Thyroid nodules classified as atypia of undetermined significance have a significant risk of malignancy and can be managed by surveillance or diagnostic surgery. There are currently no publications evaluating surveillance compliance.
To determine whether thyroid nodule surveillance compliance is influenced by patient demographics or plan type, and whether patient or nodule characteristics influence triage to surgery.
Design: Retrospective case series from 2010-2018.
Setting: United States Military Health System.
Participants: 481 patients with a thyroid nodule fine-needle aspiration classified as atypia of undetermined significance for whom treatment and follow-up information was available.
Main Outcomes and Measures: Compliance with nodule surveillance and the influence of patient demographics, sonographic nodule characteristics and surveillance plan on compliance or triage to surgery.
Results: A total of 289 nodules were surveilled and 192 diagnostic lobectomies were performed. An initial surveillance plan was documented in 93% (268/289) and 86% (231/268) complied. The most common plans were repeat biopsy in 78% (210/268) or ultrasound in 20% (53/268). A second plan was documented in 88% (204/231) of those who complied. The most common plans were ultrasound in 87% (178/204) or repeat biopsy in 8% (17/204). Compliance with the second plan was 64% (130/204), significantly lower than with the first (OR 3.6, 95% CI: [2.3, 5.6], P < 0.0001). Only 45% (130/289) were surveilled twice. Age and gender did not significantly affect compliance rates. Compliance with primary care ultrasound surveillance was 40% (21/52), significantly lower than with a specialist (77% [137/179]; OR 4.8, 95% CI: [2.5, 9.3, P < 0.0001). In the surgical cohort, age was lower (47 vs 52, P = 0.0002), nodule size was greater (2.6 vs 2.0 cm, P < 0.0001), and internal vascularity was more common (80% vs 66%, P = 0.003). The risk of malignancy after diagnostic lobectomy was 38% (73/192).
Conclusions and Relevance: Compliance with surveillance of thyroid nodules classified as atypia of undetermined significance was poor in this military cohort. Ultrasound surveillance by a specialist may be more reliable than with primary care. Age, nodule size, and internal vascularity may have influenced providers towards recommending diagnostic lobectomy.