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.

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.

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.

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.

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.