Assessing the Relationship between Health Utilities, Quality of Life, and Health Care Costs in Alzheimer's Disease: The CATIE-AD Study

Objectives: To examine the relationship between multiple measures of health care costs and health utilities, quality of life, and other factors in Alzheimer's Disease (AD). Research Design: Data were obtained via caregiver proxy at baseline and 3- 6- and 9-months following study entry on 421 patients with AD who participated in the CATIE-AD trial of antipsychotic medication. Spearman rank correlations and mixed models (using logged costs) were used to examine the correlates of health care costs. Measures: Health care costs include inpatient hospital, nursing home, residential care, combined institutional, outpatient, ancillary drug, and total costs. Correlates include the AD-Related Quality of Life Scale (ADRQoL) and Health Utilities Index (HUI)-III. Results: Total monthly health care costs averaged $1,205 during the study period. Each .10 increment on the HUI-III (stronger health utilities) was associated with a decrease in institutional, outpatient, and total costs of 9.7%, 6.9%, and 8.2%, respectively. Each one-point increase on the ADRQoL (better quality of life) was associated with an increase in ancillary drug and total costs of 1.7% and 2.1%. Total costs tended to be lower for female patients (β=-.325) with better physical functioning (β=-.017) but higher for less cognitively impaired individuals (β=.038). Older (β=.025), non- Hispanic Whites (β=.575) tended have higher outpatient costs, those with better physical functioning lower institutional costs (β=-.019). Drug costs tended to be lower for females (β=-.427) and higher for those with greater psychiatric symptoms (β=.016). Conclusion: The HUI-III findings suggest that health utilities could be combined with other known correlates of costs to inform resource allocation cost-effectiveness analyses associated with AD. The ADRQoL findings suggest that better quality of life may make it easier for caregivers to identify problems and/or to access and maintain certain types of health system contacts.