Increased workload without clinical benefit: Results following implementation of the ACR-TIRADS system for thyroid nodules.

OBJECTIVE

The ACR-TIRADS system for stratifying thyroid nodule malignancy risk has been widely promoted and implemented. We audited its introduction at a large public hospital in Auckland, New Zealand.

DESIGN

Audit of outcomes following thyroid nodule fine needle aspiration (FNA) before/after ACR-TIRADS.

PATIENTS

Individuals undergoing thyroid FNA 2017-2019.

MEASUREMENTS

From medical records, we obtained details from the pre-FNA ultrasound (nodule size, TIRADS points/levels, radiologist recommendation for FNA), Bethesda (B) cytology classification, histology and post-FNA follow-up.

RESULTS

Four hundred and twenty-two individuals had 564 FNAs, 163 had surgery and 54 (13%) had cancer in the primary nodule. 37/54 (69%) cancers were papillary thyroid carcinoma (median size 25 mm, 87% ≥10 mm, 61% ≥20 mm). Following ACR-TIRADS introduction, FNA recommendations increased greater than twofold, FNAs performed by 71%-83%, and the monthly rate of FNAs and operations by 60% and 40%, respectively. However, the proportion of cancers/FNA remained similar (9.9% post-TIRADS vs. 8.7% pre-TIRADS). The proportions of FNA results remained stable for B2-B4 categories, but doubled (11% vs. 5%) for B5-B6: 15 FNAs were needed to identify an additional B5/B6 lesion. TIRADS-5 nodules had a higher proportion of B5/B6 (20%) and a lower proportion of B2 (30%) than TIRADS-3 (2%, 57%, respectively) and TIRADS-4 (9%, 56%) nodules. About 5 additional cancers/year were diagnosed, but they were more often small (49% vs. 8% <2 cm, 17% vs. 0% <1 cm).

CONCLUSION

ACR-TIRADS introduction increased workload (FNAs and operations), without increasing the proportion of cancers/FNA. It led to a few more cancers being diagnosed, but many were small and of uncertain clinical significance.