A high-resolution computed tomography-based scoring system to differentiate the most infectious active pulmonary tuberculosis from community-acquired pneumonia in elderly and non-elderly patients.

OBJECTIVE: The objective of this study was to use high-resolution computed tomography (HRCT) imaging to predict the presence of smear-positive active pulmonary tuberculosis (PTB) in elderly (at least 65 years of age) and non-elderly patients (18-65 years of age). METHODS: Patients with active pulmonary infections seen from November 2010 through December 2011 received HRCT chest imaging, sputum smears for acid-fast bacilli and sputum cultures for Mycobacterium tuberculosis. Smear-positive PTB was defined as at least one positive sputum smear and a positive culture for M. tuberculosis. Multivariate logistic regression analyses were performed to determine the HRCT predictors of smear-positive active PTB, and a prediction score was developed on the basis of receiver operating characteristic curve analysis. RESULTS: Of 1,255 patients included, 139 were diagnosed with smear-positive active PTB. According to ROC curve analysis, the sensitivity, specificity, positive predictive value, negative predictive value, false positive rates and false negative rates were 98.6 %, 95.8 %, 78.5 %, 99.8 %, 4.2 % and 1.4 %, respectively, for diagnosing smear-positive active PTB in elderly patients, and 100.0 %, 96.9 %, 76.5 %, 100.0 %, 3.1 % and 0.0 %, respectively, for non-elderly patients. CONCLUSIONS: HRCT can assist in the early diagnosis of the most infectious active PTB, thereby preventing transmission and minimizing unnecessary immediate respiratory isolation. KEY POINTS: • HRCT can assist in the early diagnosis of the infectious active PTB • HRCT imaging is useful to predict the presence of smear-positive active PTB • Predictions from the HRCT imaging are valid even before sputum smear or culture results.

Nontuberculous mycobacterial infection is associated with increased respiratory failure: a nationwide cohort study.

BACKGROUND AND PURPOSE: Population study on relationship between nontuberculous mycobacterial (NTM) infection and respiratory failure (RF) is limited. This study evaluated the RF risk, including acute respiratory failure (ARF), chronic respiratory failure (CRF) and ARF on CRF, in patients with NTM infection in Taiwan. METHODS: We used the National Health Insurance Research Database of Taiwan to identify 3864 newly diagnosed NTM patients (NTM cohort) from 1999 to 2009, and 15456 non-NTM patients (non-NTM cohort), frequency matched by demographic status for comparison. Incidence and hazard of developing RF were measured by the end of 2010. RESULTS: The incidence rate of RF was 4.31-fold higher in the NTM cohort than in the non-NTM cohort (44.0 vs.10.2 per 1000 person-years), with an adjusted hazard ratio (HR) of 3.11 (95% CI: 2.73-3.54). The cumulative proportional incidence of RF was 10% higher in the NTM cohort than in the non-NTM cohort (P<0.0001). The RF risk was much greater within 6 months after the diagnosis of NTM infection with a HR of 7.45 (95% CI = 5.50-10.09). Age-specific comparison showed that the younger NTM patients had a higher HR of RF than the elderly NTM patients (HR: 4.42, 95% CI: 3.28-5.96 vs. HR: 2.52, 95% CI: 2.17-2.92). Comorbidity increased the risk of RF in both cohorts, particularly in those with chronic obstructive pulmonary disease. CONCLUSION: Our study suggests patients with NTM infection are at a high risk of RF. The risk appears much greater soon after patients diagnosed with NTM infection.