Concurrent Psoriatic Arthritis and Ankylosing Spondylitis in a Middle-Aged Man: A Case Report With Peripheral Joint Functional and Quality of Life Assessment

The concurrent presentation of psoriatic arthritis (PsA) and ankylosing spondylitis (AS) is rare within the spondyloarthritis spectrum, presenting unique diagnostic and therapeutic challenges due to the simultaneous involvement of axial and peripheral joints. Accurate differentiation is crucial to guide appropriate treatment strategies and optimize patient outcomes. This report describes a 38-year-old man diagnosed with concurrent PsA and AS, managed over a 12-month period with infliximab. Functional assessments included the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Health Assessment Questionnaire (HAQ) Disability Index, Visual Analog Scale (VAS) for pain, grip strength test, and EuroQol 5-Dimension (EQ-5D) Health Utility Index. Magnetic resonance imaging (MRI) was used to monitor joint inflammation at baseline and after 12 months. Following 12 months of infliximab therapy, the patient demonstrated significant improvements in disease activity, functional outcomes, and quality of life: BASDAI: 7.3 → 1.9; HAQ Disability Index: 2.6 → 0.9; VAS for pain: 8.5 → 2.0; grip strength (right/left): 16/14 kg → 22/20 kg; EQ-5D Health Utility Index: 0.45 → 0.8; and MRI findings: a marked reduction in sacroiliac inflammation with no new erosive changes. This case underscores the therapeutic efficacy of infliximab in managing overlapping PsA and AS, demonstrating improvements in disease activity, functional capacity, and quality of life. The inclusion of grip strength as an objective functional outcome measure offers novel insights into treatment response evaluation in spondyloarthropathies. Further prospective studies are warranted to validate its clinical utility and establish optimized management protocols for patients with coexisting PsA and AS.