Pulmonary Tuberculosis in the Elderly mae Hospital during the period January 1994 to December 2000, were reviewed. We included only pulmonary TB cases and excluded all other forms of TB, like hilar and/or medi- astinal lymphadenopathy, TB pleurisy, and miliary TB to allow better data comparisons. Cases of pulmonary TB with coexistent extrapulmonary TB were also excluded from the study population. During the study period, 428 cases of active pulmonary TB were treated using anti-TB medication. Thir- ty-five relapsed cases, 20 multi-drug resistant TB cases, and 47 cases already diagnosed as TB at other hospital were also excluded. Finally 326 patients that satisfied the above crite- ria were eligible for analysis. For comparison purposes, the 326 pulmonary TB patients were divided into two groups: patients aged less than 65 yr (the young patients) and those aged 65 yr or more (the elderly patients). All patients were human immunodeficiency virus (HIV) negative. Diagnosis of active pulmonary tuberculosis Sputum acid-fast bacilli (AFB) smear/cultures were per- formed at least three times. Bronchoscopy and washing for AFB detection was performed only in selected patients; only 14 young and 15 elderly underwent bronchoscopy procedure. Active pulmonary TB was diagnosed in the presence of at least one of the following criteria; 1) a positive sputum or bronchial washing fluid AFB smear and/or positive culture for M. tuberculosis regardless of sputum or bronchial wash- ing fluid smear results; 2) biopsy-based histologic confirma- tion of the lung lesion; 3) chest radiographic findings com- patible with TB and a favorable response to treatment in cases without bacteriologic or histologic confirmation. Data collection Collected data included the following: demographic charac- teristics, presenting symptoms and body temperature, under- lying illnesses, laboratory findings (including microbiologic study at the time of diagnosis), radiological features, adverse reaction to anti-TB drugs, and mortality during treatment. Initial presenting symptoms about which patients complained, and highest body temperature measured during initial pre- sentation were included. A body axillary temperature above 37.5℃ was defined as elevated. The location, lesion appear- ance on initial chest radiographs, and first clinical diagnoses were recorded. TB lesion locations were categorized as upper lobe involvement (upper alone or upper with middle or lower) and isolated middle or lower lobe involvement. The radio- logic appearances of TB lesions were classified as typical fibrous nodular and/or a cavitary lesion, a pneumonia-like lesion, a mass-like lesion, or as others. This radiologic classification was made according to interpretation of initial radiographs taken when patients first visited hospital before a definite diagnosis had been made. First clinical diagnoses were clas- sified as TB, bacterial pneumonia, lung cancer, and others. 785 After a diagnosis of active pulmonary TB had been made and medication started, all patients were seen one week after medi- cation start by a physician and monthly thereafter, and at these visits were questioned about drug side effects. Liver function tests were checked after one week of medication, and were monitored by complete blood count (CBC) and simple chest radiography monthly thereafter. Anti-tuberculosis medication Patients were treated initially using the following daily regimen: isoniazid 400 mg (300 mg for patients with a body weight <50 kg), rifampicin 600 mg (450 mg for patients with a body weight <50 kg ), ethambutol 800mg (600 mg for those with a body weight <50 kg), pyrazinamide 1,500 mg (1,000 mg for those with a body weight <50 kg). Pyrazi- namide was medicated through the entire treatment period if patients were tolerable and no adverse reaction occurred. In patients with underlying liver disease, e.g., liver cirrhosis or active hepatitis, pyrazinamide was not prescribed from the medication regimen from the start. Non-hepatotoxic drugs like cycloserine or quinolones were prescribed in patients with significant hepatotoxicity (serum transaminase >3 times the normal upper limit). But as soon as liver function recovered or stabilized, drug therapy regimens were cautiously changed to regimens that included isoniazid and rifampin. Treatment duration was at least 6 months. Adverse drug reactions Drug adverse reactions were defined as; 1) side effects that caused medication discontinuance or change (either tempo- rally or permanently) and/or that directly resulted in hospi- talization; or 2) when some other symptomatic treatment was necessary to relieve symptoms. Drug induced hepatitis by anti-TB medication was defined as; 1) a transaminase increase to >3 times the normal upper limit; and 2) any elevation of transaminase above basal levels in the presence of icteric hep- atitis. If drug induced hepatitis was suspected then isoniazid, rifampicin, and pyrazinamide were stopped, but when liver function returned to normal the drugs were sequentially rein- troduced. Pyrazinamide was not reintroduced. Mild side effects tolerated by patients, or transient mild leucopenia (>3,000/ L) were not considered major drug side effects. Prognosis dur- ing treatment was evaluated by mortality during treatment. Statistics Statistical analysis was performed using the SPSS Version 11.0 software package. Statistical differences between the clini- cal features of the two groups were determined with chi-square test and Yates correction except when expected values of less than 5 required the use of the Fisher exact test. The Student’s t test was used when indicated for independent means.