exposures-Core temperature and Work intensity -----------------------------5

         Statistical analysis ----------------------------------------------------------------5

Results --------------------------------------------------------------------------------- 6

Discussion ----------------------------------------------------------------------------- 8

References ----------------------------------------------------------------------------- 12

Tables --------------------------------------------------------------------------------- 15

        Table 1a ---------------------------------------------------------------------------15

        Table 1b --------------------------------------------------------------------------- 16

        Table 2 ---------------------------------------------------------------------------- 17

        Table 3 ---------------------------------------------------------------------------- 18

        Table 4 ---------------------------------------------------------------------------- 18

        Table 5 ---------------------------------------------------------------------------- 19

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