Interferon-G Release Assays in Children ,15 Years of Age Amina Ahmed, MD,A Pei-Jean I
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Interferon-g Release Assays in Children ,15 Years of Age Amina Ahmed, MD,a Pei-Jean I. Feng, MPH,b James T. Gaensbauer, MD, MScPH,c Randall R. Reves, MD, MSc,c Renuka Khurana, MD, MPH,d Katya Salcedo, MPH,e Rose Punnoose, MPH,f Dolly J. Katz, PhD,b for the TUBERCULOSIS EPIDEMIOLOGIC STUDIES CONSORTIUM OBJECTIVES: The tuberculin skin test (TST) has been preferred for screening young children for abstract latent tuberculosis infection (LTBI) because of concerns that interferon-g release assays (IGRAs) may be less sensitive in this high-risk population. In this study, we compared the predictive value of IGRAs to the TST for progression to tuberculosis disease in children, including those ,5 years old. METHODS: Children ,15 years old at risk for LTBI or progression to disease were tested with TST, QuantiFERON-TB Gold In-Tube test (QFT-GIT), and T-SPOT.TB test (T-SPOT) and followed actively for 2 years, then with registry matches, to identify incident disease. RESULTS: Of 3593 children enrolled September 2012 to April 2016, 92% were born outside the United States; 25% were ,5 years old. Four children developed tuberculosis over a median 4.3 years of follow-up. Sensitivities for progression to disease for TST and IGRAs were low (50%–75%), with wide confidence intervals (CIs). Specificities for TST, QFT-GIT, and T-SPOT were 73.4% (95% CI: 71.9–74.8), 90.1% (95% CI: 89.1–91.1), and 92.9% (95% CI: 92.0–93.7), respectively. Positive and negative predictive values for TST, QFT-GIT, and T-SPOT were 0.2 (95% CI: 0.1–0.8), 0.9 (95% CI: 0.3–2.5), and 0.8 (95% CI: 0.2–2.9) and 99.9 (95% CI: 99.7–100), 100 (95% CI: 99.8–100), and 99.9 (95% CI: 99.8–100), respectively. Of 533 children with TST-positive, IGRA-negative results not treated for LTBI, including 54 children ,2 years old, none developed disease. CONCLUSIONS: Although both types of tests poorly predict disease progression, IGRAs are no less predictive than the TST and offer high specificity and negative predictive values. Results from this study support the use of IGRAs for children, especially those who are not born in the United States. ’ aLevine Children’s Hospital at Atrium Health, Charlotte, North Carolina; bDivision of Tuberculosis Elimination, WHAT S KNOWN ON THIS SUBJECT: The tuberculin skin Centers for Disease Control and Prevention, Atlanta, Georgia; cDenver Health and Hospitals, Denver, Colorado; test (TST) has been the preferred test for screening young dMaricopa County Department of Public Health, Phoenix, Arizona; eTuberculosis Control Branch, California children for latent tuberculosis infection because of Department of Public Health, Richmond, California; and fNorthrop Grumman, Atlanta, Georgia concerns that interferon-g release assays (IGRAs) could The findings and conclusions in this report are those of the authors and do not necessarily miss infections in this high-risk population. represent the official position of the Centers for Disease Control and Prevention or the authors’ WHAT THIS STUDY ADDS: In this cohort of 3593 children affiliated institutions. followed for a median 4.3 years, IGRAs had higher Dr Ahmed contributed to the design of the study, collected data, provided input for the analyses, specificities than TST and high negative predictive value. and drafted the initial manuscript; Mrs Feng contributed to the design of the study and data None of 533 untreated children who had positive TST collection instruments, supervised data collection, and conducted the analyses; Dr Gaensbauer results and negative IGRA results, including 54 children collected data and provided input for the analyses; Dr Katz contributed to the conceptualization and ,2 years old, developed tuberculosis disease. design of the study, supervised data collection, and provided input for the analyses; Drs Khurana and Reves contributed to the design of the study, collected data, and provided input for the To cite: Ahmed A, Feng PI, Gaensbauer JT, et al. analyses; Mrs Punnoose contributed to the supervision of data collection and conducted analyses; Interferon-g Release Assays in Children ,15 Years of Ms Salcedo collected data and provided input for the analyses; and all authors (Continued) Age. Pediatrics. 