Cross-cultural Adaptation and Validation of the Quebec Back Pain Disability Scale to European Portuguese Language

Low back pain (LBP) is an extremely commonly health condition. It is a musculoskeletal complaint affecting most people at some point in their lives and the consequent health care, community, and personal costs are considerable.The clinical course of acute LBP has been described as initially favorable; however, beyond 6 weeks,only very small reductions in mean pain and disability seem to occur. According to a recent meta-analysis 6 individuals with persistent LBP are expected to have moderate levels of pain and disability. In these individuals, pain can fl uctuate over time with recurrences or exacerbations and has a major impact on their functionality. In the majority of the situations (85%), chronic LBP (CLBP) could not be assigned to a recognizable, known,specifi c pathology 15 , 16 and it is most accurately labeled as nonspecific CLBP (NSCLBP). Individuals with NSCLBP are commonly referred to physiotherapy services, 17 where reducing pain and disability are the main treatment goals and outcomes.The Quebec Back Pain Disability Scale (QBPDS) is one of the most recommended questionnaires to assess functional disability associated with LBP. It was developed as a measure of “functional disability,” which was defined by the authors as “perceived difficulty associated with simple physical activities.” It is a self-administered, 20-item questionnaire where patients are asked to rate their degree of difficulty in performing a specifi c activity from 0 (“not diffi cult at all”) to 5 (“unable to do”) in each item. The QBPDS score ranges from 0 to 100, with high values indicating higher levels of disability. The QBPDS has been extensively tested and is generally acknowledged to have good validity, reliability, and responsiveness. It has been translated and culturally adapted into different languages, including Portuguese from Brazil. However, the cultural and linguistic differences between the European Portuguese and the Brazilian Portuguese languages inhibit the use of the Brazilian version among Portuguese people. Therefore, the aim of this study was to conduct the crosscultural adaptation of the Portuguese version of the QBPDS and investigate its reliability and validity in patients with CLBP. This article is part of a larger research project aiming to validate tools with clinical relevance.