IMPLEMENTING MULTICOMPONENT INTERVENTIONS TO TREAT BLOOD DONORS WITH FAMILIAL HYPERCHOLESTEROLEMIA - PROJECT SUMMARY Familial Hypercholesterolemia (FH) remains woefully underdiagnosed and undertreated in the US. Recent work from the PI demonstrated the ability to identify blood donors with FH at a similar prevalence as would be expected in the general population. The overall objective in this mixed methods study is to apply implementation strategies to improve treatment of blood donors with FH. The central hypothesis is that the blood donation system can be an effective portal to increase receipt of treatment for individuals with FH. The central hypothesis will be tested by pursuing four specific aims: 1) identify barriers and facilitators to receipt of (low-density lipoprotein cholesterol) LDL-C treatment in blood donors with FH to inform implementation strategy development, 2) develop and produce an implementation strategy bundle to increase LDL-C treatment in blood donors with FH, 3) conduct a Type 2 implementation-effectiveness trial for LDL-C lowering in a community-based blood donation center, and 4) evaluate the implementation bundle using mixed methods. This research will be guided by the Consolidated Framework for Implementation Science Research (CFIR), and will use Implementation Mapping, a theory- and evidence-based process, to develop, implement, and evaluate these treatment enhancing strategies. In the first aim, semi-structured interviews will be used to elicit barriers and facilitators of statin treatment from key stakeholders including: a) blood donors with FH b) family members of donors c) blood donation personnel d) community physicians. Stakeholder feedback will be iteratively integrated to develop, produce, and refine an implementation strategies bundle in the second aim, that will be tested in Aim 3. The third aim consists of a two-arm randomized trial among blood donors with FH comparing a) usual notification of high cholesterol or b) the implementation strategies bundle from Aim 2 with the primary outcome of difference in change in LDL-C levels from baseline to 6 months. The fourth aim will assess the acceptability, appropriateness, and feasibility of the implementation strategy bundle and will inform development of a dissemination package to implement an FH program in other blood donor centers. The research proposed in this application is innovative, in our opinion, because it incorporates the blood donor program, an entirely new approach to identifying and treating FH. This novel portal of enhancing FH treatment involves younger individuals who are less likely to seek regular medical care and complements traditional strategies focusing on patients with medical homes. Ultimately, if successful, this program, informed by implementation science methods, can be rapidly scaled to blood donation centers nationally involving 6.4 million donors annually, having an immediate impact on gaps in FH care.