The Shortened Version of the Profile of Mood States: A Reliable and Valid Measure of Emotional Functioning for Chronic Pain Patients

Abstract

Background: Although the Profile of Mood States has been proposed by the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT) to measure emotional functioning in chronic pain patients, it has not yet been validated in these patients. Objective: To confirm the factor structure and internal consistency of the Shortened Version of the Profile of Mood States (37 items) in patients with chronic pain. Methods: A confirmatory factor analysis (CFA) was conducted to test the theoretical structure of six factors that result in a Total Mood Disturbance episode: Tension–Anxiety (six items), Depression–Dejection (eight items), Anger–Hostility (seven items), Vigor–Activity (six items), Fatigue–Inertia (five items), and Confusion–Bewilderment (five items). Participants: A total of 588 patients with chronic pain from Spanish primary care health and community centers completed the questionnaire. Results: The factors presented adequate reliability coefficients, McDonald’s Omega (ω) between 0.77 and 0.91, and appropriate average discrimination indexes (D), ranging from 0.35 to 0.67. The Total Mood Disturbance yielded excellent results, ω = 0.95, D = 0.61. The original structure was confirmed, ECVI = 4.361 (saturated ECVI = 2.395; independent ECVI = 21.855); RMSEA = 0.070, 90% CI [0.067, 0.072]; GFI = 0.974; AGFI = 0.971; CFI = 0.853; NFI = 0.812; and NNFI = 0.843. Conclusions: The Shortened Version of the Profile of Mood States has been proven to be a valid and reliable measure of emotional functioning in chronic pain patients.