Development and preliminary evaluation of the QUALIKO: an observational quality of life instrument for patients with Korsakoff's syndrome.

Background: To develop a Korsakoff-specific measure of quality of life (QoL), to be rated by professional caregivers, and to field-test its psychometric properties in a sample of patients with Korsakoff's syndrome (KS) living in a specialized nursing home.

Methods: A research version of the QUALIKO was developed based on an existing instrument for dementia (the QUALIDEM), literature review and two rounds of surveys among expert professionals involved in the care for patients with KS. Next, QoL was independently rated using the preliminary QUALIKO for 77 patients with KS by two primary caregivers.

Results: The research QUALIKO consisted of 48 items describing observable behaviors across ten aspects of QoL relevant to patients with KS. Six items demonstrated poor scalability in the field test. The remaining 42 items all formed subscales with moderate to strong scalability according to Mokken scale analysis. Reliability was acceptable to good across both raters for all subscales (Mokken rho's = 0.70-0.90), except for the two 2-item subscales of negative affect and positive self-image (Mokken rho's = 0.47-0.71). Inter-observer agreement was excellent for five subscales (ICCs = 0.75-0.89) and fair to moderate for the other five subscales (ICCs = 0.59-0.72). The multidimensional internal structure was confirmed and all subscales were significantly correlated with primary caregivers' global ratings of QoL except for positive self-image. Missing item values were low and floor and ceiling effects acceptable for most subscales.

Conclusions: The QUALIKO holds promise as a feasible, reliable, and valid measure of QoL in residential KS patients. Future research in larger samples is needed to confirm the psychometric dimensionality of the instrument, to gather normative data and to examine its test-retest reliability.