Utility of Patient-Reported Risk Factors for Identifying Advanced Chronic Kidney Disease Before Outpatient CT: Comparison With Recent ACR/NKF Consensus Criteria.

BACKGROUND. Practices vary for screening patients for risk of renal dysfunction before administration of iodinated contrast medium. A 2020 American College of Radiology/National Kidney Foundation (ACR/NKF) consensus statement provided streamlined screening criteria. OBJECTIVE. The purpose of this study was to assess the yield of patient-reported risk factors for identifying estimated glomerular filtration rate (eGFR) less than 30 mL/min/1.73 m2 before outpatient CT. METHODS. This retrospective study was performed at a health system that implemented an electronic screening form for patients to complete before outpatient CT encounters to report undergoing dialysis, taking cancer-treating medications, having kidney disease, undergoing prior kidney surgery, having diabetes mellitus treated with medication, having hypertension treated with medication, or having multiple myeloma. Patients with any risk factor were required to undergo eGFR testing before CT. Of 44,708 patients completing the form from June 1, 2020, through February 28, 2021, 10,256 patients (5315 men, 4941 women; mean age, 66.8 ± 11.9 [SD] years; range, 21-98 years) underwent eGFR testing on the day of CT. Multivariable regression analysis for predicting reduced eGFR was performed. Findings were compared with those from theoretic use of the ACR/NKF criteria. RESULTS. Same-day testing yielded eGFR less than 30 mL/min/1.73 m2 in 1.4% (144/10,256) of patients. The only significant independent predictors of low eGFR were dialysis (odds ratio [OR], 203.30], kidney disease (OR, 12.55), and diabetes mellitus treated with medication (OR, 2.44). If the ACR/NKF criteria (only kidney disease, defined as dialysis, kidney disease, or prior kidney surgery) had been followed as a trigger for eGFR testing, the number of patients needing testing would have decreased 89.7%, from 10,256 to 1059; yield would have increased to 7.2% (76/1059); and 47.2% (68/144) of patients with low eGFR would have been missed. If the ACR/NKF criteria had been followed but diabetes mellitus been considered a required rather than an optional criterion, the number of patients needing testing would have decreased 77.1%, to 2353; yield would have increased to 4.0% (95/2353); and 34.0% (49/144) of patients with low eGFR would have been missed. CONCLUSION. Using patient-reported risk factors resulted in frequent eGFR testing but low yield of low eGFR. Commonly applied risk factors were not independently associated with low eGFR. CLINICAL IMPACT. Application of ACR/NKF criteria would substantially reduce eGFR testing, but patients with renal dysfunction would be missed. The statement should consider omitting kidney surgery as a trigger for eGFR testing and including diabetes mellitus as a required trigger.