The Role of Perceived Injustice in the Experience of Chronic Pain and Disability: Scale Development and Validation

INTRODUCTION: The primary objective of this research was to evaluate the psychometric properties of a questionnaire designed to assess perceive injustice associated with injury. METHODS: In Study 1, the 12-item Injustice Experience Questionnaire (IEQ) was administered to 226 individuals with musculoskeletal conditions. A subsample of 85 individuals were interviewed 1-year later about their ongoing symptoms and return to work status. In Study 2, the IEQ and other pain-related measures were administered on two separate occasions to 70 pain patients participating in a functional restoration rehabilitation program. RESULTS: -Study 1 Principal components analysis yielded a two-component solution with eigenvalues greater 1. Item content of the two components reflected elements of blame and irreparability of loss. In cross sectional analyses, the IEQ was significantly correlated with measures of catastrophic thinking, r = .75, P < .01, fear of movement/re-injury, r = .58, P < .01, depression, r = .66, P < .01, and pain severity, r = .54, P < .01. Cross-sectional regression analyses revealed that the IEQ, beta = .44, P < .01, and the PCS, beta = .18, P < .05, each contributed significant unique variance to the prediction of pain severity. The IEQ prospectively predicted return to work status, OR = .75, 95% CI = .58-.99, but not pain severity. RESULTS: -Study 2 Analyses supported the test re-test reliability of the IEQ, r = .90, P < .01. Treatment-related changes in the IEQ were significantly correlated with an objective index of improved physical function, r = .51, P < .01. CONCLUSIONS: The findings of these two studies support the construct validity of the IEQ and suggest that this measure might be a useful complement to psychosocial assessment of individuals with persistent pain conditions. Discussion addresses the processes through which perceived injustice might impact on disability and rehabilitation outcomes.