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Pooling of sputum samples to increase tuberculosis diagnostic capacity in Brazil during the COVID-19 pandemic

Santos, Victor Santana, Allgayer, Manuela Filter, Kontogianni, Konstantina, Rocha, José Erinaldo, Pimentel, Beatriz Jatobá, Amorim, Maria Telma Pinheiro, Duarte, Morgana Valnia Simões Cavalcanti, Ferreira, Polyanne de Melo, Moura, Luciana Coelho Leite, Santos de Lima, Victoria Paulino, Guimarães, Larissa Cândido, Dodd, James, Creswell, Jacob and Cuevas, Luis ORCID: (2023) 'Pooling of sputum samples to increase tuberculosis diagnostic capacity in Brazil during the COVID-19 pandemic'. International Journal of Infectious Diseases, Vol 129, pp. 10-14.

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We assessed whether combining (pooling) four individual's samples and testing with Xpert Ultra has the same accuracy as testing samples individually, as a more efficient testing method.

We conducted a cross-sectional study of individuals with presumptive TB attending primary health care or general hospital facilities in Alagoas, Brazil. Sputum samples of four consecutive individuals were pooled and the pool and individual samples were tested with Xpert Ultra. The agreement of the tests was compared using kappa statistics. We estimated the sensitivity and specificity of pooling using the individual test as the reference standard and potential cartridge savings.

Three hundred and ninety-six participants were tested. Ninety-five (24.0%) individual samples were MTB-positive, 300 (75.8%) MTB-not detected, including 20 MTB-trace, and one reported an error. Ninety-nine pools of four samples were tested, of which 62 (62.6%) had MTB-detected and 37 (37.4%) MTB-not detected, including six (6.1%) with MTB-trace. The agreement of individual and pooled testing was 96.0%. Pooling had sensitivity of 95.0% (95%CI 86.9%–99%), specificity of 97.1% (95%CI 85.1%–99.9%) and Kappa of 0.913. The method saved 12.4% of cartridge costs.

The pooled testing of specimens had a high level of agreement with individual testing. Pooling of samples for testing improves the efficiency of testing, potentially enabling the screening and testing of larger numbers of people more cost-effectively.

Item Type: Article
Subjects: QY Clinical Pathology > Diagnostic Tests > QY 120 Sputum
WA Public Health > WA 30 Socioeconomic factors in public health (General)
WF Respiratory System > Tuberculosis > WF 220 Diagnosis. Prognosis
Faculty: Department: Clinical Sciences & International Health > Clinical Sciences Department
Clinical Sciences & International Health > International Public Health Department
Digital Object Identifer (DOI):
SWORD Depositor: JISC Pubrouter
Depositing User: JISC Pubrouter
Date Deposited: 02 Feb 2023 11:57
Last Modified: 13 Mar 2023 09:30


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