Abstract 15934: Higher Midlife Serum Levels of Kidney-injury Molecule-1 (KIM-1) are Associated With Incident Fatal CHD Over Very Long-term Follow-up Among Men

Abstract

Introduction: Higher levels of kidney-injury molecule-1 (KIM-1) measured in urine are associated with presence and progression of acute renal disease. A recent study reported similar results for KIM-1 measured in blood. Hypothesis: We hypothesized that KIM-1 measured in stored serum from middle-aged men who participated in the Multiple Risk Factor Intervention Trial (MRFIT) would differentiate very long-term risk of fatal CHD vs. survival to a mean age of 80 over approximately 30 year follow-up. Methods: We conducted a nested case-control study within MRFIT, which in 1973-76 randomized 12,866 high risk but CVD free men ages 35-57 to risk factor intervention vs. usual care. Serum samples were collected at baseline and stored for future use. The trial concluded in 1982 but long-term mortality follow-up was ascertained through 2005 using the National Death Index. From MRFIT participants with stored serum from baseline, we sampled 100 men who died of CHD (mean age 47.3 at baseline and 73.9 at death), and 100 men who survived to 2005 (mean age =48.4 at baseline and 80.1 in 2005.) KIM-1 was assayed from stored serum samples using high sensitivity single-molecule counting technology (Erenna ® Immunoassay System, Singulex), with limit of detection (LoD)=0.5 pg/ml, and lower limit of quantification (LLoQ)=2.0 pg/ml. Results were compared between cases and controls using Wilcoxon rank tests and logistic regression. Results: Inter-assay %CVs were 8%. Median KIM-1 was higher for smokers vs. non-smokers and for men with vs. without hypertension, but was not associated with high cholesterol. KIM-1 was significantly higher in cases (183 pg/ml (IQR: 137-239) versus controls, (161 pg/ml (IQR:109-212), p=0.03; OR (95%CI)for Q4 versus Q1 was 2.26 (1.02 - 5.02) Adjusted for age and smoking the OR(95%CI) of fatal CHD for Q4 vs. Q1 was 2.34 (1.02- 5.37), and further adjusted for diastolic BP and serum cholesterol at baseline, was 2.0 (95% CI: 0.8-4.7). Conclusions: Higher serum KIM-1 levels at midlife were associated with a ∼2-fold increased risk of fatal CHD vs. survival over ∼30 years of follow-up. This is the first report of a longitudinal association of circulating KIM-1 levels with fatal CHD in long-term follow-up.