2261: Palindromic Rheumatism and Predictors of Progression to Rheumatoid Arthritis: Experience from a Tertiary Care Center in Northern India

Background/Purpose: Palindromic Rheumatism (PR) is recognized as a clinical syndrome of intermittent episodes of pain, swelling, and erythema in and around joints, which are severe and unpredictable. It has been historically associated with Rheumatoid Arthritis (RA), with many considering PR as a pre-RA stage. We conducted the first-ever study on PR in Northern India to identify the risk factors for progression to RA.

Methods: Electronic medical record data were collected from the Rheumatology clinic at our tertiary care hospital. Thirty patients were identified as having PR. Patients having a history or examination findings consistent with synovial swelling that returned to normal in between episodes without any alternative diagnosis, as determined by a rheumatologist, were included in the study. History, examination findings, and all available laboratory data were collected. Comparisons were made between the group that remained stable as PR and the group that progressed to RA according to the ACR/EULAR 2010 criteria. Comparisons were made using a t-test or chi-squared test, as per data type. Multivariate logistic regression was performed on the significant risk factors. Data were analyzed using STATA version 14 (StataCorp, College Station, TX, USA).

Results: Out of 30 patients, 16 (53.3%) remained as PR and 14 (46.7%) progressed to RA. One patient progressed to primary Sjögren's syndrome, with the arthritis remaining palindromic. The average duration of classification as RA from a diagnosis of PR was 48.50 months (SD-33.92). Age of onset, gender, duration of an arthritis flare, and time interval between the attacks were not different in the two groups. The total number of joints involved ever was higher in the group that progressed to RA (p-value: 0.0005; T-test). The results are tabulated in Table 1. Wrist and metacarpophalangeal joints were most frequently involved. ESR, CRP, RF, and ACCP values were recorded as elevated or normal as per laboratory cutoff values. CRP and RF positivity were significantly higher in the RA progression group, as depicted in Figure 1. The multivariate adjusted Odds Ratio for the number of joints involved was significant for the progression to RA [OR: 1.34 (1.10- 1.75)]. CRP and RF positivity were not statistically significant predictors for progression to RA in multivariate analysis. Additionally, two patients with erosions and deformity developed them after progression to RA. The acute arthritis responded to steroids in 24(80%) and to NSAIDS in 13(43%). As expected, only the patients progressing to RA required treatment with the tsDMARDs (4 out of 14).

Conclusion: In this cohort of patients with PR, approximately half progressed to RA. Raised CRP, RF positivity, and a higher number of joints involved may increase the risk of progression to RA. Being a retrospective study of a small sample size, we acknowledge its low power to capture differences in the other domains. It could also represent a difference in the progression of PR in the Indian Subcontinent as compared to studies published from elsewhere. Our study contributes to the management and follow-up of these patients and also lays the groundwork for future studies in PR.