Impact of active case-finding for tuberculosis on case-notifications in Blantyre, Malawi: A community-based cluster-randomised trial (SCALE)

Feasey, H. R.A. et al. (2023) Impact of active case-finding for tuberculosis on case-notifications in Blantyre, Malawi: A community-based cluster-randomised trial (SCALE). PLoS Global Public Health, 3(12), e0002683. (doi: 10.1371/journal.pgph.0002683) (PMID:38051717) (PMCID:PMC10697577)

Abstract

Active case-finding (ACF) for tuberculosis can help find the “missing millions” with undiagnosed tuberculosis. In a cluster-randomised trial, we investigated impact of ACF on case-notifications in Blantyre, Malawi, where ACF has been intensively implemented following 2014 estimates of ~1,000 per 100,000 adults with undiagnosed TB. Following a pre-intervention prevalence survey (May 2019 to March 2020), constrained randomisation allocated neighbourhoods to either door-to-door ACF (sputum microscopy for reported cough >2 weeks) or standard-of-care (SOC). Implementation was interrupted by COVID-19. Cluster-level bacteriologically-confirmed case-notification rate (CNR) ratio within 91 days of ACF was our redefined primary outcome; comparison between arms used Poisson regression with random effects. Secondary outcomes were 91-day CNR ratios comparing all tuberculosis registrations and all non-ACF registrations. Interrupted time series (ITS) analysis of CNRs in the SOC arm examined prevalence survey impact. (ISRCTN11400592). 72 clusters served by 10 study-supported tuberculosis registration centres were randomised to ACF (261,244 adults, 58,944 person-years follow-up) or SOC (256,713 adults, 52,805 person-years). Of 1,192 ACF participants, 13 (1.09%) were smear-positive. Within 91 days, 113 (42 bacteriologically-confirmed) and 108 (33 bacteriologically-confirmed) tuberculosis patients were identified as ACF or SOC cluster residents, respectively. There was no difference by arm, with adjusted 91-day CNR ratios 1.12 (95% CI: 0.61–2.07) for bacteriologically-confirmed tuberculosis; 0.93 (95% CI: 0.68–1.28) for all tuberculosis registrations; and 0.86 (95%CI: 0.63–1.16) for non-ACF (routinely) diagnosed. Of 7,905 ACF and 7,992 SOC pre-intervention survey participants, 12 (0.15%) and 17 (0.21%), respectively, had culture/Xpert-confirmed tuberculosis. ITS analysis showed no survey impact on SOC CNRs. Despite residual undiagnosed tuberculosis of 150 per 100,000 population, there was no increase in tuberculosis notifications from this previously successful approach targeting symptomatic disease, likely due to previous TB ACF and rapid declines in TB burden. In such settings, future ACF should focus on targeted outreach and demand creation, alongside optimised facility-based screening.

• Item Type: Articles
• Additional Information: Funding: This work was funded through ELC's Wellcome fellowship 200901/Z/16/Z. PM was also supported through a Wellcome fellowship: 206575/Z/17/Z.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Nliwasa, Dr Marriott and MacPherson, Professor Peter

Creator Roles

MacPherson, P.: Formal analysis, Methodology, Supervision, Writing – review and editing
Nliwasa, M.: Resources, Writing – review and editing

• Authors: Feasey, H. R.A., Khundi, M., Nzawa Soko, R., Bottomley, C., Chiume, L., Burchett, H. E.D., Nliwasa, M., Twabi, H. H., Mpunga, J. A., MacPherson, P., and Corbett, E. L.
• College/School: College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > General Practice and Primary Care; College of Medical Veterinary and Life Sciences > School of Health & Wellbeing > Public Health
• Journal Name: PLoS Global Public Health
• Publisher: Public Library of Science
• ISSN: 2767-3375
• ISSN (Online): 2767-3375
• Copyright Holders: Copyright: © 2023 Feasey et al.
• First Published: First published in PLoS Global Public Health 3(12): e0002683
• Publisher Policy: Reproduced under a Creative Commons licence
• Data DOI: 10.17605/OSF.IO/FVQTW