EP03-120-21 Disease patterns on computer-assisted chest radiography in a community-based prevalence survey for tuberculosis

Background: Tuberculosis (TB) is one of the leading causes of death from a single infectious disease agent. Better screening and testing approaches are needed to improve TB screening and case finding. There is a growing interest in the automated analysis of chest x-rays as a sensitive and inexpensive means of screening popula- tions for pulmonary TB.

Design/Methods: The SCALE study (Sustainable Com- munity-wide Active Case Finding for Lung hEalth) is a cluster randomised trial investigating whether providing periodic TB/HIV active case finding leads to reduced prevalence of undetected adult infectious TB disease in Blantyre, Malawi. During the trial prevalence survey, participants were screened for TB using sputum for microscopy and Xpert MTB/RIF, as well as computer- assisted digital chest radiography (CAD-DCXR), and referred to a community-based clinic for evaluation if they had an abnormal x-ray based on radiographer assessment. We estimated prevalence of CXR abnormali- ties, described using the WHO Integrated Management for Adult Illnesses classification (IMAI), and how they related to CAD-DCXR interpretation.

Results: We screened 13,915 participants. 650 had abnormal CXRs and were referred to the clinic. 382 (58.8%) participants attended the community-based clinic. 92 (24.1%) were HIV positive, 92% of whom were on ART. 1 in 5 people were found to have hypertension, with 80% of them having an abnormal CXR. 21 (5.5%) were iden- tified as active TB disease and were linked to health fa- cilities for repeat microbiological testing and treatment initiation. The commonest causes of CXR abnormality was cardiomegaly (n = 83 [21.7%]). The CAD-DCXR system described 61 (16%) to have abnormalities consistent with active TB, 34 (8.9%) having cardiomegaly and 47 (12.3%) having non-classifiable abnormalities.

Conclusions: This evaluation draws a broad picture of the burden of disease at community level in Blantyre, which consists of a large burden of undiagnosed non- communicable diseases, and the role of computer-assisted radiography in community-based disease screening.