ACS 2019: The Harms of Hematuria Workup: Modeling the Risk-Benefit of Using Split-Bolus CT Urography to Reduce Radiation Exposure in a Theoretical Cohort

San Francisco, California ( Jeremiah Dallmer discussed how CT urography (CTU) is used to evaluate patients with gross (GH) or microscopic hematuria (MH). CTU is a high radiation dose scan and thus confers a higher risk of secondary malignancy. A CTU “Split-Bolus” (SB) protocol reduces radiation exposure; however, it may reduce sensitivity.   This study uses a theoretical cohort of patients with hematuria to model the risk of missing malignancies against the benefit of averting secondary malignancies.

The prevalence of renal cell carcinoma (RCC) and upper tract urothelial carcinoma (UTUC) in hematuria patients was calculated by a pooled analysis of cohort studies, which, in conjunction with SB sensitivity, allows the estimation of missed malignancies. The number of secondary malignancies prevented was calculated from lifetime attributable risk estimates. Sensitivity analyses were run to determine the minimum sensitivity required for net population benefit.

Estimates of SB-CTU sensitivity ranged from 80-100% (mean 95.2%). At the very low estimate of 80% sensitivity, SB-CTU was beneficial for men <50yr and women <60yr in patients with AMH. A 10% increase in sensitivity improved the benefit of one decade for both sexes, covering 68.8% of hematuria patients. The overall population of MH patients benefited from SB-CTU at 91.1% sensitivity (Fig 1). However, for GH patients the threshold for overall population benefit was very high at 98.4% sensitivity.

In summary, this study showed that SB-CTU can safely reduce the radiation dose for 70% of the population of patients with MH, but these data suggest this is not currently advisable for GH or other high-risk patients.

Presented by: Jeremiah R. Dallmer, Vanderbilt University Medical Center, Nashville, Tennessee

Written by: Stephen B. Williams, MD, Medical Director for High Value Care; Chief of Urology, Associate Professor, Director of Urologic Oncology, Director Urologic Research, The University of Texas Medical Branch at Galveston, TX at the 2019 American College of Surgeons Clinical Congress October 27-31, 2019  - San Francisco, CA