Barriers and facilitators to scale-up of hospital-at-home: a 3-year observational cohort study

Hospital-at-Home (HaH) delivers hospital-level acute care in patients’ homes, improving patient experience and cost-efficiency. Despite these advantages, scaling HaH remains challenging, and determinants of successful scale-up are poorly understood. The aim of this study is to examine contextual determinants and scaling strategies associated with the scale-up of a HaH service. A retrospective observational cohort study grounded in implementation theory was conducted from May 2022 to April 2025 to examine the planned scale-up of a HaH service in western Singapore, across three phases: “developing the scalable unit” (6–25 beds), “test of scale-up” (25–50 beds), and “go to full scale” (50–90 beds). Monthly outcomes mapped to the RE-AIM framework (Reach, Effectiveness, Adoption, Implementation) were assessed alongside contextual factors and scaling strategies informed by the Exploration, Preparation, Implementation, Sustainment (EPIS) framework. Linear and Poisson regression models examined associations between context, strategies and RE-AIM outcomes. Over 36 months, 3,908 patients were admitted (Phase 1 = 792; Phase 2 = 2,069, Phase 3 = 1,047). Reach, defined as proportion of virtual beds relative to the total bed capacity of referring hospitals rose from 0.6% to 3.3%. Adoption, defined as number of unique referring physicians, rose from 43 to 151. Effectiveness measures, e.g. 30-day readmission rates and implementation measures, e.g. number of home visits per patient per day did not change significantly over time. Regression analyses indicated higher bed occupancy rates of referring hospitals were negatively associated with reach, defined as service volumes (MD -0.10, 95% CI -0.13 to -0.06, p <.001). In contrast, higher adoption, defined as number of referring physicians, was positively associated with number of staff on service (MD 1.01, 95% CI 1.01 to 1.02, p <.001), number of active clinical pathways (MD 1.05, 95% CI 1.05 to 1.06, p <.001), and the introduction of new quality and safety processes (MD 1.22, 95% CI 1.17 to 1.26, p <.001). Consistent with the positive associations observed between staffing levels and Reach/Adoption, and between physician-targeted strategies (new clinical pathways, quality and safety processes) and Adoption, our findings highlight the importance of [1] hiring and training staff [2], targeted strategies at referring physicians, and [3] enhancing quality and safety processes, as key determinants of scaling HaH. Health system leaders and policymakers should prioritise flexible bed-capacity planning, sustained workforce investment, and aligned referral and quality governance to enable reliable, system-wide scale-up of HaH services.