Mapping Models of Tirzepatide Delivery for Obesity Management in Primary Care Settings

Objectives To evaluate the early implementation of tirzepatide for the management of obesity in primary care in England, including variations in Integrated Care Board (ICB) service delivery models, access criteria, and initial prescribing activity following national policy introduction (June 2025). This paper reports the initial phase of a wider mixed methods national evaluation of tirzepatide delivery models for initial priority cohorts defined in NHS England interim commissioning guidance. Design National study combining 1) mapping of ICB implementation plans using a questionnaire, publicly available data and documents, and stakeholder discussions, and 2) analysis of English Prescribing Dataset (EPD) to investigate tirzepatide prescribing trendsusing interrupted time-series methods to compare monthly prescriptions before and after June 2025 (implementation start) against a synthetic control series based on semaglutide prescribing. Setting ICBs across England. Participants 23/42 ICBs (55%) responded, of which 13 also took part in stakeholder meetings. For 17 ICBs (40%), we additionally extracted information from publicly available documents. Main outcome measures Descriptions of service delivery models, access criteria, and ICB characteristics; stakeholder-reported implementation challenges; and prescribing trends over time. Results We were able to categorise models of care for 40/42 ICBs. A general practice-led delivery model was most commonly planned (18/40; 45%), followed by community/local-based delivery (8; 20%), custom models (8; 20%), and specialist weight management service (SWMS) community outreach (6; 15%). Four ICBs (10%) planned to use more than one model of care. Most ICBs reported following national priority cohort eligibility criteria 31/39 (79%), while eight (21%) applied additional prioritisation criteria due to funding constraints. Stakeholder discussions highlighted variation in the interpretation of model definitions, variation in operationalisation, and challenges related to affordability, insufficient workforce capacity, and tight timelines, with some ICBs not yet prescribing at the time of stakeholder meetings (November 2025). Analyses of EPD showed a steady increase in tirzepatide prescribing over time, with no evidence that the June 2025 policy implementation date produced any additional increase beyond background diabetes-related trends. Conclusions Early implementation of tirzepatide prescribing in primary care has been characterised by heterogeneous service models, local adaptations of access criteria, and slow implementation of obesity-related prescribing. Findings highlight the challenges of implementing new pharmacological treatments including patient management within routine care and the need for clear guidance, realistic timelines, and system capacity. Ongoing evaluation is needed to understand how service models evolve and implications for access, equity, and outcomes.