Clinical outcomes and cost-utility analysis of comprehensive geriatric assessment models in hospitalized frail older patients in Thailand

Background: Frailty increases vulnerability to adverse outcomes and healthcare utilization. Comprehensive geriatric assessment (CGA) improves these outcomes in high-income countries, but evidence in resource-constrained settings is limited. This study aimed to assess clinical outcomes and cost-effectiveness of two CGA models (CGA-ward; CGA-consult) compared to usual care in hospitalized frail older adults. Methods: Two data sources from Siriraj Hospital were utilized: A randomized controlled trial comparing CGA-consult with usual care in acute medical wards (September 2019 and March 2024), and a retrospective cohort of patients receiving CGA-ward care in an intermediate care ward (April 2023-June 2024). Outcomes included health utility measured by EQ-5D-5L, Barthel Index, and hospital readmissions over 6 months. Cost-utility analyses were conducted from a societal perspective. Multivariate mixed-effects regression with inverse probability of treatment weighting (IPTW) estimated incremental outcomes and costs for incremental cost-effectiveness ratios (ICERs). Results: Among 226 patients, 45 received CGA-ward, 89 received CGA-consult, and 92 received usual care. CGA-ward significantly improved utility scores (incremental mean: 0.259; 95% CI: 0.140, 0.378) and functional outcomes (mean difference: 37.94; 95% CI: 26.39, 49.48) compared to usual care. From a societal perspective, CGA-consult also showed a modest improvement in utility (incremental mean: 0.093; 95% CI: 0.007, 0.179). CGA-ward and CGA-consult provided US$937 and US$552 savings per patient, with QALY gains of 0.130 and 0.047, respectively. Estimated ICERs were -US$7,208 and -US$11,745 per QALY gained, representing cost-savings for both interventions compared to usual care. Conclusions: CGA-ward represents an intermediate care (IMC) model providing improved clinical and economic benefits, supporting its implementation in resource-limited settings. CGA-consult remains a viable alternative where ward-based care is not feasible, highlighting the value of integrating CGA into routine hospital care for frail older adults. Trial registration: The parent randomized controlled trial was registered with the Thai Clinical Trials Registry (TCTR20190910002) on 10 September 2019.