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

Abstract

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). 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. 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. 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 (beta=-.325) with better physical functioning (beta=-.017) but higher for less cognitively impaired individuals (beta=.038). Older (beta=.025), non-Hispanic Whites (beta=.575) tended have higher outpatient costs, those with better physical functioning lower institutional costs (beta=-.019). Drug costs tended to be lower for females (beta=-.427) and higher for those with greater psychiatric symptoms (beta=.016). 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.