Abstract
INTRODUCTION: Relatively few studies rigorously examine the factors associated with health systems strengthening and scaling of interventions at subnational government levels. We aim to examine how The Challenge Initiative (TCI) coaches subnational (state government) actors to scale proven family planning and adolescent and youth sexual and reproductive health approaches rapidly and sustainably through public health systems to respond to unmet need among the urban poor. METHODS: This mixed-methods comparative case study draws on 32 semistructured interviews with subnational government leaders and managers, nongovernmental organization leaders, and TCI Nigeria staff, triangulated with project records and government health management information system (HMIS) data. Adapting the Consolidated Framework for Implementation Research (CFIR), we contrast experience across 2 higher-performing states and 1 lower-performing state (identified through HMIS data and selected health systems strengthening criteria from 13 states) to identify modifiable factors linked with successful adoption and implementation of interventions and note lessons for supporting scale-up. RESULTS: Informants reported that several TCI strategies overlapping with CFIR were critical to states' successful adoption and sustainment of interventions, most prominently external champions' contributions and strengthened state planning and coordination, especially in higher-performing states. Government stakeholders institutionalized new interventions through their annual operational plans. Higher-performing states incorporated mutually reinforcing interventions (including service delivery, demand generation, and advocacy). Although informants generally expressed confidence that newly introduced service delivery interventions would be sustained beyond donor support, they had concerns about government financing of demand-side social and behavior change work. CONCLUSION: As political and managerial factors, even more than technical factors, were most linked with successful adoption and scale-up, these processes and systems should be assessed and prioritized from the start. Government leaders, TCI coaches, and other stakeholders can use these findings to shape similar initiatives to sustainably scale social service interventions.