2020;145(1):e20191930 Downloaded from www.aappublications.org/news by guest on October 1, 2021 PEDIATRICS Volume 145, number 1, January 2020:e20191930 ARTICLE Reactivation of latent tuberculosis Pediatrics amended the age for the September 2012 to April 2016 infection (LTBI) accounts for .80% preferred use of TST to those constituted the study population. of tuberculosis cases in the United ,2 years old.14,15 Questions remain, A child was eligible for enrollment if States.1 Because treatment of LTBI however, about which test is best for she or he was (1) a close contact ($8 can prevent progression to disease, screening children, especially hours in a week) with an individual detection and treatment of LTBI is children not born in the United States with infectious tuberculosis who (a) essential to tuberculosis elimination in whom use of TST may result in was part of an ongoing contact in the United States.2 Children are overdiagnosis and overtreatment of investigation and (b) had either a priority for LTBI screening because LTBI.15 The only reference standard a positive culture result or a negative once infected (1) they are at high risk for LTBI is eventual development of culture result but positive smear of progression to disease in the culture-proven disease. The positive result and positive nucleic acid absence of treatment, (2) they are predictive value (PPV) of TST for amplification test result, (2) born in more likely to develop severe disease progression to disease has been a country whose population in the (eg, meningeal and miliary established by multiple longitudinal – United States had a high ($100 cases tuberculosis), and (3) those who do studies.16 18 The predictive value of per 100 000 population) rate of not develop disease in childhood are IGRAs in children is unclear because tuberculosis22 (Supplemental a reservoir for future tuberculosis longitudinal studies involving IGRAs Table 6), (3) a recent arrival (#5 cases.3,4 are scarce. There have been years) from a country whose numerous requests for a prospective The optimal testing strategy for LTBI population in the United States had cohort study comparing IGRAs to TST in children is unclear. The tuberculin a moderate (10–99 cases per 100 000 in regard to their ability to predict skin test (TST) has been in use for population) rate of tuberculosis22 progression to disease in this more than a century, but its – (Supplemental Table 7), (4) population.19 21 For clinicians, an specificity is limited by cross- a member of a local population with important outcome from such studies reactivity of TST antigens with those documented LTBI prevalence $25%, would be the negative predictive of nontuberculous mycobacteria5,6 or (5) a person with HIV infection. value (NPV) of an IGRA result for and the bacillus Calmette-Guerin Participants enrolled as members of subsequent development of (BCG) vaccine, given to newborns in local populations with LTBI tuberculosis disease. .80% of countries worldwide.7 prevalence $25% were homeless or Interferon-g release assays (IGRAs), We analyzed data from children born in Mexico. Results for homeless available since 2000, measure in vitro enrolled in a large prospective persons were reported as a separate IFN-g production by T lymphocytes longitudinal study to compare the category; those for Mexican-born after stimulation with Mycobacterium predictive value of commercially persons were included in results for tuberculosis–specific antigens not available tests. Our objective was to participants not born in the United found in any BCG strain or in most identify optimal testing strategies for States. the detection of LTBI in children nontuberculous mycobacteria. The 2 We excluded from this analysis overall, children ,5 years old, and commercially available IGRAs, results for participants who (1) were 8 TB children born outside of the United QuantiFERON test and T-SPOT. diagnosed with tuberculosis disease 9 States. test (T-SPOT), offer additional during screening, (2) were enrolled advantages of a single visit for as contacts of source cases with phlebotomy and results that avoid METHODS negative culture, smear, and nucleic variability because of subjectivity in fi M 10 acid ampli cation test results for interpretation observed with TSTs. Study Population tuberculosis, (3) lacked valid TST Current US guidelines recommend The Tuberculosis Epidemiologic results, or (4) did not have at least 1 IGRAs for children $5 years old, for Studies Consortium (TBESC), funded valid IGRA result. The study was whom the risk of progression to by the Centers for Disease Control approved by each site’s institutional disease is the same as for adults.11 and Prevention (CDC), is review board (IRB), or the site relied TST is recommended for younger a partnership of academic and public on the CDC IRB. All participants had children, in whom the risk of health programs in 11 states. TBESC- parental consent; written assent was progression to tuberculosis is 4 to affiliated clinics recruited individuals obtained as required by 5 times higher, primarily on the basis at risk for LTBI or progression to individual IRBs. of studies that suggest diminished tuberculosis to assess the ability of IGRA sensitivity in this age TST and IGRAs to predict tuberculosis Study Procedures group.10,12,13 On the basis of more disease. Children who were Study personnel collected recent data, the American Academy of ,15 years old and enrolled from demographic and LTBI-related risk Downloaded from www.aappublications.org/news by guest on October 1, 2021 2 AHMED et al information using a standardized disease registries; the last registry RESULTS questionnaire.