Predicting Mycobacterium tuberculosis in patients with community-acquired pneumonia

The 22 risk factors suggested by the Centers for Disease Control and Prevention (CDC) to predict patients at risk for Mycobacterium tuberculosis have not been evaluated in hospitalised patients with community-acquired pneumonia (CAP). We evaluated which of the CDC risk factors best predict M. tuberculosis in these patients. To our knowledge, this is the first time a score has been developed assessing these risk factors. This was a secondary analysis of 6976 patients hospitalised with CAP enrolled in the Community-Acquired Pneumonia Organization International Cohort Study. Using Poisson regression, we selected the subset of risk factors that best predicted the presence of CAP due to M. tuberculosis. This subset was compared to the CDC risk factors using receiver operating characteristic (ROC) curve analysis. Five risk factors were found to best predict CAP due to M. tuberculosis: night sweats, haemoptysis, weight loss, M. tuberculosis exposure and upper lobe infiltrate. The area under the ROC curve for all CDC risk factors was 71% and 89% for the subset of five risk factors. The CDC-suggested risk factors are poor at predicting the presence of M. tuberculosis in hospitalised patients with CAP. With a subset of five risk factors identified in this study, we developed a new score, which will improve our capacity to isolate patients at risk of CAP due to M. tuberculosis at the time of hospitalisation.