Category: Epidemiology, Health Policy, Socioeconomics & Outcomes
Introduction & Objective : The optimal diagnostic test to obtain for patients presenting with suspected renal colic is controversial. Initial use of ultrasound (US), despite frequently requiring additional diagnostic imaging, carries a lower average cost and radiation dose compared to use of standard dose CT (SDCT) scan. Low dose CT (LDCT) scan is an alternative approach that combines high sensitivity for detection of nephrolithiasis with significantly lowered radiation dose. We present the first known study comparing the cost-effectiveness of these three management approaches, accounting for the potential downstream costs of radiation-induced secondary malignancy.
Methods : A PUBMED-based literature search was performed to identify model inputs, specifically, the rate at which additional diagnostic interventions are required for each approach, population characteristics of renal colic patients, the radiation dose associated with each study, and medical costs associated with radiation-induced malignancy. Estimates of radiation-induced malignancy rates were obtained from the BEIR VII Phase 2 report with dose extrapolation using the linear no-threshold model. The cost of imaging was obtained from the CMS Medicare fee schedule.
Results : No approach was demonstrated to have superior clinical outcomes to any other. Radiation doses of SDCT and LDCT were 14.1mSv and 1.54 mSv, respectively. Patients undergoing US and LDCT required subsequent SDCT in 33% and 13% of cases, respectively. Patients undergoing SDCT required subsequent US in 5% of cases. Use of LDCT after initial US could not be evaluated due to lack of available data. Average radiation dose was 3.4mSv for initial LDCT compared to 4.7mSv for initial US and 14.1mSv for initial SDCT. Risk of radiation-induced malignancy in this cohort was .0076%/mSv. Average cost of US was $115.56, while cost of CT scan was $203.85 regardless of dose. Cost of radiation-induced malignancy was estimated to be $81,441. Direct costs from medical imaging were lowest with US at $184.56 compared to $209.63 for SDCT and $230.35 for LDCT. When including costs of radiation-induced malignancy, US remained the least expensive at $214.21, compared to $251.27 for LDCT and $297.21 for SDCT. Becuase initial US followed by as needed SDCT carried a greater radiation dose than initial LDCT, at a threshold of $50,000/QALY, initial LDCT is cost effective over US if a case of radiation-induced malignancy carries a QALY loss of 6.92 years or greater.
Conclusions : This model suggests that initial US for evaluation of renal colic is the lowest cost option, while use of LDCT may be a reasonable alternative to minimize QALY lost due to downstream effects of ionizing radiation.
Todd Yecies– Resident , UPMC, UPMC, Pittsburgh, Pennsylvania
Jathin Bandari– Urology Fellow, University of Pittsburgh School of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
Michelle Semins– Endourology Faculty, UPMC, Pittsburgh, Pennsylvania
Anand Mohapatra– Resident Physician, Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania
Dr. Todd Yecies is a resident physician at UPMC. He is originally from the Bay Area in California. His research interests include assessment and management of the risks of ionizing radiation in urology and cost-effectiveness in the field of endourology.
University of Pittsburgh School of Medicine
University of Pittsburgh Medical Center
Clinical Instructor in Urology at the University of Pittsburgh Medical Center