Back pain and body posture evaluation instrument: validation of the questionnaire for Portuguese pre-adolescents

Background: Knowledge of pre-adolescents’ postural habits and back pain profiles is essential for school health teams to develop systematized intervention strategies. Objective: To perform the psychometric validation of the Back Pain and Body Posture Evaluation Instrument (BackPEI) for Portuguese pre-adolescents. Methodology: A methodological study was conducted for the instrument’s linguistic adaptation, pre-test, and psychometric evaluation. This evaluation took place in two phases, using a test-retest design to assess the instrument’s reliability. Results: A total of 115 pre-adolescents participated in the study (M = 11.5 years). Questions 2.5 and 2.3 obtained the lowest (k = 0.072) and highest (k = 0.693) levels of agreement, respectively. For ques-tion 2.23 (pain intensity), no difference was found between the test (M = 3.54; SD = 1.98) and the retest (M = 3.54; SD = 1.33; p = 0.959), with the answers showing a strong correlation (ICC = 0.719). Conclusion: The European Portuguese version of the BackPEI retained the original 21 items, with the addition of two items suggested by the experts and proved to be a reliable tool for assessing pos-tural habits and back pain in Portuguese pre-adolescents.