Minor impact of multiple psychiatric symptoms on quality of life (EQ5D) in psychogeriatric patients: a clinical-empirical structural modeling approach.

Background: The relationship of clinical variables for cognitive functioning and other variables such as multiple neuropsychiatric symptoms and quality of life are usually analyzed bivariately and multivariately. In randomized controlled trials analyses are mostly performed on individual outcome variables. To unravel interdependencies of determinants and outcome variables, Structural Equation Modeling (SEM) was applied.

Methods: Using SEM, we explored interdependencies of clinical determinants (MMSE, BI, and NPI-sum severity) and quality of life (EQ5D) in psychogeriatric patients (including dementia) suffering from cognitive problems and multiple neuropsychiatric symptoms.

Results: MMSE and BI showed direct and indirect impact on EQ5D, but the association with NPI-sum severity was minor. The identified model showed that R(2) of EQ5D varied from 0.21 to 0.48.

Discussion: This clinical-empirical study showed that SEM could be utilized to unravel and identify a model of complex direct and indirect effects of MMSE and BI on EQ5D. In relation to NPI-sum severity, however, the validity of EQ5D seemed insufficient in psychogeriatric patients. Consequently, the cost-benefit analyses and cost-effectiveness analyses using quality-adjusted life-year measures of an intervention in psychogeriatric patients with multiple neuropsychiatric symptoms, based on EQ5D, are considered questionable. Construction of a quality of life instrument that is more sensitive with regard to multiple neuropsychiatric symptoms in psychogeriatric patients is highly recommended.