Development of comprehensive diagnostic criteria for complex regional pain syndrome in the Japanese population.

Complex regional pain syndrome (CRPS) is a syndrome that describes a broad spectrum of sensory, motor and autonomic-like features with unproven etiology. The International Association for the Study of Pain (IASP) diagnostic criteria of CRPS shows high sensitivity but poor specificity. Using statistical-pattern-recognition methods, American researchers have suggested a new set of criteria offering acceptable sensitivity and high specificity. However, non-American CRPS patients present distinct subsets of CRPS-related signs/symptoms from those of American patients. Here, we followed a series of American studies to develop a set of CRPS diagnostic criteria that would be most suitable for the Japanese population. A standardized sign/symptom checklist was used in patient evaluations to obtain data on CRPS-related signs/symptoms in 195 participants meeting the IASP criteria. Using factor analysis, we grouped CRPS-related signs/symptoms into five distinct subgroups (trophic change, motor dysfunction, abnormal pain processing, asymmetric sudomotor activity and asymmetric edema). Discriminant function analysis of these subgroups, regarding their ability to discriminate between CRPS and non-CRPS etiology, indicated that modifying the IASP criteria could increase clinical diagnostic accuracy in the Japanese population. Our diagnostic criteria are not exactly the same as the American criteria, indicating a need for more regionally based CRPS diagnostic criteria. Different sets of CRPS diagnostic criteria could lead to dissimilar patients being diagnosed as CRPS, however, presenting problems for translation of therapeutic effects found in various studies. Therefore, we further recognize a need for a global set of common CRPS diagnostic criteria.