Acceptability, appropriateness, sustainment, and implementation cost of a multicomponent strategy to increase HPV vaccination in pediatric primary care: secondary results of a cluster-randomized trial

Background Implementation outcomes and cost are as essential as clinical effectiveness for evidence-based practice adoption, yet few HPV vaccination improvement studies have assessed both using validated tools. Moreover, sustainment remains understudied in randomized controlled trials beyond the active implementation period. This gap limits the ability of health systems to make informed decisions about adoption and scale-up of the implementation strategy. Objective To assess implementation outcomes, including acceptability, appropriateness, sustainment, and estimate implementation costs from two stakeholder perspectives for a multicomponent strategy designed to improve HPV vaccination in pediatric primary care practices. Methods We conducted a secondary analysis of a 24-month cluster randomized controlled trial involving 20 pediatric practices. Implementation outcomes were assessed among providers using validated tools post-implementation. Because implementation outcomes were assessed following exposure and at different time points across study groups, analyses reflect provider perceptions of the strategy rather than causal comparisons. Implementation costs for the 10 intervention practices were evaluated from two perspectives: practice facilitators and practice personnel. Costs were calculated using personnel time multiplied by national wage rates from the 2023 U.S. Bureau of Labor Statistics. We used a micro-costing approach to estimate implementation resource use. Cost-effectiveness was assessed as cost per percentage-point improvement per practice and cost per additional adolescent vaccinated. Results Among 43 post-implementation survey responses (60% response rate), mean scores of acceptability (4.33 of 5) and appropriateness were high (4.37 of 5), with positive sustainment (3.95 of 5). Mean implementation cost was $10,021 per practice, requiring 93 h of facilitator time and 44 h of practice personnel time per practice over 24 months. Cost per additional adolescent completing the HPV vaccination series was $527 (facilitator: $238, practice: $289). These findings suggest favorable implementation outcomes alongside transparent, dual-perspective resource estimates. Conclusions The multicomponent strategy demonstrated high acceptability and appropriateness among providers, minimal disruption to clinical operations, and maintained positive sustainment ratings 12 months post-implementation. By reporting provider perceived implementation outcomes with detailed cost data from both implementer and practice perspectives, this study provides actionable evidence to inform feasibility and scalability of HPV vaccination implementation strategies in pediatric primary care. Trial registration ClinicalTrials.gov NCT04180462.