Cost-effective initial assessment strategies for thyroid nodules in iodine-adequate areas

In the initial assessment of thyroid nodules, thyrotropin (TSH) has very low sensitivity for assessing functional thyroid nodules (FTNs). The false negativity in FTNs and the false positivity in non-FTNs misinterpreted by TSH will raise unnecessary assessment costs. Therefore, the aim of this study is to explore the values of the TSH and color flow Doppler sonography (CFDS) combined strategies in reducing the unnecessary assessment costs.

2383 patients with thyroid nodules were retrospectively analyzed, including 107 FTNs and 2276 non-FTNs. Four strategies including TSH, CFDS, Combination 1 (TSH+/CFDS+, TSH+/CFDS-, and TSH-/CFDS+ defined as positive; TSH-/CFDS- defined as negative) and Combination 2 (TSH+/CFDS+ defined as positive; TSH+/CFDS-, TSH-/CFDS+, and TSH-/CFDS- defined as negative) were separately used for initial assessment. The four strategies were compared using the testing cost ratio of fine-needle aspiration (FNA) to thyroid scintigraphy (TS) (marked as C_FNA/TS) as main outcome measure.

Compared with TSH, Combination 1 prevented 15.89 % of FTNs from unnecessary FNA, but increased the number of non-FTNs subjected to unnecessary ^99mTc-TS by 9.31 %. Combination 2 prevented 5.32 % of non-FTNs from unnecessary TS, but increased the number of FTNs subjected to unnecessary FNA by 18.69 %. When C_FNA/TS was <6.05, the lowest total cost was found in Combination 2. The TSH and Combination 1 were optimal at 6.05 ≤ C_FNA/TS ≤ 12.47 and C_FNA/TS > 12.47, respectively.

The combined strategies can be used to supplement TSH in the initial assessment of thyroid nodules in iodine-adequate areas, depending on the testing costs of FNA and TS.