Transitional change in the clinical features of pulmonary tuberculosis

An aging population, increased use of immunosuppressive therapy and an increase in patients with risk factors for tuberculosis have induced changes in the clinical features of pulmonary tuberculosis in Japan.

To investigate transitional changes in the clinical features of recent patients with pulmonary tuberculosis.

This study analyzed 820 patients with pulmonary tuberculosis who were culture positive for Mycobacterium tuberculosis in the Kawasaki Medical School Hospital and ten associated community hospitals between January 1986 and December 2005 (406 patients between January 1986 and December 1995 and 414 patients between January 1996 and December 2005).

The characteristic clinical features of the latter period were as follows: (1) an increase in the percentages of patients with both malignant diseases and collagen vascular diseases, (2) a decrease in the proportion of patients with obvious clinical symptoms, (3) an increase in the number of microbiologically smear-positive patients, (4) an increase in the percentages of patients with atypical radiological findings, (5) no change in the incidence of multidrug-resistant M. tuberculosis and (6) no change in the rate of the effect of treatment or prognosis.

The findings of an increase in atypical features may be related to the increase in immunocompromised patients and should therefore be investigated further. Performance of acid-fast bacillus examination is extremely important because a good prognosis can be achieved if an accurate diagnosis is established as soon as possible and the resistance of M. tuberculosis to antituberculous drugs has not progressed.