A longitudinal evaluation of the Center for Epidemiologic Studies-Depression scale (CES-D) in a Rheumatoid Arthritis Population using Rasch Analysis

Tanya Covic,Alan Tennant,Julie F Pallant,Philip G Conaghan

doi:10.1186/1477-7525-5-41

Abstract

BackgroundThe aim of this study was to test the internal validity of the total Center for Epidemiologic Studies-Depression (CES-D) scale using Rasch analysis in a rheumatoid arthritis (RA) population.MethodsCES-D was administered to 157 patients with RA over three time points within a 12 month period. Rasch analysis was applied using RUMM2020 software to assess the overall fit of the model, the response scale used, individual item fit, differential item functioning (DIF) and person separation.ResultsPooled data across three time points was shown to fit the Rasch model with removal of seven items from the original 20-item CES-D scale. It was necessary to rescore the response format from four to three categories in order to improve the scale's fit. Two items demonstrated some DIF for age and gender but were retained within the 13-item CES-D scale. A new cut point for depression score of 9 was found to correspond to the original cut point score of 16 in the full CES-D scale.ConclusionThis Rasch analysis of the CES-D in a longstanding RA cohort resulted in the construction of a modified 13-item scale with good internal validity. Further validation of the modified scale is recommended particularly in relation to the new cut point for depression.

Highlights

The aim of this study was to test the internal validity of the total Center for Epidemiologic Studies-Depression (CES-D) scale using Rasch analysis in a rheumatoid arthritis (RA) population
The Center for Epidemiologic Studies-Depression (CESD) scale is one of the commonly used depression measurement tools originally developed for use in the general population [7]
The probability p that a person n will affirm an item i is a logistic function of the difference between the person's ability θ and the difficulty of the item b, and only a function of that difference: Exploratory and confirmatory factor analyses have been commonly used to test the CES-D latent structure, these techniques are sample dependent [8], and tend to produce different findings [13]

Summary

Introduction

The aim of this study was to test the internal validity of the total Center for Epidemiologic Studies-Depression (CES-D) scale using Rasch analysis in a rheumatoid arthritis (RA) population. The use of self-report scales, while not substituting for a psychiatric clinical assessment, may be useful as screening tools to identify patients with RA who may be at risk of depression, and to use as an outcome measure. The Center for Epidemiologic Studies-Depression (CESD) scale is one of the commonly used depression measurement tools originally developed for use in the general population [7]. It has been found to be valid and reliable in identification of individuals at high risk of developing major depression in clinical populations including RA [8], brain injury [9], multiple sclerosis [10], cancer [11] and stroke [12]

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