Smear positivity in paediatric and adult tuberculosis: systematic review and meta-analysis

Abstract

BackgroundTuberculosis (TB) diagnosis continues to rely on sputum smear microscopy in many settings. We conducted a meta-analysis to estimate the percentage of children and adults with tuberculosis that are sputum smear positive.MethodsWe searched PubMed, MEDLINE, Embase, and Global Health databases for studies that included both children and adults with all forms of active TB. The pooled percentages of children and adults with smear positive TB were estimated using the inverse variance heterogeneity model. This review was registered in the PROSPERO database under registration number CRD42015015331.ResultsWe identified 20 studies meeting our inclusion criteria that reported smear positivity for a total of 18,316 children and 162,574 adults from 14 countries. The pooled percentage of paediatric TB cases that were sputum smear positive was 6.8 % (95 % Confidence Interval (CI) 2.2–12.2 %), compared with 52.0 % (95 % CI 40.0–64.0 %) among adult cases. Eight studies reported data separately for children aged 0–4 and 5–14. The percentage of children aged 0–4 that were smear positive was 0.5 % (95 % CI 0.0–1.9 %), compared with 14.0 % (95 % CI 8.9–19.4 %) among children aged 5–14.ConclusionsChildren, especially those aged 0–4, are much less likely to be sputum smear positive than adults. National TB programs relying on sputum smear for diagnosis are at risk of under-diagnosing and underestimating the burden of TB in children.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1617-9) contains supplementary material, which is available to authorized users.

Characterizing Pediatric Tuberculosis with and without Human Immunodeficiency Virus Coinfection in Harare, Zimbabwe

“…This is expected given that children are known to be often paucibacillary and mostly sputum negative, representing a major limitation in studying childhood TB. Kunkel et al 18 also reported a similar low smear positivity rate of 6.6% in children treated for PTB. Our study, therefore, adds to the growing list of research in support of the need for more effective diagnostic criteria for pediatric TB in low-resource settings.…”

The Global Burden of Latent Tuberculosis Infection: A Re-estimation Using Mathematical Modelling

“…A previously published study of childhood tuberculosis [16] characterized this ratio in the modern era by fitting a log-normal distribution to data from reviews of studies in which both ARI and prevalence estimates were available [9,10]. To estimate the proportion of prevalent TB that is smear positive for each country, we averaged estimates of smear positivity for 0–4, 5–14, and ≥15 y age groups from a recent systematic review [17] against the proportion of cases in these age-groups calculated using the model of Dodd et al [16]. To calculate the impact of HIV on the proportion of TB in a country that is smear positive, we first calculated the fraction of prevalent TB in people living with HIV (PLHIV) by adjusting the WHO estimates of HIV prevalence in incident TB for each year using estimates of the duration of prevalence in PLHIV and HIV-uninfected individuals [1].…”

The Clinician's Toolkit: Laboratory Tests in the Diagnosis of Childhood Tuberculosis Infection and Disease

“…Among pediatric participants, older children were more likely to have a positive smear (14%) versus children under the age of 4 (0.5%). 24 The third available stain, the auramine stain, is visible under fluorescent microscopy and is 10% more sensitive than stains visible under conventional light microscopy. 25 After the organisms have been treated with the audomine stain, they glow yellow-orange on a dark background when viewed under fluorescent light.…”