POS0018 REDUCTION OF DIFFUSE NOXIOUS INHIBITORY CONTROL IN ACTIVE INFLAMMATORY RHEUMATISM: A DEMONSTRATION OF CENTRAL SENSITISATION

Abstract

BackgroundIn rheumatoid arthritis (RA) and spondyloarthritis (Spa), persistent pain remains challenging. It is thought to result from central pain sensitisation, which can be measured by quantitative sensory testing (QST) and conditioned pain modulation (CPM).ObjectivesThe main objective of the RAPID (Rheumatism Pain Inhibitory Descending pathways) study, was to assess descending pain modulation (through CPM paradigms) in patients with RA or Spa, comparing these patients with healthy sex- and age-matched controls. The secondary objectives were the measurement pain thresholds (heat and cold) in a non-articular, non-painful area in patients and controls as a means of detecting possible widespread hyperalgesia as another index of central sensitisation in our patients.MethodsWe included 50 RA and 50 Spa patients and 100 age- and sex-matched controls. We assessed clinical disease variables for patients, together with responses to various psychological questionnaires. All participants underwent QST with the determination of heat and cold pain thresholds (HPT-CPT) and CPM. In CPM, a conditioning stimulus was applied to a foot and the non-dominant hand in a randomised sequence. Descending pain control was assessed as the change in HPT (in °C) following a conditioning stimulus: the higher the CPM effect, the more efficient the inhibitory control.ResultsHPT and CPT were similar in patients and controls. Mean CPM effect was significantly weaker in patients than controls: 0.25°C (±2.57) and 2.79°C (±2.31) for patients and controls, respectively (p<0.0001) for conditioning on the foot; 0.57°C (±2.74) and 2.68°C (±2.12) (p<0.0001), respectively, for conditioning on the hand. The heat pain threshold was 42.35°C (± 3.68°C) for patients and 41.54°C (± 3.34°C) for healthy controls; this difference was not statistically significant. The cold pain threshold was 13.11°C (± 10.04°C) for patients and 13.28°C (± 9.34°C) for healthy controls; this difference was not significant. The weaker CPM effect in patients was associated with higher pain intensity. In all participants, a weak CPM effect was associated with high Central Sensitisation Inventory score, anxiety, depression, sleep disturbance and pain catastrophising.ConclusionDiffuse noxious inhibitory control is weaker in patients with active chronic inflammatory rheumatism than in healthy subjects, supporting the hypothesis of central sensitisation.Figure 1.Disclosure of InterestsNone declared