Dementia disorders are associated with poor quality of life of patients. Generic tools have been shown to hardly capture main aspects of these conditions. The aim was to validate the Spanish version of the two dementia-specific health-related quality of life scales that make up the DEMQOL system: DEMQOL and DEMQOL-Proxy.

One-hundred-nineteen subjects with dementia according to DSM-III-R/DSM-IV, and their caregivers from six centers participated in the study. The following patient-reported information was obtained by interview: demographics, subjective perception of health, comorbidity, depressive symptoms (GDS-15), functional ability (Barthel Index), and generic (WHOQOL-BREF) and dementia-specific (DEMQOL) health-related quality of life. Proxy-reported information about the patient's quality of life was obtained by interview of a family caregiver using the DEMQOL-Proxy.

The Spanish version of DEMQOL showed good psychometric properties. Acceptability was good, with 5% missing information. Internal consistency (Cronbach alpha=0.85) and test-retest reliability (ICC=0.71) were also good. A priori associations between DEMQOL and the psychological and physical domains of the WHOQOL-BREF, the GDS-15 and the Barthel Index were supported, indicating good construct validity. Associations between DEMQOL-Proxy and the measures mentioned were weaker. The factor solution for the Spanish version of DEMQOL showed a three factor solution that accounted for 44.4% of the total variance; and a four-factor solution for DEMQOL- Proxy that accounted for 53.3% of the total variance.

As per the results found, the Spanish version of DEMQOL and DEMQOL-Proxy are reliable and valid in patients with mild/moderate dementia who are living at home.