Validity and reliability of the depression in old age scale (DIA-S) in Iranian older adults

One of the most common geriatric psychiatric syndromes is depression. The aim of this study was to assess the validity and reliability of the Depression in Old Age Scale (DIA-S) as a self-report screening tool for depressive symptoms in Iranian elders.

The population sample was consisted of 210 older subjects admitted to Hamadan adult day care centers. The DIA-S and a socio-demographic questionnaire were used to gather the data. Concurrent and convergent validity were assessed by Geriatric Depression Scale (GDS-15), and Abbreviated Mental Test score (AMTs), respectively. Measures for internal consistency were calculated with Cronbach's alpha. Factor structure of DIA-S was evaluated by principal component analysis, using varimax rotation with Kaiser normalization. Test-retest reliability was carried out using re-administration DIA-S to 24 participants after a gap of 16days. Independent t-test and ANOVA were used to assessing significance of differences across demographic groups.

The mean score of DIA-S was 3.69 (SD: 1.92, Range: 1-9). The Cronbach's α for DIA-S score was 0.821, indicating a high degree of internal consistency and homogeneity between the DIA-S items. Test-retest correlation on the 24 patients showed excellent results (ranging from 0.748 to 0.946). Factor analysis revealed one component that confirmed the theoretical construction of the scale. Based on the results, statistically significantly higher DIA-S scores with lower incomes were found.

The DIA-S is a valid and reliable self-report screening tool for depressive symptoms in Iranian geriatric population and may be used in clinical and epidemiological studies.