Pure peripheral spondyloarthritis, is it exceedingly rare? A real-world experience from an Indian tertiary care hospital

Abstract

Background: Peripheral spondyloarthritis (pSpA) is usually associated with psoriasis, inflammatory bowel disease, or preceding infection (called reactive arthritis). Pure pSpA is a clinical entity wherein there are enthesitis, dactylitis, or arthritis, without any of the above-associated conditions. We aimed to describe the clinical, laboratory, radiological, and management profile of pure pSpA, among patients with pSpA presenting to the rheumatology outpatient department. Materials and Methods: In this retrospective, observational study, medical records of all the patients diagnosed as pSpA by a rheumatologist, between January 1, 2016, and December 31, 2018, were included. Among these, thirty patients qualified to be called pure pSpA, and we reported their demographic characteristics (age and sex), clinical features (onset of disease, clinical signs, and symptoms), laboratory parameters (erythrocyte sedimentation rate, hemoglobin, and C-reactive protein), radiological findings, and treatment pattern. Results: Thirty patients fulfilled the criteria for pure pSpA. The mean age (standard deviation) of the patients at onset was 32 ± 5.8 years. The mean disease duration before diagnosis was 9.7 months. Arthritis, enthesitis, and dactylitis were present in 29 (96.7%), 8 (26.7%), and 9 (30%) patients, respectively. Eighteen (60%) patients had monoarthritis, while 11/30 (36.7%) had oligoarthritis, at presentation. HLA B27 was positive in 24/30 (80%) patients. Seven patients (23.3%) had bilateral sacroiliitis on imaging and two (6.7%) had unilateral sacroiliitis. Twenty patients (66.7%) required conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs), while two (6.7%) required biological DMARDs in the form of anti-tumor necrosis factor-alpha inhibitors. Conclusion: Pure pSpA is a relatively rare clinical disease which presents with either a mono or oligoarthritis and shows good treatment response to csDMARDs.

Keywords

• dactylitis
• enthesitis
• peripheral spondyloarthritis
• pure peripheral spondyloarthritis
• undifferentiated spondyloarthritis