Renal resistive index as a predictive factor of delayed graft function: A meta-analysis.

BACKGROUND: Delayed graft function represents a major complication of kidney transplantation, leading to high rates of short and long-term morbidity. The aim of the present meta-analysis is to assess the role of renal resistive index measurement in the post-transplant period and evaluate its efficacy in the prediction of delayed graft function.

METHODS: Medline, Scopus, Cochrane Central Register of Controlled Trials CENTRAL, Clinicaltrials.gov and Google Scholar databases were systematically searched. Statistical analysis was performed with Review Manager 5.3, R 3.4.3 and Open Meta-Analyst software.

RESULTS: Fourteen studies were included with a total of 2741 kidney recipients. Patients with delayed graft function presented significantly higher rates of elevated renal resistive index (Odds Ratio: 1.96, 95% CI: [1.37, 2.81]). Also, renal resistive index values were significantly higher in patients with delayed graft function compared both to those with slow (Mean Difference: 0.04, 95% CI: [0.01, 0.07]) and immediate (Mean Difference: 0.10, 95% CI: [0.07, 0.12]) graft function. The pooled sensitivity for the detection of delayed graft function was estimated at 47.2% (95% CI: [30.9, 64.2]), the specificity at 69.3% (95% CI: [54.1, 81.2]) and the area under the curve at 0.613.

CONCLUSIONS: The present meta-analysis suggests the promising role of renal resistive index evaluation early after kidney transplantation, since its high values were significantly associated with higher incidence of delayed graft function. Future large-scale studies should define the most appropriate cut-off value and should incorporate renal resistive index in combined models in order to achieve optimal predictive accuracy.