Table 4 Spearman correlation of the total score of PDQ-39 and PDQ-8 questionnaires to evaluate the convergent validity in association with the baseline and disease-related characteristics in Iranian Parkinson’s disease patients (n = 114)

Age

.078

0.407

0.024

0.803

Duration of disease

0.396

<0.001*

0.342

<0.001*

UPDRS score

Part I-mental

0.572

<0.001*

0.607

<0.001*

Part II-ADL

0.653

<0.001*

0.613

<0.001*

Part III-motor

0.447

<0.001*

0.386

<0.001*

Part IV-complications

0.275

0.003*

0.288

0.002*

Total

0.635

<0.001*

0.591

<0.001*

Hoehn & Yahr stage

0.442

<0.001*

0.376

<0.001*

Schwab & England ADL scale

-0.598

<0.001*

-0.503

<0.001*

Daily levodopa dose

0.313

0.001*

0.270

0.004*

Duration of levodopa administration

0.302

0.001*

0.258

0.006*