A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.

<h4>Background</h4>In highly resource-limited settings, many clinics lack same-day microbiological testing for active tuberculosis (TB). In these contexts, risk of pretreatment loss to follow-up is high, and a simple, easy-to-use clinical risk score could be useful.<h4>Methods and...

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Main Authors: Yeonsoo Baik, Hannah M Rickman, Colleen F Hanrahan, Lesego Mmolawa, Peter J Kitonsa, Tsundzukana Sewelana, Annet Nalutaaya, Emily A Kendall, Limakatso Lebina, Neil Martinson, Achilles Katamba, David W Dowdy
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2020-11-01
Series:PLoS Medicine
Online Access:https://doi.org/10.1371/journal.pmed.1003420
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author Yeonsoo Baik
Hannah M Rickman
Colleen F Hanrahan
Lesego Mmolawa
Peter J Kitonsa
Tsundzukana Sewelana
Annet Nalutaaya
Emily A Kendall
Limakatso Lebina
Neil Martinson
Achilles Katamba
David W Dowdy
author_facet Yeonsoo Baik
Hannah M Rickman
Colleen F Hanrahan
Lesego Mmolawa
Peter J Kitonsa
Tsundzukana Sewelana
Annet Nalutaaya
Emily A Kendall
Limakatso Lebina
Neil Martinson
Achilles Katamba
David W Dowdy
author_sort Yeonsoo Baik
collection DOAJ
description <h4>Background</h4>In highly resource-limited settings, many clinics lack same-day microbiological testing for active tuberculosis (TB). In these contexts, risk of pretreatment loss to follow-up is high, and a simple, easy-to-use clinical risk score could be useful.<h4>Methods and findings</h4>We analyzed data from adults tested for TB with Xpert MTB/RIF across 28 primary health clinics in rural South Africa (between July 2016 and January 2018). We used least absolute shrinkage and selection operator regression to identify characteristics associated with Xpert-confirmed TB and converted coefficients into a simple score. We assessed discrimination using receiver operating characteristic (ROC) curves, calibration using Cox linear logistic regression, and clinical utility using decision curves. We validated the score externally in a population of adults tested for TB across 4 primary health clinics in urban Uganda (between May 2018 and December 2019). Model development was repeated de novo with the Ugandan population to compare clinical scores. The South African and Ugandan cohorts included 701 and 106 individuals who tested positive for TB, respectively, and 686 and 281 randomly selected individuals who tested negative. Compared to the Ugandan cohort, the South African cohort was older (41% versus 19% aged 45 years or older), had similar breakdown of biological sex (48% versus 50% female), and had higher HIV prevalence (45% versus 34%). The final prediction model, scored from 0 to 10, included 6 characteristics: age, sex, HIV (2 points), diabetes, number of classical TB symptoms (cough, fever, weight loss, and night sweats; 1 point each), and >14-day symptom duration. Discrimination was moderate in the derivation (c-statistic = 0.82, 95% CI = 0.81 to 0.82) and validation (c-statistic = 0.75, 95% CI = 0.69 to 0.80) populations. A patient with 10% pretest probability of TB would have a posttest probability of 4% with a score of 3/10 versus 43% with a score of 7/10. The de novo Ugandan model contained similar characteristics and performed equally well. Our study may be subject to spectrum bias as we only included a random sample of people without TB from each cohort. This score is only meant to guide management while awaiting microbiological results, not intended as a community-based triage test (i.e., to identify individuals who should receive further testing).<h4>Conclusions</h4>In this study, we observed that a simple clinical risk score reasonably distinguished individuals with and without TB among those submitting sputum for diagnosis. Subject to prospective validation, this score might be useful in settings with constrained diagnostic resources where concern for pretreatment loss to follow-up is high.
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spelling doaj.art-ef6ca963c79f42a78a6ebc5d95a69ad52022-12-21T19:59:13ZengPublic Library of Science (PLoS)PLoS Medicine1549-12771549-16762020-11-011711e100342010.1371/journal.pmed.1003420A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.Yeonsoo BaikHannah M RickmanColleen F HanrahanLesego MmolawaPeter J KitonsaTsundzukana SewelanaAnnet NalutaayaEmily A KendallLimakatso LebinaNeil MartinsonAchilles KatambaDavid W Dowdy<h4>Background</h4>In highly resource-limited settings, many clinics lack same-day microbiological testing for active tuberculosis (TB). In these contexts, risk of pretreatment loss to follow-up is high, and a simple, easy-to-use clinical risk score could be useful.<h4>Methods and findings</h4>We analyzed data from adults tested for TB with Xpert MTB/RIF across 28 primary health clinics in rural South Africa (between July 2016 and January 2018). We used least absolute shrinkage and selection operator regression to identify characteristics associated with Xpert-confirmed TB and converted coefficients into a simple score. We assessed discrimination using receiver operating characteristic (ROC) curves, calibration using Cox linear logistic regression, and clinical utility using decision curves. We validated the score externally in a population of adults tested for TB across 4 primary health clinics in urban Uganda (between May 2018 and December 2019). Model development was repeated de novo with the Ugandan population to compare clinical scores. The South African and Ugandan cohorts included 701 and 106 individuals who tested positive for TB, respectively, and 686 and 281 randomly selected individuals who tested negative. Compared to the Ugandan cohort, the South African cohort was older (41% versus 19% aged 45 years or older), had similar breakdown of biological sex (48% versus 50% female), and had higher HIV prevalence (45% versus 34%). The final prediction model, scored from 0 to 10, included 6 characteristics: age, sex, HIV (2 points), diabetes, number of classical TB symptoms (cough, fever, weight loss, and night sweats; 1 point each), and >14-day symptom duration. Discrimination was moderate in the derivation (c-statistic = 0.82, 95% CI = 0.81 to 0.82) and validation (c-statistic = 0.75, 95% CI = 0.69 to 0.80) populations. A patient with 10% pretest probability of TB would have a posttest probability of 4% with a score of 3/10 versus 43% with a score of 7/10. The de novo Ugandan model contained similar characteristics and performed equally well. Our study may be subject to spectrum bias as we only included a random sample of people without TB from each cohort. This score is only meant to guide management while awaiting microbiological results, not intended as a community-based triage test (i.e., to identify individuals who should receive further testing).<h4>Conclusions</h4>In this study, we observed that a simple clinical risk score reasonably distinguished individuals with and without TB among those submitting sputum for diagnosis. Subject to prospective validation, this score might be useful in settings with constrained diagnostic resources where concern for pretreatment loss to follow-up is high.https://doi.org/10.1371/journal.pmed.1003420
spellingShingle Yeonsoo Baik
Hannah M Rickman
Colleen F Hanrahan
Lesego Mmolawa
Peter J Kitonsa
Tsundzukana Sewelana
Annet Nalutaaya
Emily A Kendall
Limakatso Lebina
Neil Martinson
Achilles Katamba
David W Dowdy
A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.
PLoS Medicine
title A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.
title_full A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.
title_fullStr A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.
title_full_unstemmed A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.
title_short A clinical score for identifying active tuberculosis while awaiting microbiological results: Development and validation of a multivariable prediction model in sub-Saharan Africa.
title_sort clinical score for identifying active tuberculosis while awaiting microbiological results development and validation of a multivariable prediction model in sub saharan africa
url https://doi.org/10.1371/journal.pmed.1003420
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