Finding the undiagnosed juvenile onset spondyloarthritis (jSpA) patient: does transient synovitis of the hip help? A retrospective cohort study

The well-known diagnostic delay of juvenile spondyloarthritis (jSpA) is a major clinical problem facing patients, families, and pediatricians today. We conducted a retrospective chart review and follow-up interview study to determine if a cohort of transient synovitis of the hip (TS) patients experienced recurrent episodes of chronic joint and lower back pain possibly indicative of subjects with undiagnosed juvenile spondyloarthritis (jSpA) or enthesitis-related arthritis (ERA). In this cohort study, baseline demographic and clinical information of all coded TS patients at Children’s Hospital of Los Angeles Emergency Department from 2002 to 2022 were collected. Follow-up telephone interview data was obtained on a cohort of these subjects addressing the recurrence of TS, the presence of chronic lower back pain and/or joint pain (lasting > 6 weeks), any physician follow-up for symptoms, and the possibility of a physician diagnosis such as jSpA/ERA, or related conditions. We enrolled 74 patients (40% of 184 eligible); baseline demographic and clinical features were similar to the unenrolled cohort. Twenty-four patients (32.4%) described recurrence of the initial problem of TS. Chronic lower back pain was reported in 41.7% of the recurrent transient synovitis cohort vs. 0% of the non-transient synovitis cohort ( p < 0.001). The hips emerged as the most statistically significant involved peripheral joint. A substantial number of subjects with TS recurrence revealed subsequent symptoms highly suggestive of jSpA/ERA. These findings support the need for additional research to prospectively follow TS cases with a formal rheumatologic assessment to confirm the diagnosis of jSpA or ERA.