Suggesting that misclassification of spondyloarthritis (SpA) as rheumatoid arthritis (RA) may delay a diagnosis of SpA and therefore lead to less favorable treatment outcomes, researchers performed a meta-analysis to identify overlap and distinctions between clinical presentations of SpA and RA, particularly seronegative RA. Their report, published in Rheumatology and Therapy, supported that misclassification could be a concern, as typically SpA-related symptoms were seen in patients with RA.

Researchers retrieved studies that reported key SpA clinical presentations in patients with SpA or RA. The final review included a total of 79 studies. Fifty-four studies included both SpA and RA populations and 25 studies included seropositive and/or seronegative RA groups.

The investigators found that entheseal abnormalities were more frequent in SpA versus RA, and also in seronegative versus seropositive RA. Notably, psoriasis, nail psoriasis, and dactylitis were exclusively observed in patients with SpA. The symptoms that overlapped between the two conditions included joint inflammation and destruction, pain, diminished functional ability, and increased risk for comorbidities. The researchers also highlighted that 70 of the 79 studies had reported that advanced imaging techniques allowed for a more accurate distinction between RA and SpA. Additionally, only seven of the 54 studies directly comparing SpA and RA populations presented the conclusion that no distinction could be made.

According to lead author, Philip Mease, MD, diagnoses of patients presenting with the overlapping symptoms should consider the “availability of advanced imaging modalities,” which he suggested, “may allow for more prompt and comprehensive evaluation of peripheral manifestations in SpA and RA, reducing misclassification and delayed diagnosis.”

Source: Rheumatology and Therapy