A method to determine the utility of the third diagnostic and the second follow-up sputum smear examinations to diagnose tuberculosis cases and failures
OBJECTIVE: To determine the number of sputum smear examinations required to identify one additional case of tuberculosis from a third serial diagnostic smear or one additional treatment failure from a second serial follow-up smear.
MATERIAL AND METHODS: Country-specific prevalence of new cases and failures among 59665 examinees were determined, as well as the incremental yield from serial smears. The reciprocal value of the product of the prevalence of cases or failures and the respective incremental yield from the last serial smear provided the number of slides that have to be examined to identify one additional case or failure.
RESULTS: The expected prevalence of cases among suspects ranged from 5.4% to 32.8%; the incremental yield from a third serial smear ranged from 0.7% to 7.2%. Between 122.7 and 796.3 smears were required to identify one additional case with the third serial smear. The prevalence of failures among follow-up examinees ranged from 1.0% to 2.5%; the incremental yield from the second follow-up serial smear ranged from 4.5% to 26.9%. Between 164.8 and 2133.4 slides were required to identify one additional failure with the second serial smear.
CONCLUSION: The utility of serial smears can be rationally determined by careful review of program data.
Document Type: Regular Paper
Affiliations: Tuberculosis Division, International Union Against Tuberculosis and Lung Disease, Paris, France
Publication date: 2005-04-01
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.
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