KDIGO Defined AKI: The Urine Output Criteria Have Feelings Too AKI & CRRT 2018, March 8, 2018 Scott Sutherland Stanford Children s Health
Overview Review the data behind the UOP criteria Highlight how the use of the UOP criteria changes AKI prevalence Highlight the outcomes associated with meeting the UOP criteria Stage 1 Stage 2 Stage 3 KDIGO Urine Output Criteria < 0.5mL/kg/hr for 6-12 hrs < 0.5mL/kg/hr for 12-24 hrs < 0.3mL/kg/hr for > 24hrs OR anuria for 12hrs
KDIGO: Food For Thought The thresholds for urine flow for the definition of AKI have been derived empirically and are less well substantiated than the thresholds for increase in SCr. The use of urine output criteria for diagnosis and staging has been less well validated and in individual patients the need for clinical judgment regarding the effects of drugs, fluid balance, and other factors must be included.
KDIGO: Food For Thought The influence of urinary output criteria on AKI staging needs to be further investigated. Influence of fluid balance, percent volume overload, diuretic use, and differing weights (actual, ideal body weight, lean body mass) should be considered. Also, it is currently not known how urine volume criteria should be applied (e.g., average vs. persistent reduction for the period specified).
UOP vs. Creatinine: Incidence KDIGO Defined AKI AKI by Cr and UOP Criteria 26% 74% AKI No AKI 50% 12% 38% Cr only UOP only Cr and UOP n = 32,045 n = 23,866 62% of AKI patients met creatinine criteria 88% of AKI patients met UOP criteria 38% of patients with AKI would be missed if only the creatinine criteria were applied Kellum JA, et al.. Classifying AKI by Urine Output versus Serum Creatinine Level. J Am Soc Nephrol. 2015 Sep;26(9):2231-8
UOP vs. Creatinine: Mortality 60% 50% 40% Cr only UOP only Cr and UOP 51% 30% 20% 10% 8% 5% 11% 22% 11% 12% 8% 18% 0% Stage 1 Stage 2 Stage 3 All AKI mortality greater than no AKI (4.3%) UOP and Creatinine have similar mortality in isolation Meeting both criteria = significantly greater mortality Kellum JA, et al.. Classifying AKI by Urine Output versus Serum Creatinine Level. J Am Soc Nephrol. 2015 Sep;26(9):2231-8
UOP vs. Creatinine: Mortality Plus Similar patter for other outcomes Cr UOP Both RRT 4.9% 2.1% 25% LOS (days) 14 13 22 Long term only the patients who met Stage 3 by both criteria were at significantly increased risk for ESRD Kellum JA, et al.. Classifying AKI by Urine Output versus Serum Creatinine Level. J Am Soc Nephrol. 2015 Sep;26(9):2231-8
UOP vs. Creatinine: Stage Agreement Entire cohort (AKI and non-aki) Creatinine and UOP agree 41% Creatinine and UOP disagree 59% AKI Cohort Creatinine and UOP agree 21% Creatinine and UOP disagree 79% Creatinine and UOP disagree by 2+ stages Entire cohort 25% AKI Cohort 34% Kellum JA, et al.. Classifying AKI by Urine Output versus Serum Creatinine Level. J Am Soc Nephrol. 2015 Sep;26(9):2231-8
UOP vs. Creatinine: Incidence KDIGO Defined Severe (Stage 2/3) AKI Severe (Stage 2/3) AKI by Cr and UOP Criteria 85% 15% Severe AKI No Severe AKI 18% 13% 69% Cr only UOP only Cr and UOP n n = = 32,045 3,318 n = n 23,866 = 496 82% of Severe AKI patients met creatinine criteria 31% of Severe AKI patients met UOP criteria 18% of patients with Severe AKI would be missed if only the creatinine criteria were applied AWARE Analysis 2018
UOP vs. Creatinine: Mortality Mortality (%) 40% 35% 30% 25% 20% 15% 10% 5% 0% 35% 7% 8% 3% No Severe AKI Cr only UOP only Cr and UOP All Severe AKI mortality greater than no AKI UOP and Creatinine have similar mortality in isolation Meeting both criteria = significantly greater mortality AWARE Analysis 2018
UOP vs. Creatinine: Mortality Plus Similar patter for other outcomes Cr UOP Both RRT 3% 10% 59% ICU LOS (days) 5 4 7 AWARE Analysis 2018
Summary Clearly the UOP criteria are important Identify AKI missed by creatinine criteria Patient identified by UOP criteria have outcomes similar to those identified by creatinine UOP and creatinine criteria are not equivalent Disagree on AKI vs. no AKI Disagree on AKI stage (sometimes significantly) Outcome impact is independent and seemingly additive or exponential
Summary AKI criteria don t diagnose injury, they diagnose dysfunction Excretory dysfunction (serum creatinine) Fluid homeostasis dysfunction (oliguria) More types of dysfunction = poorer outcomes For now, presence of multiple types of dysfunction indicative of greater injury When true markers of injury available, creatinine and UOP could be considered AKI severity parameters or modifiers