Comparison of Clinical Manifestations in Rheumatoid Arthritis vs. Spondyloarthritis: A Systematic Literature Review

Introduction Misclassification of spondyloarthritis (SpA) as rheumatoid arthritis (RA) may lead to delayed SpA diagnosis and suboptimal therapeutic outcomes. Here, we evaluate the literature on clinical manifestations in patients with SpA and RA, particularly seronegative RA, to understand the potential overlap, distinctions, and most reliable approaches to accurate diagnosis. Methods In this systematic literature review, conducted according to PRISMA guidelines, we searched key biomedical databases for English-language publications of original research articles (up to July 23, 2020) and rheumatology conference abstracts (January 1, 2018-July 31, 2020) reporting key SpA clinical presentations in patients with SpA or RA. Publications were assessed for eligibility by two independent reviewers; discrepancies were resolved by a third. Studies were evaluated for publication quality using the Downs and Black checklist. Results Of 4712 records retrieved, 79 met the inclusion criteria and were included in the analysis. Of these, 54 included study populations with SpA and RA, and 25 with seropositive and/or seronegative RA. Entheseal abnormalities were more frequently reported among patients with SpA than RA and with seronegative vs. seropositive RA. Psoriasis, nail psoriasis, and dactylitis were exclusively seen in SpA vs. RA. In most publications (70 of 79), advanced imaging techniques allowed for more accurate distinction between SpA and RA. Overlapping clinical characteristics occur in SpA and RA, including inflammation and destruction of joints, pain, diminished functional ability, and increased risk for comorbidities. However, of 54 studies comparing SpA and RA populations, only seven concluded that no distinction can be made based on the SpA manifestations and outcomes examined. Conclusions Typical SpA-related clinical symptoms and signs were observed in patients with RA, suggesting that misclassification could occur. Availability of advanced imaging modalities may allow for more prompt and comprehensive evaluation of peripheral manifestations in SpA and RA, reducing misclassification and delayed diagnosis. Plain Language Summary Spondyloarthritis (SpA) is a group of chronic, inflammatory diseases that includes axial spondyloarthritis (axSpA) and psoriatic arthritis (PsA), in addition to other peripheral forms of SpA. AxSpA primarily affects the spine and can cause chronic back pain. PsA occurs in patients with the skin condition psoriasis and patients often experience symptoms including joint pain, stiffness, and swelling. Quick and accurate diagnosis of SpA is necessary to prevent joint damage and physical limitations. Rheumatoid arthritis (RA) is characterized by pain, swelling, and stiffness in multiple joints, and delayed diagnosis and treatment can have lasting effects. However, many patients with SpA and RA who initially seek medical care often experience delayed diagnoses. This study evaluated the literature on symptoms in patients with SpA and RA, particularly patients with RA without antibodies typically associated with the disease, to understand the potential overlap, differences, and most reliable ways to accurately diagnose patients. Data from 79 records were included in the analysis, 54 of which included study populations with SpA and RA. Skin and nail psoriasis, as well as swelling of the fingers and toes, was only seen in patients with SpA. Most studies showed that enhanced imaging allowed for distinguishing between SpA and RA. This study showed that typical signs and symptoms of SpA, including inflammation and joint pain, could also be seen in patients with RA, which suggests that challenges exist for accurately identifying SpA. This highlights the importance of advanced imaging to diagnose and treat patients with SpA in a timely manner.