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Finding Children With Active Tuberculosis: What is the Number Needed to Screen?

March 31, 2023

In a recently released issue of Pediatrics, Dr. Katherine O. Robsky and colleagues from Johns Hopkins University conducted a systematic review to estimate the number of children who would need to be screened in order to find a single child with active tuberculosis (TB) in need of treatment (10.1542/peds.2022-059189). The authors considered different health care settings, differing regional tuberculosis burden levels, and different screening strategies (such as symptoms of chronic cough or weight loss with and without radiograph). They focused on active case finding (ACF) strategies, defined as systematic screening for TB applied outside of health facilities, as compared to identifying those who present themselves to a healthcare setting for treatment. An accompanying commentary by Dr. Helen Jenkins of Boston University School of Public Health and Dr. Jeffrey Starke of Baylor College of Medicine adds to understanding of this challenging and important topic (10.1542/peds.2022-059849).

Tuberculosis is a major cause of illness and death globally, with over 1 million children affected according to 2020 data in the main article. While treatment of TB in children and youth is generally very successful, evidence shows that disease is widely under-recognized, especially in those who are under 5 years of age, and hence many children go untreated, with associated high mortality rates.1

The World Health Organization recommends screening close contacts and household contacts of those with TB, as well as children living with HIV who visit a health facility; the recommendation was ready for an update,2 and this systematic review fills that gap. The authors located 27,221 titles and identified 31 eligible articles that addressed ACF for TB in children. Most studies were conducted in areas with moderate or high TB burden (28/31) and several (8/31) focused exclusively on children with HIV. The systematic review results are fascinating. For example, the number needed to screen (NNS), using only an abnormal chest radiograph to screen, ranged from 17 (among children < 15 years of age, living with HIV and residing in moderate to high TB burden countries) all the way up to 30,891 among children without HIV living in moderate to low burden countries. Generally, the authors found that screening those under 5 years of age living with HIV in a healthcare setting led to the lowest NNS. But using differing strategies in differing locations yielded differing NNS results that I hope you will read to better understand the complex but well explained results.

While lauding the value and quality of this systematic review, Jenkins and Stark note in their commentary that a lack of high-quality, appropriately powered, and setting-specific studies limited the ability of Robsky et al to draw conclusions. The challenge of diagnosing TB in young children complicates all studies, since there is no gold standard for diagnosis, and neither symptoms nor sputum nor radiographs are definitive, and the risk for disseminated disease must always be balanced against the risks of over-diagnosis and unneeded treatment. More research is needed, and both the careful systematic review by Robsky et al and accompanying commentary by Jenkins and Starke provide guidance with respect to potentially high yield approaches. Let us know what you learned from these two great articles!  

Image courtesy of Red Book.


  1. Dodd PJ, Yuen CM, Sismanidis C, Seddon JA, Jenkins HE. The global burden of tuberculosis mortality in children: a mathematical modelling study. Lancet Glob Health. 2017 Sep;5(9):e898-e906. doi: 10.1016/S2214-109X(17)30289-9. PMID: 28807188; PMCID: PMC5556253
  2. WHO consolidated guidelines on tuberculosis. Module 5: management of tuberculosis in children and adolescents. (2022)
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