Measuring anger in patients experiencing chronic pain - A systematic review.

Anger is prevalent in chronic pain and has been associated with pain perception, disability, behavior and treatment outcome. Objectives were (1) to survey in the context of chronic pain the application (and omission) of validated anger self-report instruments, (2) to discuss the instruments found in the context of emotion theories and (3) to identify a possible instrument preference. A systematic search of textbooks and review articles was first performed on validated instruments designed to measure the cognitive, the motivational and the subjective feeling component of anger. Thereafter, a systematic review aimed at finding chronic pain studies from 2005 to 2019 reporting on these instruments. Textbooks and reviews listed 16 validated self-report anger measurement instruments. 28 papers applying four of these were identified and two new instruments were additionally detected. The State-Trait Anger Expression (STAXI) and its precursors were most commonly used. Studies on chronic low back pain patients prevailed. In conclusion, anger in chronic pain patients is reliably measurable at low cost with self-report tools. The STAXI-II qualifies best for this purpose based on its extensive validation history. The majority of instruments lack sufficient theoretical and psychometric adequacy. A more detailed exploration of the cognitive anger component in chronic pain patients in future research is recommended.