Exploring the atypia of undetermined significance: Malignant ratio, ThyroSeq v3 positive call rate, molecular-derived risk of malignancy, and risk of malignancy as possible quality metric tools in thyroid cytology

Background

The atypia of undetermined significance (AUS) category is heterogeneous, leading to variations in its use. To prevent excessive usage, the AUS rate should be ≤10%. Although this recommendation aims to maintain diagnostic quality, it lacks supporting data. The AUS:Malignant (AUS:M) ratio has been proposed as a metric tool to evaluate AUS use. Furthermore, integrating ThyroSeq v3 (TSV3) positive call rate (PCR) and the molecular-derived risk of malignancy (MDROM) have been put forward as performance improvement tools. The authors reviewed their AUS:M ratios, TSV3 PCR, MDROM, and ROM.

Methods

Thyroid aspirates evaluated in the laboratory (from August 2022 to September 2023) by seven cytopathologists (CPs) were identified. AUS:M ratio, MDROM, ROM, and TSV3 PCR results for the laboratory and each CP were recorded and analyzed.

Results

A total of 2248 aspirates were identified (462 AUS and 80 malignant). The AUS:M ratio for the laboratory was 5.8 (CPs range, 2.8 to 7.3). The TSV3 PCR for the laboratory was 23% (CPs range, 11% to 41%). The MDROM for the laboratory was 19% (CPs range, 9% to 31%), whereas the ROM was 36% (CPs range, 29% to 50%). Linear regression analysis of AUS:M ratio versus TSV3 PCR and MDROM demonstrated a moderate positive correlation but a weak negative correlation to the ROM. Deviations from established targets were attributed to multiple factors.

Conclusion

The findings of this study underscore the importance of using a combination of metrics to evaluate diagnostic practices. By dissecting the practice patterns of each CP, the authors can measure different aspects of their performance and provide individualized feedback.