Background: McGill pain questionnaire is the most useful standard tools for assessing pain. McGill pain questionnaire contains 78-word descriptive of the 20 subclasses form-ing in three main sensory, affective and evaluative domains. Due to cultural differences, the questionnaire has been translated into several languages. This study aimed to transl-ate MPQ into Persian language and assess its reliability, validity and acceptability in patients with cancer.
Methods: The study performed in Medical Oncology Department of Cancer Institute in Imam Khomeini Hospital in the Spring 2012. After translation of MPQ by two experts fluent in English, Persian version was returned to English. Then that backward transla-tion was compared with the original questionnaire and words that did not match were reviewed.  Patients with different types of cancer who suffering from chronic pain were admitted in our study. They did not receive any kind of pain killer drugs during the pre-vious 24 hours. There was no restriction of age, sex, education, type of cancer or treat-ment modality. The reliability and validity of Persian-McGill pain questionnaire after interviewing patients was assessed by test–retest reliability and internal consistency (Cronbach’s alpha).
Results: In total, 84 patients were interviewed and 30 patients who were available after 24 hour with the same condition recomplete the questionnaire. Cronbach’alpha of each domain was in 0.622-0.743 and total Crobach’s alpha (n=84) was 0.85. Evaluative aspect has only one subgroup and because of this, it is not have Crobach’s alpha. The stability coefficient (n=30) in all areas (sensory, emotional, and other domains) were 0.812-0.964. Stability coefficient among the 20 Persian McGill Pain Questionnaire (PMPQ) subclasses showed significant and reliable relationships over time for all groups.
Conclusion: This study is the first study that assessed psychometric properties and use-fulness of the MPQ in Iranian patients with cancer, showed that it is a potentially useful measure with a high validity and reliability standards.