Reliability and validity of PDQ-39: a quality-of-life measure for patients with PD in China

The syndromes of Parkinson’s disease (PD) have impacts on health-related quality of life (HRQL). The 39-item Parkinson’s disease
Questionnaire (PDQ-39) was the first specific and a consistent instrument for the evaluation of HRQL in PD patients.

To test the reliability and validity of Chinese version PDQ-39.

Hundred and twenty-six PD without cognitive impairment were enrolled. The Chinese version of SF-36 was used to evaluate the
congruent validity of PDQ-39 between related domains. Both PDQ-39 and SF-36 scales were fulfilled by the patients themselves.

Five of eight subscales of PDQ-39 met the acceptable standards of reliability (Cronbach’s α coefficient >0.80), while the
other three subscales (cognition, communication, and bodily discomfort) failed to reach the above standards as reported by
the others. All the item-to-subscale correlations (range: 0.457–0.887) met the minimal acceptable item convergent validity
criterion of 0.40 (P < 0.001). Correlation between PDQ-39 subscales and scales of the SF-36 had high negative correlations with a range of −0.759
to −0.124. Four of them had significant negative correlations (P < 0.0001).

The Chinese version of PDQ-39 is a reliable and valid instrument for Chinese PD patients. It is recommended as the most appropriate
HRQL tool for PD.