Psychometric validation of geriatric depression scale – Short form among bengali-speaking elderly from a rural area of West Bengal: Application of item response theory

Abstract

Background: The geriatric depression scale – short form (GDS-SF) considered an important preliminary screening tool, requires translation in different regional languages and validation, to become of utmost use in Indian context especially in the field level. Objective: The current study aimed to evaluate the psychometric validity of the GDS-SF translated into Bengali among rural elderly population. Methods: The 15-item GDS-SF translated to Bengali language was administered to 206 Bengali speaking geriatrics selected maintaining predecided inclusion and exclusion criteria from villages under a rural block in West Bengal. Latent trait modelling was used to evaluate the psychometric properties of this translated tool. Differential item functioning (DIF) was assessed to measure invariance. Results: The mean age of the participants was 68.77 years (standard deviation 6.81 years). Majority being female (57.77%), Hindu (87.38%), from a joint family background (90.78%). The highest discrimination was observed with item 8 (coefficient 3.682, P < 0.001) followed by item 14 (coefficient 3.020, P < 0.001). Question 2 had least coefficient for difficulty (−1.344, P = 0.013) while item 15 had highest (0.775, P = 0.001). The questionnaire provided maximum information (discrimination) around mean value of latent trait. The total cutoff score of 5 was related nearly to mean latent trait (−0.111). Items 10 and 13 showed consistent DIF across different demographic groups. Conclusion: Psychometric properties of GDS-SF (Bengali) established overall construct and content validity of the tool in this community-based study. Despite some degree of DIF the tool can be used as a preliminary screening method in rural community.

Keywords

• geriatric depression scale
• geriatrics
• item response theory
• reliability
• short form
• validity