Association of Oliguria With Acute Kidney Injury Diagnosis, Severity Assessment, and Mortality Among Patients With Critical Illness

Abstract

IMPORTANCEThe current definition and staging of acute kidney injury (AKI) considers alterations in serum creatinine (sCr) level and urinary output (UO). However, the relevance of oliguria-based criteria is disputed. OBJECTIVETo determine the contribution of oliguria, as defined by the Kidney Disease: Improving Global Outcomes (KDIGO) criteria, to AKI diagnosis, severity assessment, and short-and longterm outcomes. DESIGN, SETTING, AND PARTICIPANTS This cohort study included adult patients admitted to a multidisciplinary intensive care unit from January 1, 2010, to June 15, 2020. Patients receiving longterm dialysis and those who declined consent were excluded. Daily sCr level and hourly UO measurements along with sociodemographic characteristics and severity scores were extracted from electronic medical records. Long-term mortality was assessed by cross-referencing the database with the Swiss national death registry. The onset and severity of AKI according to the KDIGO classification was determined using UO and sCr criteria separately, and their agreement was assessed. MAIN OUTCOMES AND MEASURES Using a multivariable model accounting for baseline characteristics, severity scores, and sCr stages, the association of UO criteria with 90-day mortality was evaluated. Sensitivity analyses were conducted to assess how missing sCr, body weight, and UO values, as well as different sCr baseline definitions and imputations methods, would affect the main results. RESULTS Among the 15 620 patients included in the study (10 330 men [66.1%] with a median age of 65 [IQR, 53-75] years, a median Simplified Acute Physiology Score II score of 40.0 [IQR, 30.0-53.0], and a median follow-up of 67.0 [IQR, 34.0-100.0] months), 12 143 (77.7%) fulfilled AKI criteria.Serum creatinine and UO criteria had poor agreement on AKI diagnosis and staging (Cohen weighted κ, 0.36; 95% CI, 0.35-0.37; P < .001). Compared with the isolated use of sCr criteria, consideration of UO criteria enabled identification of AKI in 5630 patients (36.0%). Those patients had a higher 90-day mortality than patients without AKI (724 of 5608 [12.9%] vs 288 of 3462 [8.3%]; P < .001).On multivariable analysis accounting for sCr stage, comorbidities, and illness severity, UO stages 2 and 3 were associated with a higher 90-day mortality (odds ratios, 2.4 [95% CI, 1.6-3.8; P < .001] and 6.2 [95% CI, 3.7-10.5; P < .001], respectively). These results remained significant in all sensitivity analyses. CONCLUSIONS AND RELEVANCEThe findings of this cohort study suggest that oliguria lasting more than 12 hours (KDIGO stage 2 or 3) has major AKI diagnostic implications and is associated with outcomes irrespective of sCr elevations.

Sequential Nephron Blockade In Acute Kidney Injury In Critically Ill Patients.

“…Mortality in non-responders was nearly thrice (41.9% vs. 14.8%) as that of responders. The high mortality among non-responders in our study is consistent with other reports [23,34]. In our study, SOFA score > 9, negative diuretic response, need for RRT and a higher positive uid balance were independently associated with mortality.…”

“…AKIN-criteria has shown similar effectiveness in predicting in-hospital mortality as KDIGO [33]. Oliguria-based criteria improve patients' risk estimation and clinicians' ability to evaluate AKI [34]. Patients with age less than 18 years, chronic kidney disease and those with unstable hemodynamics de ned as vasoactive ionotropic score more than 25 [35] were excluded.…”

Sequential nephron blockade in acute kidney injury in critically ill patients.

“…KDIGO-criteria has shown good effectiveness in predicting in-hospital mortality [33]. Oliguria-based criteria improve patients' risk estimation and clinicians' ability to evaluate AKI [34].…”

Emerging early diagnostic methods for acute kidney injury

“…In addition, only persistent oliguria is an effective signal of acute kidney injury. In this case, UO cannot diagnose AKI in time 16 . Moreover, the changes of SCR and UO have a long-time delay compared with the important structural changes of the kidney of AKI.…”