Rights statement: This is the peer reviewed version of the following article: Maltby, J., Dale, M., Underwood, M., Simpson, J. and the REGISTRY investigators of the European Huntington's Disease Network (2017), Irritability in Huntington's Disease: Factor Analysis of Snaith's Irritability Scale. Mov Disord Clin Pract, 4: 342–348. doi:10.1002/mdc3.12424 which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/mdc3.12424/abstract This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
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Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Irritability in Huntington’s Disease
T2 - factor analysis of Snaith’s Irritability scale
AU - Maltby, John
AU - Dale, Maria
AU - Underwood, Mandy
AU - Simpson, Jane
N1 - This is the peer reviewed version of the following article: Maltby, J., Dale, M., Underwood, M., Simpson, J. and the REGISTRY investigators of the European Huntington's Disease Network (2017), Irritability in Huntington's Disease: Factor Analysis of Snaith's Irritability Scale. Mov Disord Clin Pract, 4: 342–348. doi:10.1002/mdc3.12424 which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/mdc3.12424/abstract This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
PY - 2017/5
Y1 - 2017/5
N2 - BackgroundElevated levels of irritability are reported to occur in a number of neurological conditions, including Huntington's disease (HD), a genetic neurodegenerative disorder. Snaith's Irritability Scale (SIS) is used within HD research, but no psychometric evaluation of this instrument has previously been undertaken. Therefore, the current study aimed to analyze the factor structure of this scale among an HD population.MethodsExploratory and confirmatory factor analysis were used to examine the structural properties of SIS using responses from 1,264 HD gene expansion carriers, across 15 European countries, who were engaged in the REGISTRY 3 study.ResultsAn exploratory factor analysis of a subsample of the data suggested a two-factor interpretation of the data comprising “temper” and “self-harm.” Eight possible models were tested for goodness of fit using confirmatory factor analysis. Two bifactor models, testing general and group factors in the structure of the scale, provided an equivocal “good” fit to the data. The first comprised a general irritability factor and two group factors (as originally proposed using SIS): outward irritability and inward irritability. The second comprised a general irritability factor and two group factors (as proposed by the exploratory factor analysis): temper and self-harm. The findings from both models suggested that the loadings of items were higher on the general factor.ConclusionsBifactor models are proposed to best consider the structure of the SIS, with findings suggesting that an overall score should be used to measure irritability within HD populations.
AB - BackgroundElevated levels of irritability are reported to occur in a number of neurological conditions, including Huntington's disease (HD), a genetic neurodegenerative disorder. Snaith's Irritability Scale (SIS) is used within HD research, but no psychometric evaluation of this instrument has previously been undertaken. Therefore, the current study aimed to analyze the factor structure of this scale among an HD population.MethodsExploratory and confirmatory factor analysis were used to examine the structural properties of SIS using responses from 1,264 HD gene expansion carriers, across 15 European countries, who were engaged in the REGISTRY 3 study.ResultsAn exploratory factor analysis of a subsample of the data suggested a two-factor interpretation of the data comprising “temper” and “self-harm.” Eight possible models were tested for goodness of fit using confirmatory factor analysis. Two bifactor models, testing general and group factors in the structure of the scale, provided an equivocal “good” fit to the data. The first comprised a general irritability factor and two group factors (as originally proposed using SIS): outward irritability and inward irritability. The second comprised a general irritability factor and two group factors (as proposed by the exploratory factor analysis): temper and self-harm. The findings from both models suggested that the loadings of items were higher on the general factor.ConclusionsBifactor models are proposed to best consider the structure of the SIS, with findings suggesting that an overall score should be used to measure irritability within HD populations.
KW - factor analysis
KW - Huntington
KW - disease
KW - SIS
KW - irritability
KW - Snaith
U2 - 10.1002/mdc3.12424
DO - 10.1002/mdc3.12424
M3 - Journal article
VL - 4
SP - 342
EP - 348
JO - Movement Disorders
JF - Movement Disorders
SN - 0885-3185
IS - 3
ER -