Preliminary Validation of the Injustice Experience Questionnaire in Patients With Advanced Cancer

Context When diagnosed with advanced cancer, patients may perceive their situation as an injustice. The Injustice Experience Questionnaire (IEQ) is a 12-item measure of perceived unfairness originally developed for patients with chronic pain. The factor structure, reliability, and validity of the IEQ in patients with cancer have not been assessed. Objectives To examine the factor structure, internal consistency, and construct validity of the IEQ in patients with advanced cancer. Methods Patients with advanced lung or prostate cancer (N = 201) were recruited from academic and public clinics in Indianapolis, IN. Patients completed the 12-item IEQ and other measures of psychological processes and distress. IEQ instructions were modified to focus on cancer-related perceived injustice. Confirmatory factor analysis (CFA) was used to examine the dimensionality of the measure. Internal consistency reliability and construct validity were examined. Results CFA showed that the original IEQ's 2-factor structure had an adequate fit (RMSEA = 0.07, CFI = 0.96, SRMR = 0.05). The factors included Severity/irreparability and Blame/unfairness. Internal consistency was excellent (α = 0.92, ω = 0.94). The IEQ showed significant positive associations with physical and psychological symptoms (rs = 0.20 – 0.65, Ps < 0.05). The IEQ also showed significant negative associations with quality of life and acceptance of cancer (rs=-0.51 – -0.46, Ps < 0.05). Conclusion Findings provide preliminary support for using the IEQ in patients with advanced cancer. Future research should assess the sensitivity of the IEQ to change in an interventional context.