Fernandes C, et al. - Given the value of conditioned pain modulation (CPM) as a promising psychophysical biomarker of central pain mechanisms as it significantly discriminates patients with chronic pain from healthy controls, researchers sought to ascertain the extent to which CPM assessed experimentally is correlated with clinical manifestations of pain. They investigated the concurrent validity of CPM via conducting a systematic review of the literature reporting correlations between CPM responses and pain intensity, disability, duration, and area in patients with different chronic pain conditions. They included 32 studies encompassing data from 1,958 patients and providing 62 correlations. As per the majority of the results (69%), CPM efficiency is nonsignificantly correlated with clinical manifestations of pain, whereas the remaining results explicated a correlation between CPM reduction and worse clinical symptoms of pain. Critical variables influencing the pattern of results possibly include the modality of stimulation, the type of pain, and the stimulation site.