Renal Resistive Index Better Predicts the Occurrence of Acute Kidney Injury Than Cystatin C

Abstract

The objective of this study was to determine the predictive value of the renal resistive index (RI) and cystatin C values in serum (SCys) and urine (UCys) in the development of acute kidney injury (AKI) in critically ill patients with severe sepsis or polytrauma. This was a prospective, double-center, descriptive study. There were 58 patients with severe sepsis (n= 28) or polytrauma (n = 30). Renal resistive index, SCys, and UCys were measured within 12 h following admission (day 1 [D1]) to the intensive care unit. Renal function was assessed using the AKI network classification: On day 3 (D3), 40 patients were at stage 0 or 1, and 18 were at stage 2 or 3. Patients with AKI stage 2 or 3 had significantly higher RI (0.80 vs. 0.66, P < 0.0001), SCys (1.23 vs. 0.68 mg/L, P = 0.0002), and UCys (3.32 vs. 0.09 mg/L, P = 0.0008). They also had higher Simplified Acute Physiology Score II, arterial lactate level, and intensive care unit mortality. In multivariate analysis, an RI of greater than 0.707 on D1 was the only parameter predictive of the development of AKI stage 2 or 3 on D3 (P = 0.0004). In the subgroup of patients with AKI stage 2 or 3 on D1, RI remained the only parameter associated with persistent AKI on D3 (P = 0.016). In multivariate analysis comparing the predictive value of RI, SCys, and UCys, RI was the only parameter predictive of AKI stage 2 or 3 on D3. Renal resistive index seems to be a promising tool to assess the risk of AKI.

Acute kidney disease and renal recovery: consensus report of the Acute Disease Quality Initiative (ADQI) 16 Workgroup

“…However, clinical risk scores for persistent AKI have not been validated for general use and the risk factors that contribute to persistent AKI, AKD, and delayed recovery among hospitalized patients are not known. Several studies have identified clinical risk scores, biomarkers, imaging, and functional tests to differentiate rapid reversal of AKI from persisting AKI [19][20][21][22][23][24][25][26][27] (see Supplementary information S2 (table)). In the opinion of the ADQI workgroup, these tools would likely work well together and are a recommended area of future research…”

Renal Relevant Radiology

“…Studies suggest that RI may be a useful tool for predicting AKI, distinguishing ATN (or other parenchymal diseases) from prerenal azotemia, and predicting severity in AKI as summarized in Table 3. Three studies (26)(27)(28) have examined the utility of RI to predict AKI; in these studies, RIs of 0.74, 0.74, and 0.71 were found to be useful cut-points to predict AKI 1-5 days after the RI measurement in patients after cardiac bypass requiring surgery, with septic shock, or in the intensive care unit (ICU) for trauma or sepsis, respectively; patients who did not develop AKI had initial RIs of 0.68, 0.68, and 0.66, respectively. In studies of RI in prerenal azotemia versus intrinsic AKI (29)(30)(31), an RI$0.75 correlated well with the diagnosis of ATN, while prerenal azotemia was typically associated with an RI,0.71.…”

Acute kidney injury in the perioperative period and in intensive care units (excluding renal replacement therapies)

“…Several other preliminary trials also suggest that the resistive index would allow clinicians to distinguish pre-renal (non-organic) from intrarenal (organic) AKI [45][46][47], to predict renal function outcome at days 3 or 5 [43,[48][49][50] and to predict RRT [51]. Thus, these studies suggest that the resistive index could be a tool for assessing renal prognosis with a good sensitivity and specificity [45,[47][48][49][50][51]. Certain studies performed on non-critically ill septic patients (35-91) have small sample sizes, which are mostly monocentric in nature or have poor methodological design [45-47, 49, 50].…”