US guidelines recommend interferon gamma release assays (IGRAs) for diagnosis of tuberculosis infection in children. In this retrospective cohort study, IGRA use in children 2–17 years of age increased substantially between 2015 and 2021. Testing in inpatient/subspecialty settings (vs. primary care), public (vs. private) insurance, lower age and non-English preferred language were associated with increased odds of receiving an IGRA.

Background: Interferon-gamma release assays (IGRAs) are approved for children ≥2 years old to aid in diagnosis of Mycobacterium tuberculosis (TB) infection and disease. Tuberculin skin tests (TSTs) continue to be the recommended method for diagnosis of TB infection in children <2 years, in part due to limited data and concern for high rates of uninterpretable results. Methods: We performed a retrospective cohort study of IGRA use in patients <2 years old in 2 large Boston healthcare systems. The primary outcome was the proportion of valid versus invalid/indeterminate IGRA results. Secondary outcomes included concordance of IGRAs with paired TSTs and trends in IGRA usage over time. Results: A total of 321 IGRA results were analyzed; 308 tests (96%) were valid and 13 (4%) were invalid/indeterminate. Thirty-seven IGRAs were obtained in immunocompromised patients; the proportion of invalid/indeterminate results was significantly higher among immunocompromised (27%) compared with immunocompetent (1%) patients (P < 0.001). Paired IGRAs and TSTs had a concordance rate of 64%, with most discordant results in bacille Calmette-Guérin–vaccinated patients. The proportion of total TB tests that were IGRAs increased over the study period (Pearson correlation coefficient 0.85, P < 0.001). Conclusions: The high proportion of valid IGRA test results in patients <2 years of age in a low TB prevalence setting in combination with the known logistical and interpretation challenges associated with TSTs support the adoption of IGRAs for this age group in certain clinical scenarios. Interpretation of IGRAs, particularly in immunocompromised patients, should involve consideration of the broader clinical context.

Background Location and type of clinic where pediatric latent TB infection (LTBI) care is provided are associated with treatment completion and retention in care. Prior research has not evaluated joint clinical management occurring between care settings. Understanding care transfer dynamics and accessibility of clinics can inform pediatric LTBI care service delivery. Methods We conducted a retrospective cohort study of LTBI in children 0-17 years old who were prescribed outpatient treatment in two Boston-area health systems from 2017-2019. We defined “initial clinical setting” (categorized as primary care or TB/infectious diseases clinic) as the location where the first LTBI medication was prescribed. Through chart review, we determined if care was transferred to a different (“final”) clinic setting during treatment. We calculated driving time between a child’s home address and initial and final treatment clinics. The primary outcome was frequency of care transfer after starting treatment. In a secondary analysis, we used two multivariable logistic regression models (adjusted for age, sex, and use of rifamycin-based treatment) to evaluate associations between completion and distance to and type of initial and final treatment clinic. Results We identified 142 children who started LTBI treatment as outpatients; 110 started treatment in primary care clinics and 32 in TB/infectious diseases clinics. Overall, 20/142 (14%) transferred TB care to a different clinic after starting treatment. A total of 101/142 (71%) patients completed treatment. Neither initial treatment location nor driving time to initial clinic were significantly associated with treatment completion (Table 1). However, final treatment in a TB clinic was associated with higher odds of treatment completion than final treatment in a primary care clinic (aOR 2.71 [95%CI 1.06-6.91], P=0.04); time to clinic was not associated with completion (Table 2). Figure 1.Patient transfers after starting LTBI treatment.Table 1.Initial treatment location: Univariable and multivariable analysis of factors associated with treatment completion.1Adjusted for time to clinic and location of initial treatment as well as age, sex, and use of rifamycin-based treatment.Table 2.Final treatment location: Univariable and multivariable analysis of factors associated with treatment completion.1Adjusted for time to clinic and location of final treatment as well as age, sex, and use of rifamycin-based treatment. Conclusion Among children with LTBI in a large metropolitan area, more patients received treatment in primary care clinics than in TB clinics. Care transfers were relatively uncommon after starting treatment. A TB clinic as a final treatment location was associated with increased odds of treatment completion. Disclosures Jessica Haberer, MD, MS, Merck: Advisor/Consultant|Natera: Stocks/Bonds.

Background The American Academy of Pediatrics recommends use of Interferon-Gamma Release Assays (IGRAs) to diagnose tuberculosis (TB) infection in patients ≥2 years old. However, IGRAs are not currently recommended in younger patients due to limited data and concerns of invalid/indeterminate test results, which occur if there is a positive or negative control failure. We sought to characterize the patterns of IGRA use in clinical practice and results of IGRAs in patients &lt; 2 years old. Methods We conducted a retrospective cohort study of children &lt; 2 years old at two large health systems in the Boston area who had IGRA and/or tuberculin skin test (TST) performed from October 1, 2015 – January 31, 2021. We reviewed medical records to determine IGRA test type, IGRA result (positive, negative, invalid/indeterminate) and location of testing (outpatient primary care, outpatient subspecialty, inpatient). We summarized test interpretability, location, and changes in proportion of IGRA vs. TST. Results We identified 330 IGRA (268 T-SPOT.TB, 62 QuantiFERON Gold) and 2029 TST results among 1982 patients who were &lt; 2 years old (range: 11 days – 1.9 years). Monthly proportion of IGRAs among all TB tests ordered increased from 2015 to 2021 (Figure 1) (Pearson correlation coefficient 0.85, P &lt; 0.001). Among IGRA results, 314 (95%) were negative, 3 (1%) were positive, and 13 (4%) were invalid/indeterminate (11 T-SPOT.TB, 2 QuantiFERON Gold). Of 324 IGRA tests for which testing location was known, 233 (72%) and 91 (28%) were ordered in outpatient and inpatient settings, respectively. Of tests in outpatient settings, 132 (57%) were ordered in primary care offices, 53 (23%) were ordered in subspecialist offices, and 48 (21%) were obtained in outpatient labs of unidentified clinics. Tuberculosis infection tests and proportion IGRA. Total number of tests and proportion of IGRA:TST obtained by month, from October 2015-January 2021. Conclusion While most TB infection tests in this age group were TSTs, the monthly proportion of tests that were IGRAs increased over time between 2015-2021. IGRAs were obtained in varied clinical settings. In this low-burden setting, rates of invalid/indeterminate IGRAs were low among children &lt; 2 years old, which suggests that IGRAs are reasonable TB testing options for patients &lt; 2 years old, and may be preferred given limitations of TSTs. Disclosures Gabriella S. Lamb, MD, MPH, Nothing to disclose