Revisiting the Natural History of Pulmonary Tuberculosis: A Bayesian Estimation of Natural Recovery and Mortality Rates

Ragonnet, Romain, Flegg, Jennifer A., Brilleman, Samuel L., Tiemersma, Edine W., Melsew, Yayehirad A., McBryde, Emma S., and Trauer, James M. (2021) Revisiting the Natural History of Pulmonary Tuberculosis: A Bayesian Estimation of Natural Recovery and Mortality Rates. Clinical Infectious Diseases, 73 (1). e88-e96.

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Abstract

BACKGROUND: Tuberculosis (TB) natural history remains poorly characterized, and new investigations are impossible as it would be unethical to follow up TB patients without treatment.

METHODS: We considered the reports identified in a previous systematic review of studies from the prechemotherapy era, and extracted detailed data on mortality over time. We used a Bayesian framework to estimate the rates of TB-induced mortality and self-cure. A hierarchical model was employed to allow estimates to vary by cohort. Inference was performed separately for smear-positive TB (SP-TB) and smear-negative TB (SN-TB).

RESULTS: We included 41 cohorts of SP-TB patients and 19 cohorts of pulmonary SN-TB patients in the analysis. The median estimates of the TB-specific mortality rates were 0.389 year-1 (95% credible interval [CrI], .335-.449) and 0.025 year-1 (95% CrI, .017-.035) for SP-TB and SN-TB patients, respectively. The estimates for self-recovery rates were 0.231 year-1 (95% CrI, .177-.288) and 0.130 year-1 (95% CrI, .073-.209) for SP-TB and SN-TB patients, respectively. These rates correspond to average durations of untreated TB of 1.57 years (95% CrI, 1.37-1.81) and 5.35 years (95% CrI, 3.42-8.23) for SP-TB and SN-TB, respectively, when assuming a non-TB-related mortality rate of 0.014 year-1 (ie, a 70-year life expectancy).

CONCLUSIONS: TB-specific mortality rates are around 15 times higher for SP-TB than for SN-TB patients. This difference was underestimated dramatically in previous TB modeling studies, raising concerns about the accuracy of the associated predictions. Despite being less infectious, SN-TB may be responsible for equivalent numbers of secondary infections as SP-TB due to its much longer duration.

Item ID: 70315
Item Type: Article (Research - C1)
ISSN: 1537-6591
Keywords: disease prognosis, epidemiology, mortality rates, natural history, tuberculosis
Copyright Information: © The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved
Funders: National Health and Medical Research Council (NHMRC)
Projects and Grants: NHMRC Early Career Fellowship, NHMRC (grant number 1144570)
Date Deposited: 05 Apr 2022 04:24
FoR Codes: 49 MATHEMATICAL SCIENCES > 4901 Applied mathematics > 490102 Biological mathematics @ 30%
42 HEALTH SCIENCES > 4202 Epidemiology > 420205 Epidemiological modelling @ 70%
SEO Codes: 20 HEALTH > 2004 Public health (excl. specific population health) > 200404 Disease distribution and transmission (incl. surveillance and response) @ 80%
20 HEALTH > 2002 Evaluation of health and support services > 200205 Health policy evaluation @ 20%
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