Assessment of Pulmonary Function in Treated Pulmonary Tuberculosis Patients Using Spirometry

Sir, We present our comment on the excellent study by Anand et al.,[1] which was published in the April–June 2025 issue of your distinguished journal. The authors referred to the spirometry reference intervals (SRIs), which were set by the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines. They found normal patterns, obstructive patterns, restrictive patterns, and mixed ventilatory patterns in 0.64%, 64%, 22%, and 13.3% of patients, respectively, in South India who had post-tuberculosis (PTB) sequelae.[1] They concluded that post-tuberculosis PTB sequelae brought about significant pulmonary dysfunction. Herein, we state an important methodological limitation that might bias the study findings. It is advocated that population-specific SRIs of pulmonary function tests are crucial for interpreting readings obtained for a given community and, interestingly, these SRIs were built for the population in South India in 2023.[2] The authors in the study methodology utilized ATS/ERS standards, which were originally developed for Caucasian populations, to group spirometry readings in the study cohort instead of local reference standards.[2] This could potentially result in an overestimation or underestimation of restrictive/obstructive patterns. As a result, cautious evaluation of the study findings is paramount.