Cavity Volume and Proximity to Airway May Affect Tuberculosis Treatment
Individuals with tuberculosis who had large cavity volumes closer to the airway had a cough frequency 2-fold higher than in individuals with smaller cavities.
Individuals diagnosed with tuberculosis with large cavitary lung disease may have a greater cough frequency that lasts for a longer period of time, especially when cavities are closer to the airway, according to a study published in CHEST.
Individuals with large cavity volumes had a cough frequency 2-fold higher than those individuals with smaller cavities (rate ratio [RR], 1.98; 95% CI, 1.17-3.35; P =.01). In addition, individuals with cavities farther away from the airway had a significantly lower cough frequency compared with those with cavities closer to the airway (RR, 0.41; 95% CI, 0.248-0.68; P =.001). When cavity volume and proximity to the airway combined were analyzed during treatment, only proximity to the airway was significant (RR, 0.38; 95% CI, 0.20-0.72; P =.003). During treatment, older age had a stronger trend for cough frequency, and both atelectasis and pleural effusion were associated with a higher cough frequency (RR, 1.89 [95% CI, 1.17-3.08; P =.01] and RR, 1.99 [95% CI, 1.06-3.73; P =.03], respectively).
During treatment, a higher bacillary burden and faster culture growth were associated with larger cavity volumes (mean difference [MD], −2.42; 95% CI, −4.6 to −0.28; P =.03), whereas lower bacillary burden and longer time for culture growth was associated with cavities farther from the airway (MD, 3.26; 95% CI, 1.35-5.2; P =.001). Only proximity to the airway remained statistically significant during treatment when analyzing both cavity volume and proximity (MD, 2.76; 95% CI, 1.01-4.5; P =.002).
Despite being observed to have a cough cessation rate 3 times faster in individuals with smaller cavities compared with larger cavities, the results were not found to be statistically significant (adjusted hazard ratio, 2.89; 95% CI, 0.95-8.8; P =.06). Interestingly, cavities located >10 mm from the airway had a 3 times higher hazard for coughing cessation compared with cavities ≤10 mm (adjusted HR, 3.61; 95% CI, 1.26-10.4; P =.02), with probabilities of 37.3% and 75.0% for those closer and farther from the airway, respectively. Probabilities of culture conversion were 100% and 73.3% for small and large cavities, respectively.
The researchers concluded that there is an association between cough frequency during treatment with both cavitary volume and proximity to the airway. Therefore, because a patient with a large cavity close to the airway is at an increased risk of coughing during treatment, clinicians can identify this individual as being at a higher risk for expelling more Mycobacterium tuberculosis into the environment, and should closely monitor them during treatment.
Proaño A, Bui D, López J, et al; for the Tuberculosis Working Group in Peru. Cough frequency during treatment associated with baseline cavitary volume and proximity to the airway in pulmonary tuberculosis [published online March 17, 2018]. CHEST. doi:10.1016/j.chest.2018.03.006