Which Components of Integrated Care Are Associated with Reduced Hospital Utilisation in Adults with Chronic Disease? A Systematic Review with Narrative Synthesis

Background: Cardiovascular disease, type 2 diabetes, chronic obstructive pulmonary disease (COPD), and chronic heart failure account for a disproportionate share of hospital admissions, readmissions, and health-service expenditure worldwide. Integrated care coordinating services across primary, specialist, hospital, and community settings has been widely promoted as a remedy, but the effectiveness literature has repeatedly evaluated “integrated care” as a single, undifferentiated intervention. What remains unresolved is which specific intervention components drive the reductions in hospital utilisation that some, but not all, integrated-care programmes achieve. Objective: To identify, from systematic reviews, meta-analyses, and primary evaluation studies, which components of integrated care are most consistently associated with reduced hospital admissions, readmissions, emergency department (ED) use, and costs among adults with chronic disease, and to determine what implementation factors explain variation in effectiveness across components and conditions. Methods: A systematic review with narrative synthesis (synthesis without meta-analysis, SWiM) was conducted on systematic reviews, meta-analyses, and primary evaluation studies retrieved through structured literature searches, following PRISMA 2020 guidance for reviews of reviews. Study design, intervention components, population, utilisation outcomes, clinical outcomes, and cost outcomes were extracted and synthesised by intervention component rather than by individual study, under the guiding frameworks of the Chronic Care Model (CCM) and the Rainbow Model of Integrated Care (RMIC). Results: Thirteen sources met eligibility criteria. Interventions combining multidisciplinary team-based follow-up, structured transitional-care or discharge-management components, and cross-setting care coordination were the components most consistently associated with reduced utilisation. In this subset of evidence, patients with cardiovascular disease had a 37% reduction in hospitalization (RR 0.63, 95% CI 0.56–0.71), and patients with cardiovascular disease or type 2 diabetes had a 47% reduction in adverse events (RR 0.53, 95% CI 0.27–1.05). Transitional-care and post-discharge follow-up components reduced 30-day rehospitalisation by 21–37% depending on intensity and patient risk. A four-year, multi-component chronic-disease-management programme incorporating care coordination produced an 11.4% reduction in admissions, a 36.7% reduction in readmissions, and a 17.2% reduction in bed-days. Single-component self-management-support interventions, by contrast, showed less consistent utilisation benefit, although they improved intermediate clinical outcomes. Cost findings were more heterogeneous than utilisation findings across components, with net savings concentrated in high-risk heart-failure populations. Conclusion: The evidence indicates that hospital-utilisation benefits from integrated care are not uniform across intervention types, but are concentrated in programmes combining multidisciplinary teams, structured transitional care, and risk-stratified follow-up spanning more than one care setting. Evidence for these components is strongest in cardiovascular disease and heart failure and weaker and less consistent for type 2 diabetes and chronic respiratory disease. Future research should prioritise component-specific, standardised, longer-follow-up evaluations rather than further whole-programme effectiveness studies.