According to study data published in Annals of Rheumatic Disease, soluble biomarkers of cartilage metabolism, metabolic syndrome, and inflammation were differentially expressed in psoriatic arthritis (PsA) and osteoarthritis (OA).
Serum samples from patients with PsA and OA were obtained from the biobanks of the University of Toronto PsA Program and University Health Network Arthritis Program, respectively. Patients with OA did not have inflammatory arthritis, and healthy controls had no autoimmune conditions or family history of PsA. Serum samples for OA were obtained at the time of knee or hip joint replacement surgery; serum samples for PsA and controls were obtained at the time of a clinical laboratory assessment.
Markers of cartilage metabolism (cartilage oligomeric matrix protein [COMP] and hyaluronan), metabolic syndrome (adiponectin, adipsin, resistin, hepatocyte growth factor [HGF], insulin, and leptin), and inflammation (C-reactive protein [CRP], interleukin-1β [IL-1β], IL-6, IL-8, tumor necrosis factor alpha [TNF-α], monocyte chemoattractant protein [MCP-1], and nerve growth factor [NGF]) were measured with serum ELISA and multiplex assays. Marker levels in serum were compared across groups using the Kruskal-Wallis test; pairwise comparisons were made with the Wilcoxon rank-sum test.
Multivariate logistic regression analyses were performed to identify markers that differentiated PsA from OA. Receiver operating characteristic (ROC) curves were constructed based on multivariate models.
The discovery set comprised 77 patients with PsA, 201 with OA, and 76 healthy controls. An independent set of 73 patients with PsA and 75 patients with OA was used to validate the final multivariate model.
In both the discovery and validation sets, patients with OA were significantly older than patients with PsA (P <.0001). Of 15 total markers assessed, 12 were differentially expressed across the 3 study groups: COMP, hyaluronan, resistin, HGF, insulin, leptin, CRP, IL-6, IL-8, TNFα, MCP-1, NGF (all P <.001).
Per multivariate analyses, COMP (odds ratio [OR], 1.24; 95% CI, 1.06-1.46), resistin (OR, 1.26; 95% CI, 1.07-1.48), MCP-1 (OR, 1.28; 95% CI, 0.10-1.48), and NGF (OR <0.001; 95% CI<0.001-0.25) were found to be independently associated with PsA compared with OA.
The ROC curve constructed using the model with age, sex, and these 4 biomarkers had an area under the curve (AUC) of 0.9984, compared with an AUC of 0.8727 for the model using age and sex alone (P <.001). The validation set produced similar results.
This panel of 4 biomarkers (COMP, resistin, MCP-1, and NGF) may be able to distinguish PsA from OA, although further validation in prospective studies is necessary prior to use in clinical practice.
Chandran V, Abji F, Perruccio AV, et al. Serum-based soluble markers differentiate psoriatic arthritis from osteoarthritis [published online March 25, 2019]. Ann Rheum Dis. doi:10.1136/annrheumdis-2018-214737