Papers of the Week

The major therapeutic challenge in inflammatory rheumatic diseases is the persistence of pain despite good responses to specific therapies. Central sensitization, which can be assessed clinically by psychophysical measurements, including quantitative sensory testing (QST), is a widely proposed mechanism for chronic pain. In this systematic review, we explored the scientific literature addressing quantitative sensory testing in inflammatory rheumatic diseases. We searched Pubmed and Embase for publications up to December 2021 concerning studies on quantitative sensory testing focusing on pain thresholds, temporal summation (TS) and conditioned pain modulation (CPM), in adult patients with chronic inflammatory rheumatism (e.g. rheumatoid arthritis, spondyloarthritis, psoriatic arthritis, juvenile idiopathic arthritis). The exclusion criteria were reviews, inclusion of children and no reported pain threshold. Data quality was assessed with the National Institutes of Health (NIH) Quality Assessment tools. We identified 27 studies (18 controlled, 9 uncontrolled) including 1875 patients with inflammatory rheumatic diseases and 795 controls. A decrease in pressure pain threshold, in favor of allodynia, was found in 12 of 14 controlled studies on patients with rheumatoid arthritis and spondyloarthritis. The results of other psychophysical tests, including TS and CPM, were inconsistent due to population heterogeneity and a lack of standardization of the patients' disease duration, activity and treatment. Our review shows that pain in chronic inflammatory rheumatism is associated with pressure allodynia. However, given the heterogeneous quality and discrepant results of studies of other QST outcome measures, the hypothesis of central sensitization involvement in pain processing in these patients cannot be confirmed.