Interexaminer reliability of infrared thermography for the diagnosis of complex regional pain syndrome

Background/purpose Infrared thermography (IRT) is a useful tool for assessing skin temperature abnormalities in patients with complex regional pain syndrome (CRPS). Although determining regions of interest (ROIs) is an essential process for interpreting thermographic images, there are no validated and standardized guidelines to determine ROIs. Therefore, ROIs may be determined differently by each observer even for the same IRT images, which can result in an important issue for IRT reliability. The purpose of this study was to investigate the interexaminer reliability of IRT in patients with CRPS. Methods Infrared thermographic images of 28 patients diagnosed with CRPS were reviewed by three independent examiners. The shapes, sizes, and the detailed locations of the ROIs were determined by the investigator's own opinion based on patient history and symptoms. After maximal skin temperature of the ROI was obtained for each patient, the degree of agreement among the three examiners limbs was assessed. Results The intraclass correlation coefficient among the three independent raters was 0.865 (95% confidence interval, 0.7480.933), indicating a high degree of reliability (P<0.001). Conclusions The reliability of IRT for assessing skin temperature abnormalities in CRPS was high when the ROIs were determined based on patient history and symptoms.