Background:
Cough frequency, and its duration, is a lab-free bio
marker that can be used in
low-resource settings and has been associated with transmission and treatment response.
Radiological characteristics associated with increased cough frequency
may be important
in
understanding transmission. The relationship between cough frequency and cavitary lung
disease has never been studied.
Methods:
We analyzed 41 human immunodeficiency virus-negative adults with culture-
confirmed, drug-susceptible pulmonary tuberculosis 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 time to positivity. Computerized tomography scans were
analyzed by a U.S. board-certified radiologist and an automated-computer algorithm. The
algorithm evaluates cavity volume and cavitary proximity to the airway. Computerized
tomography scans were taken within one month of treatment initiation. We compared small
cavities (≤7-mL) versus large cavities (>7-mL) and cavities located closer to (≤10-mm) and
farther (>10-mm) from the airway to cough frequency and cough cessation until treatment
day 62.
Results:
Cough
frequency during treatment was two-fold higher in pa
rticipants with large
cavity volumes (Rate Ratio [RR]=1.98, p=0.01) and
cavities located closer to the airway
(RR=2.44, p=0.001). Comparably, cough ceased three times faster in
smaller cavities (adjusted hazard ratio [HR]=2.89, p=0.06)
and those farther from the airway (adjusted
HR=3.61, p=0.02). Similar results are found for bacillary burden and culture conversion
during treatment.
Conclusions:
Cough frequency
during treatment is greater and
lasts for longer in patients
with larger cavities, especially those closer to the airway