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Free Content Yield of serial sputum specimen examinations in the diagnosis of pulmonary tuberculosis: a systematic review [Review Article]

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Current international tuberculosis (TB) guidelines recommend the microscopic examination of three sputum specimens for acid-fast bacilli in the evaluation of persons suspected of having pulmonary TB. We conducted a systematic review of studies that quantified the diagnostic yield of each of three sputum specimens. By searching multiple databases and sources, we identified a total of 37 eligible studies. The incremental yield in smear-positive results (in studies using all smear-positive cases as the denominator) and the increase in sensitivity (in studies that used all culture-positive cases as the denominator) of the third specimen were the main outcomes of interest. Although heterogeneity in study methods and results presented challenges for data synthesis, subgroup analyses suggest that the average incremental yield and/or the increase in sensitivity of examining a third specimen ranged between 2% and 5%. Reducing the recommended number of specimens examined from three to two (particularly to two specimens collected on the same day) could benefit TB control programs, and potentially increase case detection for several reasons. A number of operational research issues need to be addressed. Studies examining the most effective and efficient means to utilize current technologies for microscopic examination of sputum would be most useful if they followed an internationally coordinated and standardized approach, both to strengthen the country-specific evidence base and to permit comparison among studies.

Keywords: acid-fast bacillus; incremental yield; serial sputum specimens; smear microscopy; tuberculosis

Document Type: Review Article

Affiliations: 1: United Nations Children's Fund/United Nations Development Programme/World Bank/World Health Organization (WHO) Special Programme for Research and Training in Tropical Diseases (TDR), WHO, Geneva, Switzerland 2: Albany Medical College, Albany, New York, USA 3: County of Sacramento Department of Health and Human Services, Sacramento, California, USA 4: WHO Tuberculosis Laboratory Consultants Group, Schoemberg, Germany 5: Foundation for Innovative New Diagnostics (FIND), Geneva, Switzerland 6: Stop TB Department, WHO, Geneva, Switzerland 7: Department of Epidemiology & Biostatistics, McGill University, Montreal, Quebec, Canada

Publication date: May 1, 2007

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  • The International Journal of Tuberculosis and Lung Disease publishes articles on all aspects of lung health, including public health-related issues such as training programmes, cost-benefit analysis, legislation, epidemiology, intervention studies and health systems research. The IJTLD is dedicated to the continuing education of physicians and health personnel and the dissemination of information on tuberculosis and lung health world-wide.

    Certain IJTLD articles are selected for translation into French, Spanish, Chinese or Russian. They are available on the Union website

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