• Debbie J Bean, Malcolm H Johnson, and Robert R Kydd.
• *The Auckland Regional Pain Service (TARPS), Auckland District Health Board †Department of Psychological Medicine, The University of Auckland, Auckland, New Zealand.
• Clin J Pain. 2014 Aug 1;30(8):647-53.

ObjectiveCognitive and emotional factors are known to influence peoples' pain experiences in many conditions, including low back pain. However, in complex regional pain syndrome (CRPS), their role is unclear. This study aimed to assess the relationships between psychological factors, pain, and disability in CRPS, compared with low back pain. This could help to identify target variables for psychological treatment.Materials And MethodsA total of 88 CRPS patients and 88 low back pain patients completed measures of pain, disability, depression, anxiety, and fear of movement and reinjury (kinesiophobia). Mean scores between the 2 groups were compared, and correlations between psychological factors, pain, and disability were compared between the 2 groups. Predictors of pain and disability were assessed using multiple regression analyses.ResultsThe 2 groups had remarkably similar scores on measures of pain, disability, depression, anxiety, and kinesiophobia. In both groups, those who were more depressed, anxious, and kinesiophobic were more disabled. For the CRPS group (but not the low back pain group), pain intensity significantly correlated with distress. Multivariate analyses showed that the unique predictors of disability for the 2 groups were pain and depression, and that depression had a stronger relationship with disability for the CRPS group. For both groups, pain intensity was predicted by kinesiophobia, and anxiety was a unique predictor in the CRPS group only.DiscussionIn CRPS, disability and pain severity were more strongly associated with psychological factors than they were in low back pain. Cause and effect relationships could not be established by this cross-sectional study.

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