The role of tuberculosis in COPD

BACKGROUND Influence of tuberculosis (TB) on the natural course of COPD has not been well known. This study was designed to investigate the effects of history of TB on the long-term course of COPD. METHODS Patients hospitalized with COPD exacerbation were consecutively included (n=598). Cases were classified into two categories: those with TB history and those without. Clinical, demographic, and radiological features were meticulously recorded, and patients were followed up for hospitalizations due to exacerbation and for overall mortality. RESULTS A total of 93 patients (15%) had a history of TB. On average, patients with past TB history were 4 years younger than the rest of the patients (P=0.002). Our study revealed that patients with past TB were diagnosed with COPD 4 years earlier and died 5 years earlier as compared to the patients without TB. In addition, in the past TB group, rate of hospital admissions per year was higher compared to the group that lacked TB history (2.46±0.26 vs 1.56±0.88; P=0.001). Past TB group had higher arterial carbon dioxide tension (PaCO2) and lower forced expiratory volume in 1 second (FEV1; P=0.008 and P=0.069, respectively). Median survival was 24 months for patients who had past TB and 36 months for those who had not. Kaplan-Meier analysis revealed that although 3-year survival rate was lower in patients with past TB, it was not statistically significant (P=0.08). Cox regression analysis showed that while factors such as age, PaCO2, hematocrit, body mass index (BMI) and Charlson index affected mortality rates in COPD patients (P<0.05), prior history of TB did not. CONCLUSION Our results showed that a history of TB caused more hospitalizations, reduced respiratory functions and increased PaCO2. It was found that, despite similarity of the overall mortality, COPD diagnosis and death occurred 5 years earlier in patients with past TB. We conclude that history of TB has an important role in the natural course of COPD.