Injury Location and Mechanism for Complex Regional Pain Syndrome: A Nationwide Population-Based Case-Control Study in Taiwan.

BACKGROUND: Few studies have investigated the relationship between injury location, mechanism and their association with complex regional pain syndrome (CRPS). We conducted a nationwide database survey to explore this issue. METHODS: This was a population-based case-control study. Five hundred and eighty-nine patients with at least one ambulatory visit or admission with a principal diagnosis of CRPS from 2004 to 2009 were selected. For each CRPS patient, ten age- and sex-matched non-CRPS subjects were randomly selected. The odds ratios (PLoS One. 2013;8:e57205) and 95% confidence intervals (95% CIs) of risk factors for CRPS were derived from multivariate logistic regression models. RESULTS: Injury was a risk factor for CRPS (OR, 2.96; 95% CI, 2.18 to 4.02) independent of age and sex. In adjusted models, open wound on the upper limbs (OR 1.25, 95% CI 1.02 to 1.54) conferred higher CRPS risk. Injury mechanisms including nerve and spinal cord injury (OR 2.42, 95% CI 1.44 to 4.08), muscle and joint sprain and strain (OR 1.69, 95% CI 1.40 to 2.03), superficial injury (OR 1.23, 95% CI 1.00 to 1.51), and contusion (OR 1.44, 95% CI 1.20 to 1.74), but not fracture, increased the risk of CRPS. CONCLUSION: Injury in the extremities rather than the trunk is an important risk factor for CRPS. Certain injury mechanisms confer higher risk of CRPS. This nationwide study demonstrated that injury increased CRPS nearly threefold. Open wound, sprain and strain, superficial injury, contusion, and nerve and spinal cord injury are main injury mechanisms. Injury in the extremities confers a higher risk of CRPS.