The Pain Disability Questionnaire: a reliability and validity study.

The goal of this study was to translate and adapt The Pain Disability Questionnaire (PDQ) to Brazilian Portuguese, as well as to assess its psychometric properties and practicability. The following methodological steps were followed: translation, synthesis, back-translation, expert committee assessment and pre-test. The psychometric properties were assessed through the application of a questionnaire to 119 patients with chronic musculoskeletal disorders. The results indicated the reliability of the instrument, with a Cronbach's alpha coefficient of 0.86, and high stability in the test-retest. A moderate correlation was found between the PDQ scores and the numerical pain scale. Negative correlations were found between the Spitzer Quality of Life Index and the functional condition, psychosocial component and total PDQ score. Construct validity demonstrated significant difference in PDQ scores between symptomatic and asymptomatic individuals. The PDQ revealed fast application and easy understanding. The results indicated a successful cultural adaptation and reliable psychometric properties.