Unadjusted point of care creatinine results overestimate acute kidney injury incidence during field testing in Guatemala

Abstract

ObjectiveAcute kidney injury (AKI) occurs at high rates among agricultural workers (12–33%) in tropical environments. Because of the remote locations affected, traditional laboratory services are often unavailable. In this study we compare point of care (POC) creatinine values to standardized laboratory values, and examine the effect of POC testing on the interpretation of AKI rates under tropical field conditions.MethodsBlood samples were collected from 104 sugarcane workers from two time points in January 2018 as a derivation cohort, and from 105 workers from February to April 2017 as a validation cohort. Finger stick and venipuncture samples were drawn at the end of a worker’s shift to measure creatinine. Laboratory samples were tested in Guatemala City, Guatemala, in duplicate using the Jaffe Generation 2 method. An adjustment factor to improve agreement with serum creatinine was statistically derived and validated, and then used to determine impact on observed rates of acute kidney injury based on across shift changes in creatinine.ResultsPOC creatinine and serum creatinine measures showed that POC consistently overestimated the creatinine by an average of 22% (95% CI: 19.8%, 24.7%) and the disagreement appeared greater at higher values of serum creatinine. An adjustment factor of 0.7775 was applied, which led to significantly greater agreement between the two measures. Rates of AKI in the two combined groups fell from 72% before adjustment to 57% afterwards.ConclusionsPOC testing under tropical field conditions routinely overestimates creatinine compared to laboratory testing, which leads to overestimation of rates of acute kidney injury. The application of an adjustment factor significantly improved the accuracy of the POC value.

Acute kidney injury and workload in a sample of California agricultural workers

“…A final limitation is the potential for error in our estimates of AKI based on a point‐of‐care test of serum creatinine. A recently published study reported that point‐of‐care testing may overestimate creatinine levels . While this is a significant potential limitation in our data, other studies of AKI in agricultural workers find similar results using different assessment methods.…”

Hydration Choices, Sugary Beverages, and Kidney Injury in Agricultural Workers in California

“…However multiple studies of kidney injury in Central America have reported that persons with AKI continued to have decreased kidney function when assessed months later (Kupferman et al, 2018; Wesseling, Aragón, González, Weiss, Glaser, Bobadilla, et al, 2016), suggesting that the AKI that occurs in the work shift may be a precursor to more chronic damage. It is also important to note that creatinine is not always a reliable marker of actual injury to the kidneys (Griffin et al, 2018); however, in field studies with agricultural workers, its ease of use and relatively noninvasive methods of collection make it the most feasible measure.…”

Longitudinal trends in renal function among first time sugarcane harvesters in Guatemala

“…The Creatinine Jaffe Generation 2 method was used to determine serum creatinine. Further detail on the laboratory methods has been published elsewhere [21]. The primary outcome was the pattern of change in estimated glomerular filtration rate (eGFR) over a period of up to 4 years (2012-2016).…”