Active case finding for pulmonary tuberculosis using mobile digital chest radiography: an observational study
Abstract:BACKGROUND: Mobile digital chest radiography (CXR) is used routinely to screen for pulmonary tuberculosis (PTB) in London among homeless populations, persons accessing drug treatment services and prisoners.
OBJECTIVE: 1) To establish the sensitivity and specificity of mobile digital CXR, and 2) to test the hypothesis that actively identified cases have reduced odds of sputum smear positivity vs. those presenting passively to health care services from the same populations.
METHODS: Sensitivity and specificity were calculated using a gold standard comparator of culture-confirmed cases of PTB reported to the national surveillance system within 90 days of screening. Logistic regression was used to determine whether actively detected cases had reduced odds of smear positivity compared to passively detected cases after adjustment for confounding.
RESULTS: The intervention had a sensitivity of 81.8% (95%CI 64.5–93.0) and a specificity of 99.2% (95%CI 99.1–99.3). After adjusting for confounding, there was evidence that cases identified through screening were less likely to be smear-positive than passively identified cases (OR 0.34, 95%CI 0.14–0.85; likelihood ratio test P = 0.022).
CONCLUSION: Digital CXR achieves a high level of sensitivity and specificity in an operational setting; targeted mobile radiographic screening can reduce the risk of onward transmission by identifying cases before they become infectious.
Document Type: Research Article
Affiliations: 1: Find and Treat, University College London Hospitals NHS Foundation Trust, London, UK 2: University College London Centre for Infectious Disease Epidemiology, Department of Infection and Population Health, London, UK 3: University College London Centre for Infectious Disease Epidemiology, Department of Infection and Population Health, London, UK; Respiratory Diseases Department, Health Protection Services, Health Protection Agency, London, UK 4: Centre for Respiratory Medicine, University College London, Royal Free London, NHS Foundation Trust, London, UK 5: Respiratory Diseases Department, Health Protection Services, Health Protection Agency, London, UK
Publication date: November 1, 2012
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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