Data from: Dynamics of cough frequency in adults undergoing treatment for pulmonary tuberculosis

Background: 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. Methods: We prospectively evaluated HIV-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. Results: The highest cough
frequency occurred from 1-2 p.m., and the lowest from 1-2 a.m. (2.4 versus
1.1 cough episodes/hour, respectively). Cough frequency was higher among
participants who had higher sputum bacillary load (p<0.01).
Pre-treatment median cough episodes/hour was 2.3 (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<0.001. By
14 treatment days, the probability of culture conversion was 29% (95%
CI=19-41%). Conclusions: Coughs were most frequent during daytime. Two
weeks of appropriate treatment significantly reduced cough frequency and
made one-third of participants achieve culture conversion. Thus treatment
by two weeks considerably diminishes but not eliminates the potential for
airborne tuberculosis transmission.