The correlation of intraoperative oliguria with acute kidney injury after noncardiac surgery: a systematic review and meta-analysis

Acute kidney injury (AKI) occurs commonly after major surgery and is correlated with increased in-hospital morbidity and mortality. There is no consensus on whether intraoperative oliguria affects postoperative AKI. We conducted a meta-analysis to systematically assess the correlation of intraoperative oliguria with postoperative AKI. METHODS: PubMed, Embase, Web of Science, and Cochrane Library databases were searched to identify reports on the relationship between intraoperative oliguria and postoperative AKI. Quality was assessed using the Newcastle–Ottawa Scale. The primary outcomes were the unadjusted and multivariate-adjusted odds ratios (ORs) for intraoperative oliguria to correlate with postoperative AKI. The secondary outcomes included intraoperative urine output in the AKI and non-AKI groups, the demand for postoperative renal replacement therapy (RRT), in-hospital mortality, and length of hospital stay in the oliguria and non-oliguria groups. RESULTS: Nine eligible studies with 18 473 patients were included. The meta-analysis revealed that patients with intraoperative oliguria had a considerably greater risk of postoperative AKI (unadjusted OR: 2.03, 95% CI: 1.60–2.58, I (2)=63%, P<0.00001; multivariate-adjusted OR: 2.00, 95% CI: 1.64–2.44, I (2)=40%, P<0.00001). Further subgroup analysis did not find differences between different oliguria criteria or surgical types. Furthermore, the AKI group’s pooled intraoperative urine output was less (mean differences: −0.16, 95% CI: −0.26 to −0.07, P<0.001). Intraoperative oliguria was associated with increased demand for postoperative RRT (risk ratios: 4.71, 95% CI: 2.83–7.84, P<0.001) and in-hospital mortality (risk ratios: 1.83, 95% CI: 1.24–2.69, P=0.002), but not with prolonged length of hospital stay (mean differences: 0.55, 95% CI: −0.27 to 1.38, P=0.19). CONCLUSIONS: Intraoperative oliguria was significantly associated with a higher incidence of postoperative AKI, as well as increased in-hospital mortality and demand for postoperative RRT, but not with prolonged hospitalization.