INTRODUCTION AND

Objective: The Geriatric Depression Scale - 30 (GDS-30) for detecting depressive disorders provides an objective and reliable outcome measure validated by many studies and scientific articles. The aim of the study was to compare the concordance of measurements using the GDS-30 conducted in face-to-face and telephone interviews.

Material and methods: The study design was approved by the Bioethical Committee of the University of Rzeszów (Resolution No. 2022/075). Study participants were community-dwelling older people in south-eastern Poland, aged 60 years and over, with a normal cognitive status. They were divided into 2 groups, each examined with the Geriatric Depression Scale - 30 questionnaire. The first group (G1) was examined first by means of direct contact (A), and the second group (G2) by telephone (B). After an average period of 2 weeks, the study was repeated, this time swapping the method of contact: in G1 telephone contact (B) was used, in G2 face-to-face contact (A).

Results: The study involved a group of 225 people (128 women and 97 men), mean aged 68.2 years, randomly divided into the 2 groups (G1 and G2). Cohen's kappa coefficient analysis showed good (14 questions) to very good (16 questions) concordance for individual responses to questions. Analysis of Krippendorf's alpha coefficient values showed very good concordance for results on the whole questionnaire. Good concordance of the means of measurement was also confirmed by the Bland and Altman method, where more than 95% of the sample was within the 95% concordance limits.

Discussion and conclusions: Findings of the study showed that the GDS-30 questionnaire had a high compliance in both face-to-face and telephone surveys.