Evaluation of psychometric properties(reliability and validity) of the Short Form of McGill pain questionaire in Iranian orthodontic patients

Abstract

Background: Pain is a subjective response to environmental stimuli and individual factors such as age, gender, pain threshold, the intensity of the stimulus and cultural differences affect the amount of pain perceived. Orthodontic pain is pain caused by the application of orthodontic force and changes in blood flow due to compression of the periodontal ligament. The experience of pain can vary in severity (mild, moderate, severe) quality (sharp, burning, dull), duration (temporary, intermittent or permanent). The purpose of this study is to translate and retranslate the English version of the short form of McGill Pain Questionnaire, and to examine the validity and reliability of the Persian version of the short form of McGill Pain Questionnaire. Methods: This was a psychometrics exploratory study. The items of the short form of McGill Pain Questionnaire were translated into Persian. A questionnaire for measuring face validity and content validity was completed by 14 orthodontists and 10 orthodontic patients. The reliability of the research instrument was assessed using Cronbach's alpha and ICC tests. For this purpose, 40 patients referred to the orthodontic department of Tabriz Dental School completed the questionnaires two weeks apart. To calculate the construct validity, 200 patients completed the questionnaire and the results were analyzed using SPSS and AMOS softwares. Results: The English version of the short form of the McGill Pain Questionnaire was translated into Persian and then retranslated into English. After reviewing the content validity of the translated questionnaire, 2 items of the short form of McGill pain assessment questionnaire were removed. The mean content validity index and content validity ratio and impact score for the items of this questionnaire were 0/79, 0/53 and 3/29, respectively. Cronbach's alpha index was 0.85 and also the intra-class correlation coefficient (ICC) for the total questionnaire was 0.85 (with 95% confidence interval). After analyzing the construct validity, the questionnaire items were divided into three categories called “chronic pain”,” beating pain” and “sharp pain”. The mean scores of all three factors were significantly related to the time since the start of orthodontic treatment; So that with increasing duration of orthodontic treatment, the amount of pain in patients increased. The mean score of the “throbbing pain” was also significantly related to the age of the patients; As the age of the patients increased, the throbbing pain increased. Conclusion: The Persian version of the short form of McGill Pain Questionnaire has acceptable validity and reliability and is a suitable tool for measuring the pain of Iranian orthodontic patients