Low Detection Rates for Most Indications
The retrospective observational cohort study included 1739 adults (76% women; mean age, 53 years) who underwent dedicated thyroid ultrasounds between 2017 and 2019. In most cases, the recommendation for biopsy was determined using the American College of Radiology TI-RADS system, based on nodule size and TI-RADS category.
The most common indication for thyroid ultrasound, suspected palpable nodule, accounted for 40% of those performed. Follow-up for an “incidentaloma” was the indication in 28% of patients, and referral for compressive and metabolic symptoms accounted for 13% and 6% of ultrasounds, respectively.
Among all ultrasounds performed, 62% identified a thyroid nodule. Patients referred for incidental findings had the highest percentage of ultrasounds with thyroid nodules present at 94%. By contrast, in those referred for suspected palpable nodule on exam and for compressive symptoms, nodules were identified on 55% and 39% of ultrasounds, respectively. Patients with metabolic symptoms had a nodule identified on ultrasound 43% of the time. Among those referred for high risk factors, 57% had a nodule present.
Overall, only 27% of ultrasounds identified a thyroid nodule that was recommended for a biopsy. Again, those referred because of an incidental imaging finding had the highest percentage (55%), followed by those referred for a suspected palpable nodule (21%), high risk factors (20%), combined indications (16%), metabolic symptoms (10%), and compressive symptoms (6%).
Mean nodule size was largest among the patients referred for incidentalomas (2.4 cm), whereas all the other groups had mean nodule sizes between 1.2 cm and 1.8 cm, a significant difference (P < .05). The median size of nodules among those referred to ultrasound for a suspected palpable nodule was 1.4 cm.
“That’s pretty small. It would have had to be in the front of the thyroid where they could actually touch it. I would argue that the number of clinicians who actually palpated something was smaller. We’ve done several projects looking at how small a nodule a clinician can actually feel in the thyroid gland from the neck. It turns out we’re pretty bad at physical examination of the thyroid. This paper kind of reinforces that,” Dr. Francis said in an interview.
Patients with incidental nodules were over 10 times more likely to have a nodule found on an ultrasound than those referred for a suspected palpable nodule on exam (odds ratio [OR], 10.6). Conversely, those referred for compressive symptoms were half as likely to have an identifiable nodule compared with those referred for physical exam findings (OR, 0.5).
The odds of finding a nodule increased with age, especially for those aged ≥ 65 years compared with those younger than 45 years (OR, 3.6). Women were twice as likely to have a nodule found on thyroid ultrasound (OR, 2.0). Results were similar for the biopsy-recommended nodules, except that there was no difference between sexes (female vs male OR, 1.2).
Dr. Angell called the study “a very robust comprehensive evaluation,” but also noted that the single center source is a limitation. “It would be nice to have those big databases of national healthcare settings, but getting that granular level of information about why something was done is nearly impossible in that context.”
Dr. Kennedy, Dr. Francis, and Dr. Angell have no disclosures.
A version of this article appeared on Medscape.com.