Cost-Effectiveness of FDG-PET/CT for Cytologically Indeterminate Thyroid Nodules: a Decision Analytic Approach

D. Vriens, E. Adang, R. Netea-Maier, J. Smit, J. de Wilt, W. Oyen and L. de Geus-Oei

dept. of Radiology and Nuclear Medicine.
May, 2014



Context: Patients with thyroid nodules of indeterminate cytology undergo diagnostic surgery according to current guidelines. In 75\% of patients, the nodule is benign. In these patients, surgery was unnecessary and unbeneficial as complications may occur. Preoperative FDG-PET/CT was found to have a very high negative predictive value (96\%) and might therefore avoid futile surgery, complications and costs. In the USA, two molecular tests of cytology material are routinely used for this purpose. Objective: 5-year cost-effectiveness for routine implementation of FDG-PET/CT was evaluated in adult patients with indeterminate fine-needle aspiration cytology and compared with surgery in all patients and both molecular tests. Design: A Markov decision model was developed to synthesize the evidence on cost-effectiveness about the four alternative strategies. The model was probabilistically analysed. One-way sensitivity analyses of deterministic input variables likely to influence outcome were performed. Setting and Subjects: The model was representative for adult patients with cytologically indeterminate thyroid nodules. Main Outcome Measures: The discounted incremental Net Monetary Benefit (iNMB), the efficiency decision rule containing outcomes as quality adjusted life years (QALY) and (direct) medical cost, of implementation of FDG-PET/CT is displayed. Results: Full implementation of FDG-PET/CT resulted in 40\% surgery for benign nodules, compared to 75\% in the conventional approach, without a difference in recurrence free and overall survival. The FDG-PET/CT modality is the more efficient technology, with a mean iNMB of € 3,684 compared to surgery in all. Also, compared to a gene expression classifier test and a molecular marker panel, the mean iNMB of FDG-PET/CT was € 1,030 and € 3,851, respectively and consequently the more efficient alternative. Conclusion: Full implementation of preoperative FDG-PET/CT in patients with indeterminate thyroid nodules could prevent up to 47\% of current unnecessary surgery leading to lower costs and modest increase of health-related quality of life. Compared to an approach with diagnostic surgery in all patients and both molecular tests, it is the least expensive alternative with similar effectiveness as the gene-expression classifier.