Evaluation of the Diagnostic Utility of Urine Biomarkers Tissue Inhibitor of Metalloproteinases-2 (TIMP-2) and Insulin-like Growth Factor Binding Protein-7 (IGFBP-7) in Predicting Acute Kidney Injury and Short-term Outcomes among High-risk, Critically Ill Patients in a Tertiary Government Hospital in the Philippines.

Backgroundandobjectives: Acute kidney injury (AKI) is a common complication of critical illness that often leads to increased mortality and morbidity. Biomarkers detect AKI earlier, providing a window of opportunity for timely intervention. Of the recent biomarkers in literature, the cell cycle arrest biomarkers tissue inhibitor of metalloproteinases-2 (TIMP-2) and insulin-like growth factor binding protein-7 (IGFBP-7) were found to be superior in predicting AKI. Our study aimed to evaluate the diagnostic performance of urine TIMP-2/IGFBP-7 in its ability to predict AKI and major adverse kidney events within 30 days (MAKE30) among high-risk patients for AKI. MAKE30 is a composite outcome comprised of all-cause mortality, use of renal replacement therapy (RRT), or persistent renal dysfunction at hospital discharge truncated at 30 days.

Methods: We conducted a prospective, cross-sectional study which included 135 adult, non-COVID ICU patients. Baseline urine TIMP-2/IGFBP-7 results were used to dichotomize the population into low risk (<0.3 ng/mL) or high risk (≥0.3 ng/mL) for AKI. Participants were then observed for 30 days and monitored for MAKE30 outcomes. ROC curves were created to calculate the sensitivity, specificity, NPV, PPV, and the AUC of the 0.3 ng/mL cut-off to predict the AKI and MAKE30.

Results: Urine TIMP-2/IGFBP-7 cutoff of 0.3 ng/mL predicted AKI with a sensitivity of 82.4%, specificity of 79.2%, PPV of 57.1%, NPV of 93% and AUC of 0.81. MAKE30 was detected with a sensitivity of 62.8%, specificity of 76.1%, PPV of 55.1%, NPV of 81.4% and AUC of 0.69. Elevated levels of urine TIMP-2/IGFBP-7 were found to be associated with AKI (p<0.01), MAKE30 (p<0.01) and all of its subcomponents. Survival or discharge after 30 days were found to be associated with lower urine TIMP-2/IGFBP-7 levels (p<0.01).

Conclusions: Urine TIMP-2/IGFBP-7, at its current cut-off at 0.3 ng/mL, can predict the likelihood of developing AKI and major adverse kidney events among high-risk patients for AKI. It can serve as a useful adjunct to existing methods, such as serum creatinine, in the early diagnosis and prognosis of acute kidney injury and expanding the therapeutic window to prevent disease progression and improve outcomes.