Pulmonary tuberculosis among patients hospitalised with community-acquired pneumonia in a tuberculosis-prevalent area

Abstract

Setting: A suburban teaching hospital in a tuberculosis (TB) prevalent area.

Objectives: To evaluate the proportion of pulmonary TB among patients hospitalised with suspected community-acquired pneumonia (CAP), and to develop a diagnostic index for identifying TB among these patients.

Design: TB cases confirmed using 1) sputum culture, or 2) both sputum acid-fast bacilli smear and polymerase chain reaction for Mycobacterium tuberculosis, were compared with non-tuberculous CAP by demographic, clinical, laboratory and radiographic information. Using multiple logistic regression analysis, risk factors for TB were identified. A diagnostic index was developed by summing up their simplified regression coefficients. Its performance was checked using c-statistic.

Results: TB was the second leading cause of CAP (37/528, 7.0%). Risk factors were initial symptoms >7 days, serum albumin <3.5 g/dl, cavitary/nodular infiltrates and upper lobe involvement (1 point for each). The c-statistic of the index was 0.856 (95%CI 0.789-0.923), and for bootstrapping samples of 1000 repetitions it was 0.856 (95%CI 0.791-0.921). For scores ≥2, sensitivity and specificity were respectively 81.1% and 75.8%.

Conclusion: TB is one of the leading causes of CAP in TB-prevalent areas. Our diagnostic index may help clinicians identify TB immediately from CAP and initiate appropriate isolation and optimal treatment.