Abstract
SummaryBackgroundActive case-finding among contacts of patients with tuberculosis is a global health priority, but the effects of active versus passive case-finding are poorly characterised. We assessed the contribution of active versus passive case-finding to tuberculosis detection among contacts and compared sex and disease characteristics between contacts diagnosed through these strategies.MethodsIn shanty towns in Callao, Peru, we identified index patients with tuberculosis and followed up contacts aged 15 years or older for tuberculosis. All patients and contacts were offered free programmatic active case-finding entailing sputum smear microscopy and clinical assessment. Additionally, all contacts were offered intensified active case-finding with sputum smear and culture testing monthly for 6 months and then once every 4 years. Passive case-finding at local health facilities was ongoing throughout follow-up.FindingsBetween Oct 23, 2002, and May 26, 2006, we identified 2666 contacts, who were followed up until March 1, 2016. Median follow-up was 10·0 years (IQR 7·5–11·0). 232 (9%) of 2666 contacts were diagnosed with tuberculosis. The 2-year cumulative risk of tuberculosis was 4·6% (95% CI 3·5–5·5), and overall incidence was 0·98 cases (95% CI 0·86–1·10) per 100 person-years. 53 (23%) of 232 contacts with tuberculosis were diagnosed through active case-finding and 179 (77%) were identified through passive case-finding. During the first 6 months of the study, 23 (45%) of 51 contacts were diagnosed through active case-finding and 28 (55%) were identified through passive case-finding. Contacts diagnosed through active versus passive case-finding were more frequently female (36 [68%] of 53 vs 85 [47%] of 179; p=0·009), had a symptom duration of less than 15 days (nine [25%] of 36 vs ten [8%] of 127; p=0·03), and were more likely to be sputum smear-negative (33 [62%] of 53 vs 62 [35%] of 179; p=0·0003).InterpretationAlthough active case-finding made an important contribution to tuberculosis detection among contacts, passive case-finding detected most of the tuberculosis burden. Compared with passive case-finding, active case-finding was equitable, helped to diagnose tuberculosis earlier and usually before a positive result on sputum smear microscopy, and showed a high burden of undetected tuberculosis among women.FundingWellcome Trust, Department for International Development Civil Society Challenge Fund, Joint Global Health Trials consortium, Bill & Melinda Gates Foundation, Imperial College National Institutes of Health Research Biomedical Research Centre, Foundation for Innovative New Diagnostics, Sir Halley Stewart Trust, WHO, TB REACH, and IFHAD: Innovation for Health and Development.
Highlights
Reducing tuberculosis transmission in households and communities entails early diagnosis of people living with tuberculosis followed by rapid initiation of appro priate treatment before tuberculosis becomes sputum smear-positive and more infectious.1 WHO estimates that, in 2017, more than a third of people living with tuberculosis were neither diagnosed, treated, nor reported, representing an enormous barrier to tubercu losis control and elimination.2 In most countries of low and middle income with a high burden of tuberculosis, investigation for tuberculosis usually only starts when people present to health services with symptoms suggestive of pulmonary tuberculosis, termed passive case-finding
Index patients were defined as patients registered to receive treatment in Peruvian Ministry of Health (MINSA)-run health posts who had laboratoryconfirmed pulmonary tuberculosis, which in this setting almost always implied a positive result on sputum smear micros copy
We found a substantial burden of tuberculosis through active case-finding, extending evidence from a clusterrandomised trial that showed the effectiveness of active case-finding among contacts using repeated chest radiography and sputum culture testing for increasing tuberculosis case detection
Summary
Reducing tuberculosis transmission in households and communities entails early diagnosis of people living with tuberculosis followed by rapid initiation of appro priate treatment before tuberculosis becomes sputum smear-positive and more infectious. WHO estimates that, in 2017, more than a third of people living with tuberculosis were neither diagnosed, treated, nor reported, representing an enormous barrier to tubercu losis control and elimination. In most countries of low and middle income with a high burden of tuberculosis, investigation for tuberculosis usually only starts when people present to health services with symptoms suggestive of pulmonary tuberculosis, termed passive case-finding. WHO recommends that contacts of newly diagnosed patients are systematically screened because of their well-established high risk of disease.3,4 This active case-finding among contacts—termed con tact investigation—is inconsistently implemented in settings with a high burden of tuberculosis, and evi dence to inform its optimum delivery is scant.. Analyses of prevalence surveys consolidate these case-notification data and show that overall tuberculosis prevalence is twice as high in men than in women.. Analyses of prevalence surveys consolidate these case-notification data and show that overall tuberculosis prevalence is twice as high in men than in women.6 These data are mostly from southeast Asia, Africa, and the western Pacific, with only two small subnational surveys in relatively isolated indigenous communities from Latin America contributing to the analysis. In Latin America, case notifications are consist ently higher in men and, in 2015, 61% of cases notified in Peru were reported in men. prevalence surveys of indigenous communities from Ecuador and Brazil imply a more equal tuberculosis prevalence by sex
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