title: Factors associated with misdiagnosis of smear-negative tuberculosis: an experience in Taiwan.
abstract: BACKGROUND
  A negative sputum smear from a patient with history, physical examination, and chest x-ray findings suggestive of tuberculosis (TB) presents a diagnostic dilemma. We investigated the possible factors associated with a misdiagnosis and inappropriate treatment of TB among  such patients.
  
  
  METHODS
  We reviewed the records of 193 patients whose diagnoses with TB included conflicting test results and were reported to the Taiwan Centers for Disease Control in 2004. When other conditions were found to underlie the initial abnormal chest x-ray finding, the diagnosis  was revised.
  
  
  RESULTS
  Mycobacterium tuberculosis was isolated from sputum samples in 72 of 193 patients (37%), nontuberculous mycobacteria from 4 (2%), and no bacteriologic evidence of M. tuberculosis from 117 (61%). The initial diagnosis of TB was revised for 26 (13.5%) patients.  Patients with positive M. tuberculosis culture had a lower incidence of revised diagnoses (4.2%, P < .001) than those negative for mycobacterial culture (17.1%) and those with nontuberculous mycobacteria (75%). Chest cavitations in this study were not a significant predictor  of revised diagnosis (odds ratio 0.30, P = .08).
  
  
  CONCLUSIONS
  An incorrect diagnosis of TB despite a negative sputum smear result is more likely to be made for patients positive for nontuberculous mycobacteria culture and less likely for patients with positive M. tuberculosis  culture.
authors.affiliation: Department of Internal Medicine, Yongkang Veterans Hospital, and the Department of Occupational Safety and Health, Chia Nan University of Pharmacy and Science, Tainan, Taiwan.
authors.forename: Chih-Yun
authors.initials: CY
authors.lastname: Yang
authors.forename: How-Ran
authors.initials: HR
authors.lastname: Guo
authors.forename: Ya-Yun
authors.initials: YY
authors.lastname: Cheng
authors.forename: Ruay-Ming
authors.initials: RM
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000627:therapeutic use; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis; D012189:Retrospective Studies; D012307:Risk Factors; D013183:Sputum / Q000382:microbiology*; D013624:Taiwan; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis* / Q000188:drug therapy
chemical_list: D000995:Antitubercular Agents