Dynamics of Cough Frequency in Adults Undergoing Treatment for Pulmonary Tuberculosis.
Cough is the major determinant of tuberculosis transmission. Despite this, there is a paucity of information regarding characteristics of cough frequency throughout the day and in response to tuberculosis therapy. Here we evaluate the circadian cycle of cough, cough frequency risk factors, and the impact of appropriate treatment on cough and bacillary load.



We prospectively evaluated human immunodeficiency virus-negative adults (n = 64) with a new diagnosis of culture-proven, drug-susceptible pulmonary tuberculosis immediately prior to treatment and repeatedly until treatment day 62. At each time point, participant cough was recorded (n = 670) and analyzed using the Cayetano Cough Monitor. Consecutive coughs at least 2 seconds apart were counted as separate cough episodes. Sputum samples (n = 426) were tested with microscopic-observation drug susceptibility broth culture, and in culture-positive samples (n = 252), the time to culture positivity was used to estimate bacillary load.



The highest cough frequency occurred from 1 pm to 2 pm, and the lowest from 1 am to 2 am (2.4 vs 1.1 cough episodes/hour, respectively). Cough frequency was higher among participants who had higher sputum bacillary load (P < .01). Pretreatment median cough episodes/hour was 2.3 (interquartile range [IQR], 1.2-4.1), which at 14 treatment days decreased to 0.48 (IQR, 0.0-1.4) and at the end of the study decreased to 0.18 (IQR, 0.0-0.59) (both reductions P < .001). By 14 treatment days, the probability of culture conversion was 29% (95% confidence interval, 19%-41%).



Coughs were most frequent during daytime. Two weeks of appropriate treatment significantly reduced cough frequency and resulted in one-third of participants achieving culture conversion. Thus, treatment by 2 weeks considerably diminishes, but does not eliminate, the potential for airborne tuberculosis transmission.
Escuela Profesional de Medicina, Facultad de Medicina Alberto Hurtado, Universidad Peruana Cayetano Heredia, Lima, Perú.|Laboratorio de Investigación en Enfermedades Infecciosas, Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia.
Alvaro
A
Proaño
Asociación Benéfica PRISMA, Lima, Perú.|Department of General Internal Medicine, Massachusetts General Hospital, Boston, USA.|Innovation For Health And Development, Laboratory of Research and Development,Universidad Peruana Cayetano Heredia, Lima, Peru.
Marjory A
MA
Bravard
Laboratorio de Bioinformática y Biología Molecular, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú.|Instituto Nacional de Salud del Niño San Borja, Lima, Perú.
José W
JW
López
Department of Global Community Health and Behavioral Sciences, Tulane University, New Orleans, Louisiana.
Gwenyth O
GO
Lee
Division of Epidemiology and Biostatistics, Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson.
David
D
Bui
Innovation For Health And Development, Laboratory of Research and Development,Universidad Peruana Cayetano Heredia, Lima, Peru.|Infectious Diseases and Immunity and Wellcome Trust Imperial College Centre for Global Health Research, Imperial College London, United Kingdom.
Sumona
S
Datta
Department of Global Community Health and Behavioral Sciences, Tulane University, New Orleans, Louisiana.|Escuela Profesional de Ingeniería Física, Facultad de Ciencias, Universidad Nacional de Ingeniería.
Germán
G
Comina
Laboratorio de Investigación en Enfermedades Infecciosas, Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia.|Laboratorio de Bioinformática y Biología Molecular, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú.
Mirko
M
Zimic
Laboratorio de Investigación en Enfermedades Infecciosas, Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia.
Jorge
J
Coronel
Laboratorio de Investigación en Enfermedades Infecciosas, Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia.
Luz
L
Caviedes
Servicio de Neumología, Hospital Nacional Alcides Carrión,Bellavista , Peru.
José L
JL
Cabrera
Servicio de Neumología, Hospital Nacional Dos de Mayo, Lima, Peru.
Antonio
A
Salas
Facultad de Medicina, Univ Nacional Mayor de San Marcosersidad, Lima, Peru.|Servicio de Enfermedades Infecciosas y Tropicales, Hospital Nacional Dos de Mayo, Lima, Perú.
Eduardo
E
Ticona
Department of Internal Medicine, Cleveland Clinic, Ohio, USA.
Nancy M
NM
Vu
Infectious Diseases and Immunity and Wellcome Trust Imperial College Centre for Global Health Research, Imperial College London, United Kingdom.
Daniela E
DE
Kirwan
Infectious Diseases and Immunity and Wellcome Trust Imperial College Centre for Global Health Research, Imperial College London, United Kingdom.
Maria-Cristina I
MI
Loader
Infectious Diseases and Immunity and Wellcome Trust Imperial College Centre for Global Health Research, Imperial College London, United Kingdom.
Jon S
JS
Friedland
Laboratorio de Investigación en Enfermedades Infecciosas, Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia.|Asociación Benéfica PRISMA, Lima, Perú.|Tuberculosis Centre, London School of Hygiene and Tropical Medicine, United Kingdom.
David A J
DAJ
Moore
Asociación Benéfica PRISMA, Lima, Perú.|Innovation For Health And Development, Laboratory of Research and Development,Universidad Peruana Cayetano Heredia, Lima, Peru.|Infectious Diseases and Immunity and Wellcome Trust Imperial College Centre for Global Health Research, Imperial College London, United Kingdom.
Carlton A
CA
Evans
Department of Electrical and Computer Engineering, Tufts University, Medford, Massachusetts, USA.
Brian H
BH
Tracey
Laboratorio de Investigación en Enfermedades Infecciosas, Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia.|Asociación Benéfica PRISMA, Lima, Perú.|Program in Global Disease Epidemiology and Control, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, USA.
Robert H
RH
Gilman
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000627:therapeutic use*; D002940:Circadian Rhythm; D003371:Cough / Q000473:pathology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000473:pathology*; D055815:Young Adult
D000995:Antitubercular Agents
airborne transmission; cough; infectiousness; tuberculosis; Peru