Validation of PDQ-8 as an independent instrument in English and Chinese.
Previous validation studies on the PDQ-8, a brief disease-specific quality of life instrument, were performed with the PDQ-8 nested in the original PDQ-39. Such an approach may influence patient responses and the psychometric properties of the PDQ-8. We therefore undertook this study to validate the PDQ-8 when administered independently in English and Chinese and found good item-to-scale correlations (correlation coefficient: 0.44-0.68) and internal consistency (Cronbach's alpha: 0.81, 0.87). Factor analyses yielded a component on which all 8 questions were substantially loaded (loading range: 0.55-0.77). Scree plots also showed the one-factor solution thereby validating the PDQ-8 summary index. Construct validation against the Hoehn and Yahr stage and UPDRS motor scores showed significant correlations between higher PDQ-8 summary index and increased disease severity in both English and Chinese versions. Our results show the PDQ-8 to be a valid and reliable disease-specific HRQoL instrument for PD when used independently of the PDQ-39.
Tan
Louis C S
LC
Department of Neurology and Parkinson's Disease and Movement Disorders Centre, National Neuroscience Institute, USA National Parkinson Foundation Centre of Excellence, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore. louis_tan@nni.com.sg
Lau
Puay-Ngoh
PN
Au
Wing-Lok
WL
Luo
Nan
N
D000368:Aged; D044466:Asian People; D018450:Disease Progression; D005260:Female; D006801:Humans; D007802:Language; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000592:standards*; D010300:Parkinson Disease / Q000523:psychology*; D011237:Predictive Value of Tests; D011788:Quality of Life / Q000523:psychology*; D015203:Reproducibility of Results; D012846:Singapore; D011795:Surveys and Questionnaires / Q000592:standards*