Effectiveness and acceptability of biometrics to evaluate intervention coverage and contamination in a cluster randomised trial of community-based sexual and reproductive health services for youth in Zimbabwe.

Authors

Victoria Simms, Tsitsi Bandason, Ethel Dauya, Chido Dziva Chikwari, Chris Grundy, Mandikudza Tembo, Constancia Mavodza, Owen Mugurungi, Tsitsi Apollo, Riffat Ashrafee, Demetris Demetriou, Anindya Sharma, Richard J Hayes, Katharina Kranzer, Rashida A Ferrand

Published in

BMJ open. Volume 16. Issue 7. Pages e107583. Jul 15, 2026. Epub Jul 15, 2026.

Abstract

Low intervention uptake and contamination can dilute effects of cluster randomised trials (CRTs). We investigated the feasibility of digital fingerprints to assess intervention coverage and contamination in a CRT of community-based sexual and reproductive health services for youth (CHIEDZA).
24 clusters in Zimbabwe were randomly allocated to intervention/control. In intervention clusters, CHIEDZA services were provided in community halls for 30 months. A population-based survey of youth aged 18-24 (700/cluster) was conducted to ascertain impact. Digital fingerprints were collected from service attendees and survey participants, and the datasets were linked to assess intervention coverage at population level in intervention clusters and contamination in control clusters. Multilevel logistic regression estimated the association of hall distance with service uptake.
Between April 2019 and March 2022, 36 991 clients attended the CHIEDZA service and 99.9% used biometric registration. In the survey 13 675/17 682 (77.3%) participants completed biometric registration: 1182 refused, 1235 bypassed and 1590 could not register.CHIEDZA service coverage in the intervention clusters was 23.1% and contamination was 3.7%. Against biometric registration match, self-reported service attendance had 75.3% sensitivity (95% CI 73.1% to 77.5%) and 92.7% specificity (95% CI 92.0% to 93.4%). Odds of CHIEDZA service use reduced by 52% for every 1km distance (OR: 0.48 95% CI 0.44 to 0.54).
Biometric identification was feasible and acceptable in a community setting without time pressure. In population-based surveys additional technological challenges emerged. Biometrics enabled good estimation of intervention coverage and validated self-reported data. Youth community services must overcome distance barriers.
Biometric identification is useful for assessment of CRT coverage and contamination.
https://clinicaltrials.gov/study/NCT03719521.

PMID:
42463203
Bibliographic data and abstract were imported from PubMed on 17 Jul 2026.

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