Validation of the Glasgow Antipsychotic Side-Effect Scale (GASS) in Greece

Abstract

The aim of the present study was to evaluate the linguistic adaptation and psychometric validation into the Greek language of the GASS scale for the assessment of side effects in patients treated with second generation antipsychotic medication. The GASS scale takes 5 minutes to complete (21 items for men and women) and contains self-explanatory questions in everyday plain English while providing a structured systematic method of reviewing antipsychotic side effects. The translation and cultural adaptation of the questionnaire was performed according to international standards. Internal consistency using the Cronbach α coefficient and test-retest reliability using the intraclass correlation coefficient (ICC) was used to assess the reliability of the instrument. Patient's sample consisted of 80 participants with a mean age of 42.6 years. Internal consistency and intraclass correlation coefficient were adequate (Cronbach α = 0.79 and ICC = 0.96). The test-retest percent agreement for the aforementioned categories was 95.9. Agreement was satisfactory according to Kappa coefficient which was equal to 0.78 (p<0.001).The Greek validation of the GASS scale shows appropriate feasibility, reliability, and discriminative performance as a patient-reported outcome to be used for the assessment of the impact of side effects on patients with schizophrenia.