788 et al. (15) also reported similar results, though they found that hemoptysis occurred equally in both groups. However, Umeki (8) reported that weight loss is more prevalent in elderly patients, and that more specific pulmonary symptoms such as hemoptysis and sputum, occur equally in both groups. Differences in symptom frequencies between Umeki’s study and the present study may be explained by earlier pulmonary TB detection by mass survey in the former study. Several factors may predispose the reactivation of dormant lesions in TB. These include insulin-dependent diabetes mel- litus, poor nutrition, long-term corticosteroid therapy, other debilitating diseases, smoking, alcohol abuse, and waning cell- mediated immunity (4). Our study also supported the role of a reduced immune function in the development of pulmonary TB both in the young and elderly. A considerable number of patients in both groups had underlying disease, though the elderly were found to be more likely to have underlying disease. Diabetes mellitus and liver disease were the major underlying illness in both groups in the present study. In par- ticular, the elderly had significantly higher frequencies of car- diovascular and chronic lung diseases, including pneumoco- niosis, whereas the young had a significantly higher frequency of liver disease, suggesting the influence of alcoholism. These results correspond to those of Alvarez et al. (6) and Van den Brande (15) but contrast with those of Katz et al. (17) and Umeki (8), who found that malignancies and immunosup- pressive drug intakes were higher in the elderly. This differ- ence between studies may be due to a higher prevalence of TB in Korea. There had been much debate concerning the atypical radio- graphic findings of TB in the elderly. Some have reported no major differences in radiologic features (18, 19), while others have reported a higher involvement of the middle and lower lung fields in the elderly (8, 9), whereas the present study shows significantly higher frequencies of isolated mid- and lower lung involvements in the elderly. The radiographic appearances were also different in these two age groups. Our findings are consistent with those of Perez (10) and Chan (11) in this respect. Our results highlight the importance of sputum AFB smear/ culture for the diagnosis of TB in the elderly. A positive spu- tum AFB smear was obtained in 57.1% of elderly and in 57.5 % of young TB patients, and a positive AFB culture was ob- tained in 70.6% of the elderly and in 74.4% of the young, neither of which was significantly different. Moreover, these results compare well with other reports (7, 18, 21). Although Morris (22) previously suggested that AFB smears are not sensitive enough to diagnose non-cavitating tuberculosis in the elderly, many studies have reported that sputum AFB tests are powerful tools for the diagnosis of pulmonary TB in the elderly (4, 23). In a study by Mackay and Cole (24), sputum AFB smears yielded positive results in 45% patients with pulmonary TB, and sputum cultures were positive in 53% of elderly patients. Dahmash et al. (21) reported the J.H. Lee, D.H. Han, J.W. Song, et al. detection of AFB in expectorated sputum specimens in 62.5% of patients. The reason for the somewhat higher sputum AFB detection rate of the present study is presumed to be due to patient population bias. Our hospital is a municipal hospital and many patients frequently visit physicians after the disease has progressed to an advanced stage due to a poor socioeco- nomic status. Thus in the present study, there is a possibility that the higher sputum AFB detection rate reflected a more advanced disease stage. The low incidence of asymptomatic patients in our study population supports this possibility. Recently, Patel et al. (25) reported the usefulness of fiberop- tic bronchoscopy in the diagnosis of TB. Fiberoptic broncho- scopy may be helpful in some elderly patients who are sus- pected of having TB, but who cannot expectorate adequate sputum. In the present study, only selected patients received a bronchoscopic examination, and a more aggressive broncho- scopic examination may well have revealed an advantage. The appearance of adverse drug reactions is important when determining the effectiveness of anti-TB therapy. It has been suggested that adverse reactions to anti-TB drugs are more likely in the elderly (12, 13, 26). In the present study, the elderly did not tolerate drugs as well as the young, and expe- rienced higher frequencies of adverse reactions. The most fre- quent side effects were drug-induced hepatitis and skin side effects. The incidence of reported anti-TB drug-induced hep- atitis has been reported to show wide variations, which appear to be dependent on the definition of hepatotoxicity used (27- 29). However, the majority of studies show that the elderly are more susceptible to anti-TB drug induced hepatotoxicity (12, 13). Using a similar definition to that used in the pre- sent study (i.e., serum transaminase >3×the normal upper limit), Fernandez-Villar et al. (30) found an 18.2% incidence of hepatotoxicity in the risk factor group (advanced age, chronic liver disease, abuse of alcohol, and others), and van den Brande et al. (31) a 22% incidence of hepatotoxicity (transaminase increase >5 times the basal level) in elderly TB patients. Sharma et al. (29) also reported a 16.2% drug-induced hepa- totoxicity level in the elderly. Recently Yee et al. (13) report- ed that serious drug side effects, especially hepatitis and rash, is highest for pyrazinamide, and that this is associated with a female sex, an older age, birth in Asia, and HIV infection. Though we now discontinue pyrazinamide after 2 month of anti-TB medication, pyrazinamide was prescribed during the study period if it was tolerated for the entire treatment period due to the fear of drug resistance. This may partly explain the somewhat high incidence of drug-induced hepatitis observed in the present study. Several have reported (6, 14, 24) higher TB related mor- talities in elderly patients. In the present study, all young pul- monary TB patients survived except two, whereas 9 (11.1%) of the elderly patients died of TB. Some have even reported mortality rates as high as 20 to 40% in elderly TB patients (21). In the present study, differences in mortality might be partly explained by the exclusion of miliary TB. Our results