[Clinical evaluation of inpatients with tuberculosis diagnosed after admission--comparison of characteristics of patients diagnosed with and without the acid-fast bacillus test].

PURPOSE To evaluate the clinical characteristics of patients in whom tuberculosis was not suspected before admission but was diagnosed after admission. METHODS We enrolled 39 inpatients who were diagnosed with tuberculosis between April 2007 and March 2011 at Jichi Medical University Hospital. The patients were divided into 2 groups as follows: those who underwent a preadmission acid-fast bacillus (AFB) test (AFB group) and those who did not (non-AFB group). We retrospectively evaluated the clinical characteristics of these 2 groups of patients. RESULTS A total of 22 patients and 17 patients comprised the non-AFB and AFB groups, respectively. The prevalence rates of malignancy (9 vs. 2 patients, p = 0.04), extrapulmonary tuberculosis without pulmonary tuberculosis (9 vs. 2 patients, p = 0.04), and smear-negative tuberculosis (16 vs. 7 patients, p = 0.04) were higher in the non-AFB group than in the AFB group. In contrast, the computed tomographic findings of the patients with pulmonary tuberculosis revealed that compared with the AFB group, the non-AFB group had less consolidation (2 vs. 11 patients, p < 0.01) and fewer cavitary lesions (0 vs. 6 patients, p < 0.01) and more nodular lesions (8 vs. 2 patients, p < 0.01). We then divided the inpatients into groups with and without malignancy and compared their clinical characteristics. The mean interval from admission to diagnosis of tuberculosis was significantly longer in the patients with malignancy as an underlying disease than in those without malignancy (23.5 vs. 10.5 days; p < 0.01). CONCLUSION Malignancy was the most frequent underlying disease in the tuberculosis inpatients in the non-AFB group and could be the reason for the delayed diagnosis of tuberculosis.