Patterns of Vulnerability: Frailty, Multimorbidity, and Physical Health-Related Quality of Life in Institutionalised Older Adults

Background/Objectives: Population ageing is accompanied by an increasing burden of multimorbidity and frailty, both of which are consistently associated with poorer health-related quality of life (QoL). Although several geriatric domains influence QoL in older adults, their combined association remain insufficiently explored in institutionalised populations. This study aimed to examine the independent and combined associations between age, multimorbidity, frailty, and QoL in institutionalised older adults and to explore which quality-of-life domain was most strongly associated with geriatric assessment variables. Methods: A cross-sectional study was conducted in 72 institutionalised older adults in Spain. Multimorbidity (number of chronic conditions), frailty (Fried phenotype), functional status, nutritional status, fall risk, and QoL were assessed using validated instruments, including the World Health Organization Quality of Life questionnaire. Pearson correlations and canonical correlation analysis were used to examine relationships between geriatric assessment variables and QoL domains. Analysis of variance and regression tree were subsequently applied to explore associations affecting the Physical Health domain. Results: A correlation analysis identified the Physical Health domain as the QoL dimension most strongly associated with geriatric variables. On the other hand, frailty, age and number of chronic diseases turned out to be the most explanatory in our study and were classified: the first according to the standard protocol, and the other two using a regression tree. Then, a three-way additive ANOVA explained 36.4% of the variance, with age as main influential. Namely, we estimate that the poorest QoL occurs in subjects over 84 who have more than three chronic conditions and are classified as frail. However, this is not a validated clinical decision rule since these cutoff points may vary in other samples. Conclusions: In this sample of institutionalised older adults, age emerged as the main variable associated with lower physical QoL, multimorbidity contributes to the cumulative burden of disease, and frailty may reflect the systemic decline in physiological reserves.