<p><strong>Context: </strong>Thyroid nodules are increasingly recognized in children and are associated with a greater risk for thyroid cancer compared to adults. Thyroid ultrasound is the favored tool for evaluation of thyroid nodules; however, there are limited data regarding the accuracy of thyroid ultrasound to confirm features associated with a low risk of thyroid cancer in children.</p>

<p><strong>Objectives: </strong>We examined whether thyroid ultrasound is capable of accurately identifying thyroid nodules at a low risk of malignancy in children.</p>

<p><strong>Design and Setting: </strong>Using a retrospective cohort study design, we identified all children age ≤ 18 years with thyroid nodules and adequate follow up. Ultrasound images were reviewed independently by two blinded expert radiologists and ultrasound characteristics were analyzed to determine optimal predictive value and reliability.</p>

<p><strong>Patients and Results: </strong>417 subjects were found to have thyroid nodules and 152 subjects had adequate follow up; 59 (38.8%) of these were diagnosed with thyroid cancer. 236 individual nodules were evaluated. Features most consistent with benign nodules included small size, isoechoic echogenicity, partially cystic structure, sharp or non-infiltrative margins, absent Doppler flow and absent calcifications. Significant variability was found between expert interpretations of ultrasound features. Thyroid nodule composition appears to be the most sensitive and reliable feature for stratifying risk of thyroid cancer. Cumulatively, ultrasound accurately identified benign thyroid nodules in 80.9% (95% CI 74, 86.6%) of subjects.</p>

<p><strong>Conclusions: </strong>Ultrasonography is useful for the evaluation of thyroid nodules, but we found no combination of ultrasound features sufficient to exclude thyroid cancer without a biopsy.</p>

<p><strong>OBJECTIVE: </strong>To identify the prevalence of high HIV transmission potential in a cohort of youth living with HIV (YLWH), and determine the impact of insurance coverage on potential for HIV transmission.</p>

<p><strong>DESIGN: </strong>Retrospective cohort study of antiretroviral therapy (ART)-treated YLWH at a US adolescent HIV clinic, 2002-2015.</p>

<p><strong>METHODS: </strong>The primary exposure was presence or absence of insurance, defined as private, public or pharmacy-only coverage. The primary outcome was high HIV transmission potential, defined as time-concurrent incident bacterial STI (gonorrhea, chlamydia or syphilis) and HIV RNA greater than 1500 copies/ml. Marginal structural models adjusting for baseline demographic covariates, prior history of STI and time-varying retention in care assessed the relationship between insurance status and HIV transmission potential.</p>

<p><strong>RESULTS: </strong>Participants (n = 240) were followed for a median of 22 (IQR 8.1-49) months after ART initiation, and were predominately African-American men and transgender women who have sex with men, with a median age at HIV diagnosis of 19 years (IQR 17-21). We identified 37 (15%) participants with at least one episode of high HIV transmission potential. Insurance coverage was associated with a greater than 50% lower odds of high HIV transmission potential (aOR 0.46, 95% CI 0.26-0.84), and history of STI at or before entry to HIV care conferred more than three-fold higher odds of high transmission potential (aOR 3.21, 95% CI 1.55-6.63).</p>

<p><strong>CONCLUSION: </strong>We found 17% of YLWH to have episodic high HIV transmission potential despite receiving ART. Insurance coverage, including pharmacy-only benefits, was protective against transmission risk, suggesting a pivotal role for universal ART coverage in treatment as prevention.</p>