Implementation fidelity of a blended quality improvement strategy to monitor women’s engagement in Option B+ across five high-volume urban facilities in Lilongwe, Malawi

Abstract Background Monitoring peripartum women’s engagement in Option B+ is essential for preventing vertical HIV transmission but remains suboptimal. Quality improvement (QI) may strengthen monitoring, but its use in Option B+ is underexplored. This study assessed implementation fidelity of Process Mapping and Quality Improvement (PROMAQI), a blended QI strategy, and examined monitoring and six-month retention. Methods This implementation fidelity study was conducted in five high-volume facilities in Lilongwe, Malawi, from August 2021 to March 2022, with a nested pre-post uncontrolled quasi-experimental component. PROMAQI included QI capacity-building, mentorship, peer learning, communication, documentation, and resource support. Fidelity was assessed from QI records using content, frequency, duration, and coverage domains and classified as high (≥ 80%), moderate (50–79%), or low (< 50%). Pre- and post-intervention cohorts were identified from routine records. HIV clinic attendance and missed visits were assessed over six months from first antenatal care visit, summarized for months 1–3 and 4–6 of follow-up, and compared descriptively and using logistic regression adjusted for site and visit. Six-month retention was summarized descriptively. Results Overall fidelity was moderate (62.7%), with high content adherence (81.0%) and moderate frequency (50.0%), duration (50.0%), and coverage (69.7%). Among 692 women (pre: 392; post: 300; median age: 28 years), HIV clinic attendance declined over follow-up in both periods, while missed visits increased less after PROMAQI implementation. Adjusted analyses showed reduced odds of missed visits during months 4–6 of follow-up (OR 0.28; 95% CI 0.17–0.47) and higher odds of HIV clinic attendance (OR range: 2.13–3.47). The proportion with at least one documented HIV clinic visit increased from 64.0% to 72.0% in months 1–3 ( p = 0.022) and from 31.0% to 63.0% in months 4–6 ( p < 0.001). Among women already on ART, ≥ 2 visits increased from 28.0% to 56.0% ( p < 0.001); among newly initiated women, ≥ 4 visits increased from 33.0% to 42.0% ( p = 0.120). Six-month retention increased from 44.0% to 72.0%, while missing outcome data declined from 41.0% to 3.7%. Conclusion PROMAQI achieved moderate fidelity, with strong capacity-building but gaps in communication and activity intensity. Implementation was associated with improved monitoring and higher recorded six-month retention. Findings highlight opportunities to strengthen PROMAQI components in high-volume Option B+ settings.