Implementation and impact of a 5-year community-based tuberculosis screening intervention in Cambodia: a mixed-methods pragmatic evaluation using the RE-AIM framework

Background: Cambodia is a high-TB burden country where over a third of TB cases have gone undetected. The Community Mobilisation Initiatives to End TB (COMMIT) programme, implemented across four provinces and 27 operational districts (ODs) in Cambodia from October 2019 to September 2024, aimed to improve TB case finding, diagnosis, treatment, and prevention through community-driven approaches. This study evaluated the implementation, programme outcomes, and sustainability of COMMIT to inform future TB initiatives. Methods: This mixed-methods explanatory sequential study used the Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) framework. Quantitative data were collected from the programme database and the national TB Management Information System (TB-MIS). In-depth interviews, guided by the Theoretical Domains Framework (TDF), explored contextual factors influencing programme implementation and complement quantitative findings. Quantitative data were analysed descriptively to estimate screening coverage, diagnostic yield, and construct care cascades. Qualitative data were transcribed and translated into English, coded, consolidated into a matrix structured using RE-AIM and TDF components, and analysed thematically. Results: COMMIT screened 695,970 people for TB. Key populations were reached, though sex and age disparities in screening participation reflected underlying social and structural barriers. Approximately 98% of those screened underwent diagnostic testing. Treatment initiation (>99%) and completion (>97%) rates were high. COMMIT operationalised contact investigation and evaluation for TB preventive treatment (TPT), screening over 90% of notified contacts. More than 20,000 people were TPT-eligible, of whom 68.7% enrolled in and 86.2% completed TPT. These programme outcomes were supported by strong community engagement, expansion of rapid molecular diagnostics, and programme adaptability during COVID-19. COMMIT was scaled from 10 to 27 ODs, during which it strengthened community capacity by training healthcare workers and expanding peer support groups. Stakeholders emphasised the need to reinforce local ownership and public-private sector collaboration, strengthen integrated services, and de-implement low-value practices such as symptom-based screening. Conclusions: COMMIT improved TB case detection, treatment support, and prevention in Cambodia through community-led strategies and sustained capacity building. Maintaining the programme impact will require continued investment in community systems, de-implementation of low-value practices, and the adoption of efficient, person-centred approaches that address evolving community needs.