Pain
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Multicenter Study
A prospective, multisite, international validation of the Complex Regional Pain Syndrome Severity Score.
Clinical diagnosis of complex regional pain syndrome (CRPS) is a dichotomous (yes/no) categorization, a format necessary for clinical decision making. Such dichotomous diagnostic categories do not convey an individual's subtle gradations in the severity of the condition over time and have poor statistical power when used as an outcome measure in research. This prospective, international, multicenter study slightly modified and further evaluated the validity of the CRPS Severity Score (CSS), a continuous index of CRPS severity. ⋯ A calculated smallest real difference value revealed that a change in the CSS of ≥4.9 scale points would indicate real differences in CRPS symptomatology (with 95% confidence). Across groups, larger changes in CRPS features on the CSS over time were associated in the expected direction with greater changes in pain intensity, fatigue, social functioning, ability to engage in physical roles, and general well-being. The overall pattern of findings further supports the validity of the CSS as a measure of CRPS severity and suggests it may prove useful in clinical monitoring and outcomes research.