Chronic Kidney Disease of Unknown Etiology (CKDu) as an Underappreciated Cause of Emergent Hemodialysis Utilization in the United States
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Introduction
End stage kidney disease (ESKD) affects an estimated 5500 persons living in the United States without legal residency documentation. One likely, but underappreciated cause of ESKD in the Hispanic migrant population, is chronic kidney disease of unknown etiology (CKDu). CKDu is an interstitial nephritis that disproportionately affects young adult agricultural workers in Central America who lack traditional risk factors for kidney disease. In underserved populations, such as those at risk for CKDu, substantial barriers to optimal kidney care translate to poorer health outcomes and widening health disparities. Without funding for non-emergent healthcare, this underserved population, often only have access to hemodialysis (HD) once a life-threatening condition occurs. Despite the presence of a migrant population from CKDu endemic countries and anecdotes of its presence, CKDu has very rarely been directly investigated or documented in the US. We undertook this study to establish the existence of CKDu in the United States and to characterize CKDu as a cause of ESKD in patients accessing emergent HD.
Methods
In a retrospective cross-sectional study among patients receiving emergent HD in Texas, we analyzed medical record data from a large, county hospital. We ascertained cause of ESKD and underlying hypertension and diabetes and compared these proportions to data on patients on maintenance HD from the US Renal Data System (USRDS). Undocumented immigrants are largely excluded from the USRDS, as with many health statistics databases in the US. We identified patients whose clinicians had indicated CKDu as a diagnosis and classified others as having suspected CKDu or possible CKDu based on clinically informed criteria.
Results
We identified 346 patients with ESKD requiring emergent HD (2012-2015), who were younger than patients in the USRDS (median age 52 yrs vs. 61 yrs, p <0.001), had more comorbid diabetes (60% vs. 47%, p <0.001), and more often had an unknown cause of ESKD (16% vs. 4%, p<0.001). Patients requiring emergent HD also had less frequent arteriovenous access (12% vs. 82%, p<0.001). ESKD attributed to diabetes and/or hypertension accounted for only 67% of emergent HD patients, compared to 81% of USRDS patients (p<0.001). 14% of the patients on emergent HD died during the study period. Four patients had been clinically diagnosed with CKDu, while we classified 14 with suspected CKDu and 40 with possible CKDu, for a total of 58 patients (17%) with potentially CKDu-related ESKD.
Conclusion
Our analysis suggests that up to 17% of patients in this population utilizing emergent HD had CKDu-related ESKD, suggesting that CKDu is likely underdiagnosed in the US. Further, patients receiving emergent HD were younger but were at higher risk of infection or complication than patients receiving scheduled, maintenance HD. Understanding CKDu and improving access to scheduled dialysis for migrants without legal residency documentation should be prioritized to reduce stress on the healthcare system and improve health among vulnerable populations in the US.
