Al Mohamad F, Rios Rodriguez V, Haibel H, et al. Association of nociplastic and neuropathic pain components with the presence of residual symptoms in patients with axial spondyloarthritis receiving biological disease-modifying antirheumatic drugs. RMD Open 2024;10:e004009. doi: 10.1136/rmdopen-2023-004009

In this paper, the authors used the Widespread Pain Index (WPI) to identify nociplastic pain (NoP) components in patients with radiographic axial spondyloarthritis (r-axSpA). They defined patients with a WPI score between 3 and 6 as having possible NoP, while patients with a WPI score ≥7 were considered likely to have NoP. These cut-offs were derived from the 2010 ACR criteria for fibromyalgia syndrome (FMS) (1). According to these cut-offs, a possible NoP component (WPI 3–6) was detected in 32 (41%) patients and a likely component (>6) in 4 (5%) patients. However, the 2010 ACR criteria use the WPI cut-off values in conjunction with the Symptom Severity Score, which was not available in our setting. For WPI alone, the following categorization was proposed and evaluated: 0, 1–3, 4–6, and ≥7, respectively (1). Therefore, we recalculated the frequency of possible NoP, defined as a WPI of 4–6: 17/78 (22%) patients; likely NoP (WPI >6) was observed in 4/78 (5%) patients (unchanged). Thus, the corrected frequency of NoP (taking the possible and likely groups together) was 21/78 (27%).

Another possible NoP detection approach involves using the generalised pain criterion from the 2016 ACR criteria for FMS, which identifies pain in at least 4 out of 5 defined body regions, as determined using the WPI (2). According to this approach, the study population includes 16/78 (20.5%) patients with widespread pain that may indicate the presence of a NoP component.

Since the authors did not use a dichotomized WPI value for the analysis, the models and the main study results remained unchanged.