Levels of plasma kidney injury molecule-1 (KIM-1) are associated with diagnoses, pathologic findings, and kidney failure risk in patients with a wide range of kidney disease diagnoses, according to a report in the American Journal of Kidney Diseases.
The analysis included participants in two prospective, observational cohort studies: 524 patients undergoing clinically indicated native kidney biopsy enrolled in the Boston Kidney Biopsy Cohort (BKBC) and 3800 patients with common types of chronic kidney disease (CKD) from the Chronic Renal Insufficiency Cohort (CRIC) study. Baseline plasma KIM-1 levels were analyzed for association with subsequent kidney failure (defined as initiation of dialysis) and death.
In multivariable analyses of BKBC participants, higher plasma KIM-1 levels were associated with more severe acute tubular injury, tubulointerstitial inflammation, and more severe mesangial expansion. By diagnosis, plasma KIM-1 levels were higher in patients with diabetic nephropathy, glomerulopathies, and tubulointerstitial disease.
In BKBC, during a median follow-up of 5 years, 124 patients progressed to kidney failure, and 85 died. For each doubling of baseline plasma KIM-1, hazard ratio (HR) for kidney failure was 1.19. Plasma KIM-1 was not significantly associated with mortality after multivariate adjustment.
In the CRIC study, higher plasma KIM-1 was associated with non-White race, higher prevalence of diabetes and cardiovascular disease, higher systolic blood pressure, and lower hemoglobin. Plasma KIM-1 was negatively correlated with estimated glomerular filtration rate and positively correlated with urinary albumin-to-creatinine ratio.
At a median follow-up of 11.5 years in CRIC, 1153 patients had progressed to kidney failure, whereas 1356 died. For each doubling of plasma KIM-1, HR for kidney failure was 1.10. In the highest quintile of plasma KIM-1, HR for progression was 1.58. Again, there was no significant association with mortality.
Plasma KIM-1 is a sensitive marker of tubular injury, which may contribute to development or progression of CKD. The new analysis finds that higher plasma KIM-1 is associated with tubulointerstitial and mesangial lesions and is an independent risk factor for progression to kidney failure. The investigators conclude: “Collectively, the findings suggest that plasma KIM-1 may serve as a non-invasive tool to assess histopathologic lesions and has prognostic value across a variety of kidney diseases” [Schmidt IM, et al. Plasma kidney injury molecule 1 in CKD: Findings from the Boston Kidney Biopsy Cohort and CRIC studies. Am J Kidney Dis, published online ahead of print June 24, 2021. doi: 10.1053/j.ajkd.2021.05.013; https://www.ajkd.org/article/S0272-6386(21)00694-6/fulltext].