Testing a Conceptual Model of Physiologic Reserve, Intrinsic Capacity, and Physical Resilience in Hospitalized Older Patients: A Structural Equation Modelling

Introduction: The relationship among physiologic reserve, intrinsic capacity, and physical resilience has not been examined, and a conceptual model that includes these key determinants of healthy ageing is needed. This study aimed to test a conceptual model using real-world data to determine the relationships among physiologic reserve, intrinsic capacity, physical resilience, and clinical outcomes. Methods: This longitudinal study was conducted at a 1,343-bed tertiary-care medical centre. Patients were eligible for inclusion if they were 65 years of age or older and able to communicate independently. Demographic factors, cumulative illness rating scale for geriatrics [CIRS-G] (assessing physiologic reserve), intrinsic capacity, physical resilience instrument for older adults [PRIFOR] (assessing physical resilience), and clinical frailty scale [CFS] were collected at admission. The CFS and EuroQoL 5-dimension 3-level questionnaire [EQ5D] were administered at discharge. Results: The mean age of the 413 patients was 76.34 ± 6.72 (52.5% female). Two conceptual models were identified and supported. Specifically, the path coefficients in the two models showed that the CIRS-G had diverse associations with each intrinsic capacity domain, and that all intrinsic capacity domains (except vitality) were significantly associated with PRIFOR. Moreover, PRIFOR was significantly associated with follow-up CFS, baseline control, and EQ5D scores. Conclusion: Physiologic reserve positively correlated with the cognitive and locomotive domains of intrinsic capacity. Moreover, older patients with better intrinsic capacity may have improved physical resilience, which may lead to better clinical outcomes. Efforts to improve the intrinsic capacity and physical resilience of older patients are necessary to promote healthy ageing.