Validation of the Persian Version of the Brief Pain Inventory (BPI-P) in Chronic Pain Patients

Context Chronic pain needs to be evaluated with a standard instrument. The Brief Pain Inventory (BPI) is a pain assessment tool that has been validated in many languages. Objectives The aim of the present study was to develop the Persian version of the Brief Pain Inventory (BPI-P) and also to evaluate the psychometric properties of the BPI-P in the Iranian population. Methods The BPI-P was translated from the original version of BPI using standard procedure. The Persian version of the BPI and 12-item Short-Form Health Survey (SF-12) were completed by 201 patients with chronic pain who were referred to a tertiary pain care clinic from 2013 to 2015. The performance status of the patients was evaluated by physicians using Eastern Cooperative Oncology Group performance test. Results Factor analysis of the BPI-P identified two scales: pain intensity and pain interference with life. These two factors explained 68.4% of the variance. Coefficient alpha values for BPI-P items ranging from 0.87 to 0.91 showed good internal consistency of the factors. The high intraclass correlation coefficients for the items of the questionnaire confirmed the test-retest reliability for the BPI-P. Patients with higher scores in Eastern Cooperative Oncology Group performance test reported higher levels of pain intensity and pain interference with life. Pain intensity in BPI-P correlated with physical functioning, bodily pain, mental health, and vitality of the SF-12 questionnaire, whereas pain interference was associated with general health, bodily pain, mental health, vitality, and social functioning. Conclusion The present study demonstrated that the Persian version of the BPI could be a valid and reliable instrument for pain assessment in Persian-speaking patients.