Cost-Effectiveness of Follow-Up Imaging for Incidental Adrenal Nodules to Rule Out Adrenocortical Carcinoma

Several follow-up recommendations have been developed to assess the risk for malignancy of incidental adrenal nodules, but none has been validated in prospective trials. The purpose of this study was to develop a simulation model that evaluates the cost-effectiveness of follow-up imaging to detect adrenocortical carcinoma in adrenal nodules in patients with no known malignancy.

Using 1 million simulated adult patients with incidental adrenal nodules measuring 1 to 4 cm detected on contrast-enhanced CT, follow-up strategies were evaluated, including ACR and American Urological Association recommendations. Variants of the ACR recommendations using noncontrast CT only, or noncontrast MRI only, instead of washout CT were also evaluated. Costs and life years (LYs) were calculated for the simulated cohort. A probabilistic sensitivity analysis was performed by varying model parameters.

In the base-case analysis, the only cost-effective strategy under a willingness-to-pay threshold of $100,000 per LY was the variant ACR recommendation using noncontrast CT only at the time of diagnosis ($241 per patient). The standard ACR recommendation with washout CT resulted in fewer LYs at increased cost. The probabilistic sensitivity analysis demonstrated that at the $100,000 per LY threshold, the variant ACR recommendation with noncontrast CT was cost effective in 50% of simulations, the American Urological Association recommendations (washout-disregarded variant) were cost effective in 20%, the variant ACR recommendation with MRI was cost effective in 16%, and no follow-up was cost effective in 10%.

Follow-up imaging with noncontrast CT for incidental adrenal nodules appears to be cost effective to rule out adrenocortical carcinoma. However, strategies using washout CT are not cost effective.