DIAGNOSTIC EVALUATION OF THE ADRENAL INCIDENTALOMA - DECISION AND COST-EFFECTIVENESS ANALYSES

The goal of this study was to examine the clinical and economic outcom es of alternative diagnostic strategies for differentiating benign fro m malignant adrenal masses. Methods: We used cost-effectiveness assess ment derived from decision analysis and the economic perspective of th e payer of health care services, One-time evaluation with fine-needle aspiration (FNA) and combinations of chemical-shift MRI, noncontrast C T, I-131-6 beta-iodomethylnorcholesterol (NP-59) scintigraphy, with or without FNA, in a hypothetical cohort of 1000 patients with incidenta lly discovered unilateral, nonhypersecretory adrenal masses. We calcul ated and compared the diagnostic effectiveness, costs and cost-effecti veness of the alternative strategies based on estimates from published literature and institutional charge data. Results: At an assumed base line malignancy rate of 0.25, diagnostic utility varied from 0.31 (CT0 ) to 0.965 (NP-59) and diagnostic accuracy from 0.655 [noncontrast CT using a cut-off attenuation value of greater than or equal to 0 (CT0)] to 0.983 (NP-59). The average cost per patient per strategy ranged fr om $746 (NP-59) to $1745 (MRI +/- FNA). The best and worst potential c ost-to-diagnostic utility ratios were 773 (NP-59) and 2839 (CT0) and 7 59 (NP-59) and 1982 (MRI +/- FNA) for cost and diagnostic accuracy, re spectively. The NP-59 strategy was the optimal choice regardless of th e expected outcome examined: cost, diagnostic utility, diagnostic accu racy or cost-effectiveness. Varying the prevalence of malignancy did n ot alter the cost-effectiveness advantage of NP-59 over the other diag nostic modalities, Conclusion: Based on available estimates of reimbur sement costs and diagnostic test performance and using reasonable clin ical assumptions, our results indicate that the NP-59 strategy is the most cost-effective diagnostic tool for evaluating adrenal incidentalo mas over a wide range of malignancy rates and that additional clinical studies are warranted to confirm this cost-effectiveness advantage.