Is (TIMP-2)X(IGFBP7) an early renal biomarker for the prediction of acute kidney injury in aortic surgery? – Results from a single center observational study

Introduction Postoperative acute kidney injury (pAKI) is a typical complication after abdominal aortic repair (AAR) (1). Urinary insulin-like growth factor-binding protein 7 (IGFBP7) and tissue inhibitor of metalloproteinases-2 (TIMP-2) were shown to predict pAKI with good accuracy in various patient cohorts (2). In cardiac surgery, data is contradictory (3-5). Investigated cohorts, timing, and others may affect sensitivity/specificity (6). We investigated whether urinary (TIMP-2)x(IGFBP7) predicts pAKI in AAR. Methods Prospective, single center, observational study (NCT 03469765). Patients referred for AAR (open and endovascular interventions) were eligible. Exclusion criteria: patient unable to provide informed consent, age Results pAKI occurred in 31 of 93 (33%) patients (n=71 open surgery). (TIMP-2)x(IGFBP7) levels did not differ between patients with/ without pAKI on the first POD (median 0.39, interquartile range [IQR] 0.13-1.05 and 0.23, IQR 0.14-0.53, p= .11) and PO (0.2, IQR 0.08-0.42 and 0.18, IQR 0.09-0.46; p= .79). AUC of (TIMP-2) x (IGFBP7) were 0.6 (95%-CI 0.49-0.71) the first POD and 0.52 (95%-CI 0.41-0.62) PO. Higher median (TIMP-2)x(IGFBP7) occurred in pAKI KDIGO stage 3 at POD only (3.75, IQR 1.97-6.92; p= .003). Discussion In patients after AAR, assessment of (TIMP-2)x(IGFBP7) could not adequately predict pAKI. Further studies seem required.