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.

OBJECTIVES

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).

METHODS

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.

RESULTS

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).

DISCUSSION: 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.

CONCLUSION

Biometric identification is useful for assessment of CRT coverage and contamination.

TRIAL REGISTRATION NUMBER: https://clinicaltrials.gov/study/NCT03719521.