Validating the Vietnamese version of wearing - Off 19 questionnaire for patients with Parkinson's disease.

Background: One of the most common complication of the progression of Parkinson's disease (PD) is the wearing off phenomenon. A validated Vietnamese version of Wearing off 19 (WO19) questionnaire is necessary to optimize the Vietnamese PD treatment.

Objectives: This study was undertaken to determine the quality attribute of the questionnaire as a tool for early detection of wearing off (WO) in Vietnamese population with PD. We also sought the relationship between the WO phenomenon and factors concerning the clinical condition and course of the disease.

Subjects And Methods: This is an observational, cross-sectional study. Patients diagnosed with PD under dopaminergic treatment came to University Medical Center Ho Chi Minh city for a regular appointment were sequentially asked to complete the Vietnamese WO19 questionnaire. A neurologist specialized in movement disorders assessed the patient and determined whether he had experienced wearing off or not. The questionnaire results were then compared to the clinical opinion of the expert which is considered the gold standard for diagnosing wearing off. The reliability of the questionnaire is evaluated by Cronbach'α and Cohen's kappa coefficient. The validity is measured by the sensitivity and the specificity of the instrument compared to the gold standard. The multivariate logistic regression analysis is used to learn the relations of associated factors and wearing off phenomenon.

Results: 98 patients with the mean age 59.12 ± 10.99 have joined our study; 58.2% are male; and the mean disease duration is 6.32 years. The Vietnamese version of the WO19 questionnaire has a good reliability (Cronbach'α = 0.778) and the agreement with the expert assessment (the diagnostic accuracy) is at a substantial level (Kappa value = 0.618). The sensitivity and specificity of the questionnaire resulted 89.28% and 71.43% respectively. The multivariate logistic regression analysis revealed a long disease duration (≥6 years) (OR: 16.96; 95% CI: 2.17-132.57;  = 0.007), a high daily levodopa dosage (≥400 mg/day) (OR: 6.31; 95% CI: 1.36-29.23;  = 0.019) and high score of MDS-UPDRS part IV (≥4) (OR: 15.36; 95% CI: 2.13-110.58;  = 0.007) were independent predictive factors for wearing off in Vietnamese PD patients.

Conclusions: Vietnamese - WO19 is a reliable and effective tool which should be used in clinical practice for early detecting PD patients with wearing off.