To translate the English version of the Pain Disability Questionnaire (PDQ) into Korean and to investigate the reliability and validity of the Korean version of the PDQ (K-PDQ) in patients suffering chronic disabling musculoskeletal disorders (CDMDs).

The English version of the PDQ was translated into Korean. Ten patients with CDMDs were randomly selected for a pilot study to assess the comprehensibility of the pre-final version. One hundred and thirty-nine patients suffering from CDMDs for more than 3 months were enrolled in this study. Follow-up questionnaires were obtained to examine the test-retest reliability. Concurrent validity was evaluated by comparing the K-PDQ with the visual analogue scale (VAS). Construct validity was evaluated by comparing the K-PDQ with the brief form of the World Health Organization quality of life assessment instrument (WHOQOL-BREF) using Pearson correlation coefficient. Reliability was assessed using the intraclass correlation coefficient (ICC), and internal consistency was determined by Cronbach's alpha.

Test-retest reliability was assessed in 70 patients, with an average time interval of 12 days. The ICC was 0.958 (p<0.001). Internal consistency reached Cronbach's alpha of 0.933 for the functional component and 0.870 for the psychosocial component. The correlation coefficient for the K-PDQ when compared with the VAS was 0.834 in the first assessment and 0.831 in the second assessment. All domains of the WHOQOL-BREF showed a significant negative correlation with the K-PDQ.

The K-PDQ is a reliable and valid instrument for measuring disability and can be used to assess disability and treatment outcomes in Korean patients with CDMD.