Validation of candidate smear microscopy quality indicators, extracted from tuberculosis laboratory registers
Abstract:SETTING: Kinshasa Province, Democratic Republic of Congo.
OBJECTIVE: To identify and validate register-based indicators of acid-fast bacilli (AFB) microscopy quality.
DESIGN: Selection of laboratories based on reliability and variation in routine smear rechecking results. Calculation of relative sensitivity (RS) compared to recheckers and its correlation coefficient (R) with candidate indicators based on a fully probabilistic analysis incorporating vague prior information using WinBUGS.
RESULTS: The proportion of positive follow-up smears correlated well (median R 0.81, 95% credibility interval [CI] 0.58–0.93), and the proportion of first smear-positive cases fairly (median R 0.70, 95% CI 0.38–0.89) with RS. The proportions of both positive suspect and low positive case smears showed poor correlations (median R 0.27 and −0.22, respectively, with ranges including zero).
CONCLUSIONS: The proportion of positives in follow-up smears is the most promising indicator of AFB smear sensitivity, while the proportion of positive suspects may be more indicative of accessibility and suspect selection. Both can be obtained from simple reports, and should be used for internal and external monitoring and as guidance for supervision. As proportion of low positive suspect smears and consistency within case series are more difficult to interpret, they should be used only on-site by laboratory professionals. All indicators require more research to define their optimal range in various settings.
Document Type: Regular Paper
Affiliations: 1: Mycobacteriology Unit, Institute of Tropical Medicine, Antwerp, Belgium; International Union Against Tuberculosis and Lung Disease, Paris, France 2: Department of Social and Preventive Medicine, University of Bern, Bern, Switzerland 3: Programme National de Lutte contre la Tuberculose, Lingwala, Democratic Republic of Congo 4: Fondation Damien, Gombe, Kinshasa, Democratic Republic of Congo 5: International Union Against Tuberculosis and Lung Disease, Paris, France
Publication date: March 1, 2007
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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