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Papers of the Week

Papers: 27 Jul 2019 - 2 Aug 2019


2019 Dec




Conditioned pain modulation as biomarker of chronic pain: a systematic review of its concurrent validity.


Fernandes C, Pidal-Miranda M, Samartin-Veiga N, Carrillo-de-la-Peña M T
Pain. 2019 Dec; 160(12):2679-2690.
PMID: 31365469.


Conditioned pain modulation (CPM) is a promising psychophysical biomarker of central pain mechanisms since it significantly discriminates patients with chronic pain from healthy controls. Nevertheless, it is unclear to what extent CPM assessed experimentally is correlated with clinical manifestations of pain. To assess the concurrent validity of CPM, we performed 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. We included 32 studies that altogether encompassed data from 1958 patients and provided 62 correlations. The majority of the results (69%) reported non-significant correlations between CPM efficiency and clinical manifestations of pain, while the remaining results showed a correlation between CPM reduction and worse clinical symptoms of pain. The modality of stimulation, the type of pain, and the stimulation site appear to be critical variables that influenced the pattern of results. Given that most of the studies were conducted with highly heterogeneous methodologies and unclear risk of bias, the findings highlight the need of future studies using standardized measures of clinical and experimental pain before considering CPM as a valid biomarker of pain. We discuss some guidelines to overcome the constraints in this promising line of research.