Researchers have developed a weighted score that may be useful in the differential diagnosis of complex regional pain syndrome (CRPS). The score is based on the “most decisive” epidemiologic data and clinical features of CRPS.
The authors compared data from 1043 patients with CRPS with data from 421 patients with non-CRPS pain. The score has shown high sensitivity and specificity and is described in the Journal of Pain.
Using medical records, investigators retrospectively analyzed epidemiologic data from patients with CRPS and patients with other types of neuropathic or chronic pain. Investigators obtained detailed medical history from the patients as well as information on the presence of clinical signs of pain. Pain intensity was assessed using the numeric rating scale (NRS).
Quality and severity of pain and adjectives patients used to describe pain were also assessed. Based on these data, the investigators calculated a CRPS prediction score (CPS) which consisted of the signs and features specific to CRPS.
Based on anamnestic data, primary contributors to CRPS pain were fractures (42%), blunt traumatic injuries excluding fractures (21%), surgery (12%), spontaneous injuries without a memorable cause/event (7%), carpal tunnel syndrome (7%), sharp traumas (5%), palmar or plantar fascial fibromatosis (3%), inflammation (1%), animal bites (1%), local infections (1%), and burns (0.4%). The overall NRS score was 5.12±2.26 for the 670 patients with CRPS and spontaneous pain sensations.
The Orlando diagnostic criteria provided the greatest sensitivity (0.847), and the Bruehl criteria provided the greatest specificity (0.943). In addition, the Budapest criteria provided the best combination of sensitivity (0.819) and specificity (0.679).
Based on the compiled data, the definition of CPS, which was comprised of negative predictors (spontaneous/uncertain CRPS causes, >1 localization, indifferent skin color and sweating, no trophic changes, no temperature difference, etc) and positive predictors (spontaneous pain sensations, pain augmentation, increased hair/nail growth and sweating, edema and swelling, tendon reflexes decreased, tremor, movement initiation disorders, etc), demonstrated the best sensitivity (0.869) and very good specificity (0.829) as well as a Youden index of 0.697.
The findings from this study may not generalize to all patients with CRPS, as patients included in this analysis were treated in a specialized outpatient center. In addition, the investigators suggest the possibility of CRPS misdiagnosis in some patients, primarily as a result of the changes in CRPS diagnostic criteria that occurred during the study.
According to the investigators, the use “of a weighted scoring system would be the most important step in improvement” of CRPS diagnostics in clinical practice.
Ott S, Maihöfner C. Signs and symptoms in 1043 patients with complex regional pain syndrome (CRPS) [published online February 1, 2018]. J Pain. doi: 10.1016/j.jpain.2018.01.004