Relationships between psychological factors, pain, and disability in complex regional pain syndrome and low back pain.

OBJECTIVE Cognitive 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 METHODS A 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. RESULTS The 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. DISCUSSION In 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.