Cross-cultural adaptation, test-retest reliability, and construct validity of the Thai version of the University of Washington Pain-Related Self-Efficacy Scale.

Introduction: One psychosocial factor in the biopsychosocial model is pain-related self-efficacy, which has been shown to be a strong predictor of response to pain treatment.

Objectives: To cross-culturally adapt the University of Washington Pain-Related Self-Efficacy Scale (UW-PRSE6) into Thai and evaluate its psychometric properties.

Methods: The study was approved by the Chulalongkorn University Human Ethics Committee (COA No. 156/2018). The original UW-PRSE6 was cross-culturally adapted using the Functional Assessment of Chronic Illness Therapy translation methodology. Two hundred forty-one individuals with chronic low back pain completed the Thai version of UW-PRSE6 (T-UW-PRSE6), Thai Fear Avoidance Beliefs Questionnaire (T-FABQ), and Thai Medical Outcome Study Short-Form 36 (T-SF-36). A subset of 152 participants completed the T-UW-PRSE6 again after a 7-day interval. Cronbach's alpha and intraclass correlation coefficients were calculated to estimate internal consistency and test-retest reliability, respectively. The construct validity of the T-UW-PRSE6 was evaluated by computing Spearman correlation coefficients between the T-UW-PRSE6 score and the measures of the validity criterion variables.

Results: The T-UW-PRSE6 had good internal consistency (Cronbach's alpha = 0.85) and moderate test-retest reliability (intraclass correlation coefficient [2,1] = 0.72). The T-UW-PRSE6 was negatively correlated with the T-FABQ Work and Physical Activity subscales ( r s = -0.34 and -0.34, respectively) and positively correlated with the General Health, Physical Functioning, Role Physical, Role Emotional, Social Functioning, Bodily Pain, Vitality, and Mental Health scales of the T-SF-36 ( r s = 0.38, 0.42, 0.54, 0.51, 0.47, 0.54, 0.41, and 0.40, respectively).

Conclusion: The T-UW-PRSE6 demonstrated acceptable psychometric properties for assessing pain-related self-efficacy in individuals with chronic low back pain, making available a measure for facilitating future cross-cultural research on pain self-efficacy.