Frequency of tuberculosis in anthracosis of the lung: a systematic review.

INTRODUCTION Anthracosis of the lung is the blackening of bronchial tissues which can lead to chronic bronchial obstruction. Many studies have shown association of bronchial anthracosis and tuberculosis. The aim of this study was accumulation of scattered studies and getting the definite conclusion about the association between anthracosis and tuberculosis. MATHERIALS AND METHODS We conducted a systematic search that included studies with sufficient information about the frequency of tuberculosis in anthracosis (anthracofibrosis) patients and non-anthracotic control group. Moreover, tuberculosis should be confirmed by microbiologic (smear or culture) or histopathological methods. RESULTS Twelve studies (eight studies on anthracofibrosis and four studies on anthracosis as a general term) comprising of 6280 patients was entered into our meta-analysis. The frequency of tuberculosis in all anthracosis patients was 22.5 % (32.3 % for anthracofibrosis and 16.6 % for anthracosis), which was significantly higher than the control group. Determination of risk showed that the cumulated odds ratio of tuberculosis in all studies of anthracosis was 3.16 (95 % CI = 2.49 - 6.85), which revealed significantly higher risk than the control group. The analysis of the subgroups showed that the cumulated odds ratio of tuberculosis in subgroups of anthracofibrosis (3.28; 95 % CI = 2.16 - 9.12) was significantly higher than anthracosis as a general term (2.85; 95 % CI = 1.73 - 6.61). DISCUSSION The association of tuberculosis with all types of anthracosis of the lung was confirmed and a proper mechanism should be defined.