The adaptation of a Danish version of the Pain Self-Efficacy Questionnaire: reliability and construct validity in a population of patients with fibromyalgia in Denmark.

The aim of this study was to translate, culturally adapt and evaluate the psychometric properties of the Pain Self-Efficacy Questionnaire (PSEQ) in a population of patients with fibromyalgia in Denmark. The study sample included 102 patients diagnosed with fibromyalgia referred to a specialist clinic. The PSEQ was translated and adapted to a Danish setting using a standard stepwise forward-backward translation procedure, followed by initial testing and focus group interview. Reliability was examined by analysing internal consistency and test-retest agreement. Construct validity was examined by investigating dimensionality, targeting, local independence, category functioning and differential item functioning (DIF). Reliability was high: Cronbach's alpha 0.88, test-retest correlation 0.93, intraclass correlation coefficient (ICC) 0.89 and item-total correlations 0.44-0.70. Factor analyses and item response (IRT) models indicated unidimensionality, and the PSEQ-DK was well targeted to the sample. High interitem correlation was observed between two items, indicating local dependence, and item misfit and DIF were observed for a few items. However, the overall fit of the scale to a single-factor model and IRT models supported acceptable construct validity. The PSEQ-DK showed acceptable psychometric properties and can therefore represent a reliable and valid measure for evaluating self-efficacy in patients with fibromyalgia in Denmark.

Fatigue in fibromyalgia: a conceptual model informed by patient interviews.

BACKGROUND: Fatigue is increasingly recognized as an important symptom in fibromyalgia (FM). Unknown however is how fatigue is experienced by individuals in the context of FM. We conducted qualitative research in order to better understand aspects of fatigue that might be unique to FM as well as the impact it has on patients' lives. The data obtained informed the development of a conceptual model of fatigue in FM. METHODS: Open-ended interviews were conducted with 40 individuals with FM (US [n = 20], Germany [n = 10] and France [n = 10]). Transcripts were analyzed using qualitative methods based upon grounded theory to identify key themes and concepts. RESULTS: Participants were mostly female (70%) with a mean age of 48.7 years (range: 25-79). Thirty-one individuals (i.e., 77.5%) spontaneously described experiencing tiredness/lack of energy/fatigue due to FM. Participants discussed FM fatigue as being more severe, constant/persistent and unpredictable than normal tiredness. The conceptual model depicts the key elements of fatigue in FM from a patient perspective. This includes: an overwhelming feeling of tiredness (n = 17, 42.5%), not relieved by resting/sleeping (n = 15, 37.5%), not proportional to effort exerted (n = 25, 62.5%), associated with a feeling of weakness/heaviness (n = 20, 50%), interferes with motivation (n = 22, 55%), interferes with desired activities (n = 27, 67.5%), prolongs tasks (n = 15, 37.5%), and makes it difficult to concentrate (n = 21, 52.5%), think clearly (n = 12, 30%) or remember things (n = 9, 22.5%). CONCLUSION: The majority of individuals with FM who participated in this study experience fatigue and describe it as more severe than normal tiredness.