Raftlin - a Potential Biomarker for Axial Spondyloarthritis and Psoriatic Arthritis: An Observational Study

Our aim is to evaluate serum Raftlin levels as a biomarker for diagnosing and monitoring disease activity in patients with axial spondyloarthritis (axSpA) and Psoriatic arthritis (PsA). This trial included 40 axSpA patients, 40 PsA patients, and 40 healthy participants as the control group. Disease activity was assessed with Ankylosing Spondylitis Disease Activity Score for axSpA patients and The Disease Activity Index for Psoriatic Arthritis for PsA patients. The Spondyloarthritis Research Consortium of Canada index, health assessment questionnaire-disability index, and numeric rating scale were used to evaluate the enthesitis severity, disability, and pain status of all patients. Serum Raftlin levels were determined using the ELISA method. The 3 groups had no statistical differences regarding gender, age, weight, height, BMI, educational status, and exercise habits. The axSpA group had higher Raftlin levels than the PsA and control groups, and Raftlin levels were statistically significant in predicting the likelihood of axSpA. We found no statistically significant differences between the PsA and control groups. We found no statistically significant difference in Raftlin levels in HLA-B27 positive versus HLA-B27 negative patients in both axSpA and PsA groups. Our results also did not detect any correlation of Raftlin levels with Ankylosing Spondylitis Disease Activity Score, C-reactive protein, erythrocyte sedimentation rate, health assessment questionnaire-disability index, numeric rating scale, and Spondyloarthritis Research Consortium of Canada index in axSpA patients. Receiver operating characteristic analysis determined that Raftlin level ≥ 6.31 ng/mL discriminates axSpA from normal individuals with 92.5% sensitivity, 59% specificity, and an area under the curve of 0.738. Our results demonstrate that although serum Raftlin levels are elevated in axSpA patients, Raftlin cannot be used as an alone diagnostic marker for axSpA. Furthermore, it was not found to be related to the monitoring of disease activity, the level of pain, disability, or severity of enthesitis. This study is prospectively registered at www.clinicaltrials.gov (ID: NCT05771389).