The local reliability of the 15-item version of the Geriatric Depression Scale: An item response theory (IRT) study

Francesca Chiesi; Caterina Primi; Martina Pigliautile; Sara Ercolani; Manuela Conestabile Della Staffa; Annalisa Longo; Virginia Boccardi; Patrizia Mecocci

doi:10.1016/j.jpsychores.2017.03.013

The local reliability of the 15-item version of the Geriatric Depression Scale: An item response theory (IRT) study

J Psychosom Res. 2017 May:96:84-88. doi: 10.1016/j.jpsychores.2017.03.013. Epub 2017 Mar 23.

Authors

Francesca Chiesi¹, Caterina Primi², Martina Pigliautile³, Sara Ercolani³, Manuela Conestabile Della Staffa³, Annalisa Longo³, Virginia Boccardi³, Patrizia Mecocci³

Affiliations

¹ Department of Neuroscience, Psychology, Drug, and Child's Health (NEUROFARBA), Section of Psychology, University of Florence, Italy. Electronic address: francesca.chiesi@unifi.it.
² Department of Neuroscience, Psychology, Drug, and Child's Health (NEUROFARBA), Section of Psychology, University of Florence, Italy.
³ Institute of Gerontology and Geriatrics, Department of Medicine, University of Perugia, Italy.

PMID: 28545797
DOI: 10.1016/j.jpsychores.2017.03.013

Abstract

The 15-item version of the Geriatric Depression Scale (GDS-15) is a self-report screening instrument widely used. The current study aimed at providing evidence of the measurement precision of the GDS-15 applying Item Response Theory (IRT). The relative contribution of each item and the reliability of the whole scale in measuring the trait level around the cutoffs were investigated employing data collected from a sample consisting of 1344 old people (M=76.44years, SD=5.13; 58.7% women) involved in a large gerontological research project. The unidimensional two-parameter (2PL) logistic model was employed to item estimate location and slope parameters as well as the Test Information Function (TIF). Nine out of fifteen items were located around the cutoffs and the slopes showed that the majority of the items had substantial discrimination ability. The TIF peaked in correspondence of the cutoffs attesting the good local reliability of the scale. These findings support to the utility of the GDS-15 in detecting depression among older people.

Keywords: Depression; Elderly; IRT; Reliability; Screening test.

MeSH terms

Aged
Depressive Disorder / diagnosis*
Female
Geriatric Assessment / methods*
Humans
Male
Reproducibility of Results
Sensitivity and Specificity