Pain, disability, and lifestyle: Patients with complex regional pain syndrome compared to chronic musculoskeletal pain-A retrospective analysis

Background: Complex regional pain syndrome (CRPS) is an orphan disease occurring as a complication after trauma. Due to its acute onset and the typical clinical presentation of the inflammatory and autonomous signs, it is an eye-catching chronic pain disease affecting also young and working people. In social media and the internet, high pain severity and the unfavourable prognosis are often empathized.

Methods: Here, we compared epidemiological, pain and lifestyle factors of 223 CPRS patients from the "ncRNAPain" cohort with 255 patients with chronic musculoskeletal pain (MSK). MSK patients were recruited at the beginning of a multimodal pain therapy programme. We searched for factors predicting pain intensity.

Results: Both chronic pain diseases affected women in middle age. Patients with MSK were more obese, drank more alcohol, and were less educated (Pearson chi-square Test or Mann-Whitney/U-Test). Both groups smoked more than healthy people in the OECD (Organization for Economic Cooperation and Development). Mann-Whitney/U-Test confirmed that CRPS patients did not have more severe pain and did not suffer more from pain-related disability than patients with MSK. CRPS patients also had less psychiatric comorbidities. Multiple linear regression analysis revealed that group assignment, depressive characteristics, body mass index, average alcohol consumption and smoking predicted higher pain ratings, while disease duration, anxiety symptoms or gender had no influence on pain intensity.

Conclusion: In summary, our study supports a more optimistic view on pain in CRPS patients in comparison to MSK and identifies lifestyle factors that might contribute to the pathophysiology like smoking and drinking. Important next steps are the identification of CRPS patients at risk for chronification or-vice versa-with protective factors for pain resolution.

Significance: This study compares complex regional pain syndrome (CRPS) and chronic musculoskeletal pain and questions previously reported pain, disability and lifestyle factors associated with CRPS.