Measuring 'self': preliminary validation of a short form of the Self Experiences Questionnaire in people with chronic pain.

People with chronic pain often struggle with their sense of self and this can adversely impact their functioning and well-being. Acceptance and Commitment Therapy particularly includes a process related to this struggle with self. A measure for this process, the Self Experiences Questionnaire (SEQ), was previously developed in people with chronic pain. The aim of the current study was to validate a shorter version of the SEQ in people with chronic pain to reduce respondent burden and facilitate further research. Data from 477 participants attending an interdisciplinary pain management programme were included. Participants completed measures of treatment processes (self-as-context, pain acceptance, cognitive fusion and committed action) and outcomes (pain, pain interference, work and social adjustment and depression) at baseline and post-treatment. Confirmatory factor analysis was used for item reduction. Correlations between scores from the shorter SEQ and other process and outcome variables were calculated to examine validity. Change scores of the shorter SEQ and their correlations with changes in outcome variables were examined for responsiveness. An eight-item SEQ (SEQ-8) scale including two factors, namely Self-as-Distinction and Self-as-Observer, emerged, demonstrating good reliability (Cronbach's α = .87-.90) and validity (|r| = .14-.52). Scores from SEQ-8 significantly improved after the treatment (d = .15-21), and these improvements correlated with improvements in most outcomes. The SEQ-8 appears to be a reliable and valid measure of self. This shorter format may facilitate intensive longitudinal investigation into sense of self and functioning and well-being. [Abstract copyright: © The British Pain Society 2021.]