Background: Cough frequency, and its duration, is a biomarker that can be used in low-resource settings without the need of laboratory culture and has been associated with transmission and treatment response. Radiologic characteristics associated with increased cough frequency may be important in understanding transmission. The relationship between cough frequency and cavitary lung disease has not been studied. Methods: We analyzed data in 41 adults who were HIV negative and had culture-confirmed, drug-susceptible pulmonary TB throughout treatment. Cough recordings were based on the Cayetano Cough Monitor, and sputum samples were evaluated using microscopic observation drug susceptibility broth culture; among culture-positive samples, bacillary burden was assessed by means of time to positivity. CT scans were analyzed by a US-board-certified radiologist and a computer-automated algorithm. The algorithm evaluated cavity volume and cavitary proximity to the airway. CT scans were obtained within 1 month of treatment initiation. We compared small cavities (≤ 7 mL) and large cavities (> 7 mL) and cavities located closer to (≤ 10 mm) and farther from (> 10 mm) the airway to cough frequency and cough cessation until treatment day 60. Results: Cough frequency during treatment was twofold higher in participants with large cavity volumes (rate ratio [RR], 1.98; P =.01) and cavities located closer to the airway (RR, 2.44; P =.001). Comparably, cough ceased three times faster in participants with smaller cavities (adjusted hazard ratio [HR], 2.89; P =.06) and those farther from the airway (adjusted HR, 3.61;, P =.02). Similar results were found for bacillary burden and culture conversion during treatment. Conclusions: Cough frequency during treatment is greater and lasts longer in patients with larger cavities, especially those closer to the airway.
Bibliographical noteFunding Information:
FUNDING/SUPPORT: This study was funded by the National Institute of Allergy and Infectious Diseases [Grant R21AI094143 to R. H. G.] and Fogarty International Center [Grant D43TW006581 to R. H. G.] at the National Institutes of Health and Grand Challenges Canada [Grant 0539-01-10 to G. C.]. This study also was funded by the Center for Infectious Disease Imaging, the intramural research program of the National Institute of Allergy and Infectious Diseases and the National Institute of Biomedical Imaging and Bioengineering from the National Institutes of Health. Contributions by coauthors were funded as follows: Fogarty International Center at the National Institutes of Health [Grants D43TW001140, D43TW010074 to A. P.; Grant R25TW009340 to D. P. B.; Grant R24TW007988 to J. W. L. and M. A. B.; and Grant D43TW009349 to G. O. L. and G. C.]; Grand Challenges Canada [Grant 0537-01-10 to J. W. L.]; Wellcome Trust [Grant 078067/Z/05/Z to D. A. J. M.; and Grants 105788/Z/14/Z and 201251/Z/16/Z to C. A. E.]; Imperial Biomedical Research Centre to J. S. F., and C. A. E.; Joint Global Health Trials [Grant MR/K007467/1 to C. A. E. and R. H. G.]; Stop TB Partnership’s TB REACH initiative funded by the government of Canada [Grant W5_PER_CDT1_PRISMA to C. A. E.] and Bill & Melinda Gates Foundation [Grant OPP1118545 to C. A. E.]; and Innovation for Health and Development funding C. A. E.. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.
© 2018 The Authors