Pain, Perceived Injustice, and Pain Catastrophizing in Chronic Pain Patients in Ireland.

Chronic pain is a public health concern affecting 20% to 30% of the population of Western countries. Psychological risk factors can worsen chronic pain patients. Themes of perceived injustice (PI) and pain catastrophizing are related to poor clinical outcomes. Particularly, perceived injustice has not been assessed systematically in patients at their first presentation in chronic pain clinics in Ireland. This study aims to assess the Injustice Experience Questionnaire (IEQ)'s internal consistency in the Irish population, assess PI in patients attending a chronic pain clinic in Ireland using the IEQ, investigate pain catastrophizing through the Pain Catastrophizing Scale (PCS) and its relationship with IEQ scores, and explore their relationships with self-reported Numeric Pain Rating Scale. One hundred adult patients were randomly selected from those attending the clinic for the first time. Eighty completed the IEQ (mean age 49 years, ranged 22 to 90 years; 59% female). The internal consistency of the IEQ was excellent (Cronbach's alpha = 0.93). Twenty-six patients (33%) had IEQ scores classified as severe. Patients whose cause of pain was trauma or road traffic accidents were more likely to have clinically severe scores than all other causes of pain (47% vs. 23%, P = 0.03). This has clinical consequences and may have legal implications. Pain catastrophizing scores were strongly correlated with IEQ (r = 0.60, P < 0.001). The correlation between IEQ and the Numeric Pain Rating Scale was weak (r = 0.25, P = 0.048). The results suggest that the IEQ may provide an additional tool to assess psychological contributors in problematic chronic pain patients and to institute targeted therapies to improve clinical outcomes.