Transition from Restrictive to Obstructive Lung Function Impairment During Treatment and Follow-Up of Active Tuberculosis

Abstract

Background

Pulmonary tuberculosis (PTB) is associated with many forms of chronic lung disease including the development of chronic airflow obstruction (AFO). However, the nature, evolution and mechanisms responsible for the AFO after PTB are poorly understood. The aim of this study was to examine the progression of changes in lung physiology in patients treated for PTB.

Methods

Immunocompetent, previously healthy, adult patients receiving ambulatory treatment for a first episode of tuberculosis were prospectively followed up with serial lung physiology and quantitative computed tomography (CT) lung scans performed at diagnosis of tuberculosis, 2, 6, 12 and 18 months during and after the completion of treatment.

Results

Forty-nine patients (median age 26 years; 37.2% males) were included, and 43 were studied. During treatment, lung volumes improved and CT fibrosis scores decreased, but features of AFO and gas trapping emerged, while reduced diffusing capacity (DLco) seen in a majority of patients persisted. Significant increases in total lung capacity (TLC) by plethysmography were seen in the year following treatment completion (median change 5.9% pred., P<0.01) and were driven by large increases in residual volume (RV) (median change +19%pred., P<0.01) but not inspiratory capacity (IC; P=0.41). The change in RV/TLC correlated with significant progression of radiological gas trapping after treatment (P=0.04) but not with emphysema scores. One year after completing treatment, 18.6% of patients had residual restriction (total lung capacity, TLC <80%pred), 16.3% had AFO, 32.6% had gas trapping (RV/TLC>45%), and 78.6% had reduced DLco.

Conclusion

Simple spirometry alone does not fully reveal the residual respiratory impairments resulting after a first episode of PTB. Changes in physiology evolve after treatment completion, and these findings when taken together, suggest emergence of gas trapping after treatment likely caused by progression of small airway pathology during the healing process.

Journal

Journal ID (nlm-ta): Int J Chron Obstruct Pulmon Dis

Journal ID (iso-abbrev): Int J Chron Obstruct Pulmon Dis

Journal ID (publisher-id): COPD

Journal ID (pmc): copd

Title: International Journal of Chronic Obstructive Pulmonary Disease

Publisher: Dove

ISSN (Print): 1176-9106

ISSN (Electronic): 1178-2005

Publication date (Electronic): 11 May 2020

Publication date Collection: 2020

Volume: 15

Pages: 1039-1047

Affiliations

[1 ]Division of Pulmonology, Department of Medicine, Stellenbosch University , Cape Town, South Africa

[2 ]University of Cape Town Lung Institute, and Division of Pulmonology, Department of Medicine, University of Cape Town , Cape Town, South Africa

[3 ]DST/NRF Centre of Excellence for Biomedical Tuberculosis Research; South African Medical Research Council Centre for Tuberculosis Research; Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University , Cape Town, South Africa

[4 ]Center for Computer Visions and Imaging Biomarkers, Department of Radiology, David Geffen School of Medicine, University of California , Los Angeles, CA, USA

[5 ]Department of Biostatistics, Fielding School of Public Health, University of California , Los Angeles, CA, USA

[6 ]Departments of Medicine and Physiology, David Geffen School of Medicine, University of California , Los Angeles, CA, USA

Author notes

Correspondence: Brian W Allwood Division of Pulmonology, Department of Medicine, Stellenbosch University , Rm 3013 3rd Floor; Clinical Building; Francie Van Zijl Drive; Medical School, Tygerberg7505, South Africa Email [e-mail]

Article

Publisher ID: 219731

DOI: 10.2147/COPD.S219731

PMC ID: 7227812

Copyright statement: © 2020 Allwood et al.

License:

This work is published and licensed by Dove Medical Press Limited. The full terms of this license are available at https://www.dovepress.com/terms.php and incorporate the Creative Commons Attribution – Non Commercial (unported, v3.0) License ( http://creativecommons.org/licenses/by-nc/3.0/). By accessing the work you hereby accept the Terms. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed. For permission for commercial use of this work, please see paragraphs 4.2 and 5 of our Terms ( https://www.dovepress.com/terms.php).

Page count

Figures: 4, Tables: 3, References: 20, Pages: 9

Funding

Funding received from the University of Cape Town Lung Institute for funding the radiology component and Global Alliance for TB Drug Development for access to their bio-storage cohort. E.M. is funded by a Strategic Health Innovation Partnership (SHIP) grant from the South African (SA) Department of Science and Technology (DST) and SA Medical Research Council (SAMRC) to the South African Tuberculosis Bioinformatics Initiative (SATBBI), and E.B. received funding from the National Research Foundation (NRF).

Categories

Subject: Original Research