AUA 2023: Cost-Effectiveness Analysis of Universal CT Staging Versus Selective CT Staging Strategies for Patients with cT1a Renal Masses

( The 2023 American Urological Association’s Annual Meeting included a session on Health Services Research: Value of Care, Cost & Outcomes Measures; this session featured a presentation by Dr. Diana Magee discussing the cost-effectiveness of CT scan of the chest versus chest x-ray (CXR) on patients with small renal masses.

The incidence of distant metastasis, including pulmonary metastases, is exceedingly rare in patients who have cT1a, or less than 4 cm, small renal masses. However, the use of chest staging is still prevalent within multiple guidelines. Further, these guidelines do not specify between CT chest versus CXR as a preferred modality. The economic ramifications of chest staging modality in cT1a renal masses is poorly understood. Dr. Magee and her co-authors conducted a cost-effectiveness study to explore this.

The authors developed a clinical decision tree to estimate detection rates of pulmonary metastases, as well as cost considerations, in two separate arms: a selective CT chest versus universal CT chest upon initial staging in a patient with a cT1a renal mass. Within the selective CT chest arm, patients first underwent a chest x-ray and only obtained a CT chest in the setting of an abnormal initial result. Model probabilities were obtained from the published literature, while direct costs were obtained from the Medicare procedure database. Primary outcomes included the proportion of true cancers detected, accuracy of the imaging modality, and incremental cost effectiveness ratio (CER).

According to Dr. Magee’s model, within the universal CT chest strategy, a larger proportion of true cancers were detected. However, when the imaging tests were assessed by accuracy, the selective staging arm was more accurate at 93.18% versus 76.74% in the universal staging arm. Further, the universal arm also noted a higher false positive rate of 23.21% as compared to 6.55% in the selective arm.

The authors calculated that a universal CT staging strategy would cost $59,931.13 to identify an additional metastasis that would be missed by a selective strategy.

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Dr. Magee concluded by noting that, although a universal staging method did find more true positives, this was along with an increase in the false positive rate. Given the low pretest probability of pulmonary metastases in patients with cT1a renal masses, chest x-ray with CT chest, if a positive result is obtained, may be a more cost-conscious strategy. 

Presented by: Diana Magee, MD, Fox Chase Cancer Center 

Written by: Ruchika Talwar, MD, Urologic Oncology Fellow, Vanderbilt University Medical Center, during the 2023 American Urological Association (AUA) Annual Meeting, Chicago, IL, April 27 – May 1, 2023