Missed diagnosis of acute kidney injury in older patients with invasive mechanical ventilation: a multicenter retrospective study

Objectives Patients who undergo mechanical ventilation (MV) are at higher risk of suffering from acute kidney injury (AKI). However, whether AKI is diagnosed in all patients and the association between AKI and mortality are unclear. Methods This was a retrospective, observational, multicenter cohort study conducted from January 2008 to December 2020 that included 3271 consecutive older patients (>= 75 years) who received invasive MV from four medical centers in Chinese PLA General Hospital. AKI was diagnosed according to the serum creatinine (Scr)-based Kidney Disease: Improving Global Outcomes guidelines by an absolute increase in Scr of >= 26.5 mu mol/L within the first 48 h of MV. The outcomes of patients with and without AKI and whether AKI was recognized were compared. Results A total of 1292 patients were included in the final evaluation. Three hundred seventy-six patients (29.1%) fulfilled the diagnostic criteria. Among the 376 AKI patients, the recognition rate and nonrecognition rate were 62.8% (236/376) and 37.2% (140/376), respectively. The overall 90-day mortality rate was 45.2% (584/1,292), which was dramatically increased in unrecognized AKI patients and recognized AKI compared to non-AKI patients (70.7% vs. 54.7% vs. 38.9%, respectively, P < 0.001). The survival of patients with recognized AKI was better than that of patients with unrecognized AKI. Multivariate logistic regression analysis revealed that recognized AKI was significantly associated with mean arterial pressure, positive end-expiratory pressure, uric acid, baseline Scr, and peak Scr. AKI was identified as an independent predictor of all-cause 90-day mortality (recognized AKI vs. non-AKI: HR = 1.722; 95% CI = 1.399-2.119; P < 0.001 and unrecognized AKI vs. non-AKI: HR = 2.632; 95% CI = 2.081-3.329; P < 0.001). Conclusions AKI is a common complication in older patients undergoing MV, with substantial underdiagnosis and undertreatment. Interventions for improving the diagnosis of AKI are urgently needed.