A Cost-Effectiveness Model for Frail Older Persons: Development and Application to a Physiotherapy-Based Intervention.

INTRODUCTION: The clinical importance of frailty is increasing. Existing economic evaluations of interventions to manage frailty have limited time horizons, but even in older populations there may be important longer-term differences in costs and outcomes. This paper reports on the development of a cost-effectiveness model to predict publicly funded health and aged care costs and quality-adjusted life years (QALYs) over the remaining lifetime of frail Australians and a model-based cost-utility analysis of a physiotherapy-based intervention for frail individuals. METHODS: A cohort-based state transition (Markov) model was developed to predict costs and QALYs over the remaining lifetime of a frail population. Frailty is defined using the phenotypic definition of frailty, and the model comprises health states that describe frailty status, residential status, the experience of bone fractures and depression, and death. Model input parameters were estimated and calibrated using the Dynamic Analyses to Optimise Ageing dataset, supplemented with data from the published literature. RESULTS: The cost-effectiveness model was subject to a range of validation approaches, which did not negate the validity of the model. The evaluated physiotherapy-based frailty intervention has an expected incremental cost per QALY gained of Australian $8129 compared to usual care, but there is a probability of 0.3 that usual care is more effective and less costly than the intervention. DISCUSSION: Frailty reduces quality of life, is costly to manage and it's prevalence is increasing, but new approaches to managing frailty need to demonstrate value for money. The value of the reported cost-effectiveness model is illustrated through the estimation of all important costs and effects of a physiotherapy-based frailty intervention, which facilitates comparisons with funding decisions for other new technologies in Australia.