Psychometric properties of the 8-item Chronic Pain Acceptance Questionnaire (CPAQ-8) in a Swedish chronic pain cohort.

Background: Acceptance and Commitment Therapy for chronic pain has good empirical support. Pain acceptance is most often assessed with the Chronic Pain Acceptance Questionnaire (CPAQ). Recently a shorter 8-item version, the CPAQ-8, was developed.

Objectives: To further validate the CPAQ-8 in a Swedish context and to test its sensitivity to treatment effects, an as-yet unknown property of the instrument.

Methods: A total of 891 patients completed the CPAQ, along with scales for anxiety and depression (Hospital Anxiety and Depression scale), kinesiophobia (Tampa Scale for Kinesiophobia) and quality of life (Short Form-36). Confirmatory factor analyses were performed to examine the factor structure. Convergent validity was tested with Pearson's correlations. Changes over time were evaluated with paired t-test.

Results: The confirmatory factor analyses showed that the CPAQ 2-factor model had a better fit compared with the 1-factor model, both for the 8- and 20-item versions. All CPAQ-8 scales demonstrated good internal consistency (alpha ≥ 0.80). They also correlated significantly with related constructs, supporting convergent validity. The CPAQ-8 explained a large share of the total variance in CPAQ-20 and was also able to track rehabilitation changes (large effect size, d = 0.89).

Conclusion: CPAQ-8 demonstrated good psychometric properties and sensitivity to rehabilitation changes. Further research that considers other cultural contexts may lead enhance the applications of this instrument.