Does the Use of Ultrafiltration Increase the Risk of Post-Operative Acute Kidney Injury? A Multi-Center Analysis

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1 Does the Use of Ultrafiltration Increase the Risk of Post-Operative Acute Kidney Injury? A Multi-Center Analysis Gordon R. DeFoe, CCP, John Pieroni, CCP, Craig S. Warren, CCP, Charles F. Krumholz, CCP, Robert C. Groom, CCP, MS for the Northern New England Cardiovascular Disease Study Group

2 Disclosure Authors have no disclosures

3 Northern New England Cardiovascular Disease Study Group University of Vermont Medical Center Dartmouth- Hitchcock Medical Center Catholic Medical Center Parkland Medical Center affiliated with CMC Eastern Maine Medical Center Central Maine Medical Center Maine Medical Center Concord Hospital Parkland Medical Center The Northern New England Cardiovascular Disease Study Group exists to develop and exchange information concerning the treatment of cardiovascular disease. It is a regional, voluntary, multi-disciplinary group of clinicians, hospital administrators, and health care research personnel who seek to improve continuously the quality, safety, effectiveness, and cost of medical interventions in cardiovascular disease.

4 Methods Data: 24,955 patients having CABG, valve and CABG/valve procedures on CPB from Exclusions: Abnormal pre-op creatinine (>1.3 for men; >1.1 for women) or dialysis (N=4,572) Patients with CHF (N=4,277) Patients who received >3 liters of fluid intraoperative (N=1,980) Analysis dataset: 14,126 patients with 1799 receiving UF

5 Methods Analysis: propensity matched on age, gender, BSA, pre-op hematocrit, co-morbid disease, type of procedure and hospital to UF patients, resulting in 1,686 matched pairs. Outcome: Acute Kidney Injury using AKIN definition (increase in serum creatinine level of >=0.3 mg/dl or >=50% increase in serum creatinine or new requirement for dialysis).

6 Patient Characteristics Variable No ultrafiltration Ultrafiltration p value* Number of procedures 12,327 1, Age in years, % by group < < >= Sex, % female <0.001 Body surface area, % yes < < >= Pre-op HCT, % yes < < >= Preop WBC >12,000, % yes

7 Patient and Disease Characteristics Variable No ultrafiltration Ultrafiltration p value* Prior CABG, % yes Prior PCI, % yes <0.001 Comorbid disease, % yes Vascular disease Diabetes COPD Ejection fraction, % < >= Coronary artery disease, % yes Left main stenosis >=50% <0.001 Three vessel disease <0.001 MI within 7 days Priority at surgery, % Elective <0.001 Urgent Emergency

8 Patient and Disease Characteristics Variable No ultrafiltration Ultrafiltration p value* Procedure, % CABG <0.001 Valve CABG+valve Year, % < Hospital, % DHMC <0.001 UVMMC MMC CMC EMMC CH CMMC Predicted RF/insuff (AKIN), median %

9 Variable Propensity Matched No ultrafiltration Ultrafiltration p value* Number of procedures 1,686 1, Age in years, % by group < NS >= Sex, % female NS Body surface area, % yes < NS >= Pre-op HCT, % yes < NS >= Preop WBC >12,000, % yes NS

10 Propensity Matched Variable No ultrafiltration Ultrafiltration p value* Prior CABG, % yes NS Prior PCI, % yes NS Comorbid disease, % yes Vascular disease NS Diabetes NS COPD NS Ejection fraction, % < >= Coronary artery disease, % yes Left main stenosis >=50% NS Three vessel disease NS MI within 7 days NS Priority at surgery, % Elective NS Urgent Emergency

11 Propensity Matched Variable No ultrafiltration Ultrafiltration p value* Procedure CABG NS Valve CABG+valve Hospital, % DHMC NS UVMMC MMC CMC EMMC CH CMMC Predicted RF/insuff (AKIN), median % NS

12 Perioperative and In-Hospital Outcomes No ultrafiltration Ultrafiltration p value* Number of procedures 1,686 1, Nadir HCT on CPB, median % <0.001 Last HCT on CPB, median % <0.001 Intraop RBCs (only), % yes <0.001 Postop RBCs (only), % yes Intra- and/or postop RBCs, % yes <0.001 Acute kidney injury, % yes Cases with abnormal preop Cr, CHF or >3L intraop fluid excluded * p value for chi square test or Wilcoxon rank sum test

13 *NOTE: Missing hctpre imputed The Northern New England Cardiovascular Disease Study Group AKI by AKI UF, by Pre-op UF use within Hematocrit HCT/blood and groups RBCs p chisq= p chisq= p chisq= p chisq= No UF UF No UF UF No UF UF No UF UF hctpre>=40, no RBCs hctpre<40, no RBCs hctpre>=40, RBCs hctpre<40, RBCs

14 Results-Adjusted Variable Adjusted O.R. 95% CI Ultrafiltration Preop HCT >=43 (ref.) -- Preop HCT Preop HCT Preop HCT < RBCs intra/postop

15 Limitations Unmeasured confounding No data that controls for renal perfusion

16 Conclusions Rate of AKI was higher in a propensity-matched data set of UF versus non-uf patients. The addition of transfusion and low pre-operative hematocrit to the model indicates that transfusion and anemia are stronger predictors of AKI than is UF. The use of UF in a subset of patients with a baseline hematocrit >=40 and no transfusion showed no difference in AKI rate.