Reliability and Validity of the Korean Short-form Eight-item Parkinson’s Disease Questionnaire (PDQ-8)

Reliability and Validity of the Korean Short-form Eight-item Parkinson’s Disease Questionnaire (PDQ-8)

Objectives: This study aimed to determine the reliability and validity of the Korean Parkinson’s disease questionnaire (PDQ-8) using a standard shortform validation approach. Methods: This cross-sectional psychometric study evaluated 80 outpatients with PD who completed the Korean 39-item Parkinson’s disease questionnaire (PDQ-39) and PDQ-8 tools in random order. The summary index (SI) was calculated for the PDQ-39 (PDQ-39SI) and PDQ-8 (PDQ-8SI). A neurologist performed evaluations using the Hoehn and Yahr (HY) scale, unified Parkinson’s disease rating scale (UPRDS motor), mini-mental state examination (MMSE), Montreal cognitive assessment (MoCA), the clinical dementia rating (CDR), and global deterioration scale (GDS). Results: The PDQ-8SI exhibited appropriate floor effect (2.5%) and ceiling effect (1.3%), with acceptable internal consistency reliability (Cronbach’s α= 0.88), item-total correlations (0.48-0.77), and inter-rater reliability (Kappa coefficient = 0.53). The PDQ-8 loaded one factor (Eigen value = 4.35, 54.51% of the variance) and had broadly similar factor loadings (0.585-0.847). The PDQ-8 had mostly goodness of fit (GFI = 0.932, NFI = 0.914, TLI = 0.973, IFI = 0.981, CFI = 0.981, and RMSEA = 0.056). The PDQ-8SI and PDQ-8 items exhibited good correlations with each other (all p< 0.05) and the PDQ-39SI (r = 0.91, p< 0.001). The PDQ-8SI was correlated with levodopa dose (r = 0.28, p= 0.028), HY score (r = 0.44, p= 0.001), UPRDS motor (r = 0.45, p= 0.007), MMES (r = -0.28, p= 0.047), MoCA (r = -0.49, p= 0.006), GDS (r = 0.33, p= 0.025), and CDR (r = 0.40, p= 0.007), respectively. Conclusions: The PDQ-8 appears to be reliable and valid. It may be useful for quickly and easily evaluating the patient’s perspectives regarding the disease’s impacts, which may guide nursing practice and future research.

Objectives: This study aimed to determine the reliability and validity of the Korean Parkinson’s disease questionnaire (PDQ-8) using a standard shortform validation approach. Methods: This cross-sectional psychometric study evaluated 80 outpatients with PD who completed the Korean 39-item Parkinson’s disease questionnaire (PDQ-39) and PDQ-8 tools in random order. The summary index (SI) was calculated for the PDQ-39 (PDQ-39SI) and PDQ-8 (PDQ-8SI). A neurologist performed evaluations using the Hoehn and Yahr (HY) scale, unified Parkinson’s disease rating scale (UPRDS motor), mini-mental state examination (MMSE), Montreal cognitive assessment (MoCA), the clinical dementia rating (CDR), and global deterioration scale (GDS). Results: The PDQ-8SI exhibited appropriate floor effect (2.5%) and ceiling effect (1.3%), with acceptable internal consistency reliability (Cronbach’s α= 0.88), item-total correlations (0.48-0.77), and inter-rater reliability (Kappa coefficient = 0.53). The PDQ-8 loaded one factor (Eigen value = 4.35, 54.51% of the variance) and had broadly similar factor loadings (0.585-0.847). The PDQ-8 had mostly goodness of fit (GFI = 0.932, NFI = 0.914, TLI = 0.973, IFI = 0.981, CFI = 0.981, and RMSEA = 0.056). The PDQ-8SI and PDQ-8 items exhibited good correlations with each other (all p< 0.05) and the PDQ-39SI (r = 0.91, p< 0.001). The PDQ-8SI was correlated with levodopa dose (r = 0.28, p= 0.028), HY score (r = 0.44, p= 0.001), UPRDS motor (r = 0.45, p= 0.007), MMES (r = -0.28, p= 0.047), MoCA (r = -0.49, p= 0.006), GDS (r = 0.33, p= 0.025), and CDR (r = 0.40, p= 0.007), respectively. Conclusions: The PDQ-8 appears to be reliable and valid. It may be useful for quickly and easily evaluating the patient’s perspectives regarding the disease’s impacts, which may guide nursing practice and future research.