Quality of sputum smear microscopy in Taiwan

Background and Purpose: Four mycobacteriology laboratories in northern Taiwan collected slides from their routine work for an international training course on quality assurance of sputum smear microscopy held from 19-27 August 2004 in Taipei. Rechecking of a random sample of these slides provided an opportunity to evaluate the quality of sputum smear microscopy in the collaborating laboratories. Methods: Participants used a systematic sampling method to choose 100 to 120 slides from a set of 600 to 800 slides for evaluating the quality of smear and rechecking. Recheckers were blinded to the microscopy results reported by the testing laboratories. Discordant slides were re-examined by a second rechecker in order to make the final decision. Results: A total of 433 slides were evaluated for smear quality. Of these 433 slides, 177 (41%) had proper smear size, 194 (45%) proper thickness and 212 (49%) proper staining. Rechecking of slides revealed that 2 of 4 laboratories had at least 1 high false-negative and 3 of 4 laboratories had at least 1 low false-negative result. Conclusions: We conclude that: 1) the 2 laboratories with high false-negative results need a supervisory visit in order to determine the causes; and 2) the national tuberculosis program should direct more attention to the quality of sputum smear microscopy and develop a formal plan for external quality assessment of sputum smear microscopy in Taiwan.