Evaluation of serum level of vitamin D in patients with palindromic rheumatism in comparison with the control group and its association with clinical characteristics and disease prognosis

Abstract

Observational studies confirmed the association between vitamin D deficiency and increased risk of rheumatoid arthritis (RA). Palindromic rheumatism (PR) is considered an at-risk phenotype for RA. The current study aimed to assess the vitamin D status in patients with PR. Materials and Methods: A total of 308 participants were enrolled in this cross-sectional study. The demographic, body mass index (BMI) and smoking history of participants were obtained by direct interview. The patients' clinical and laboratory characteristics were recorded at cohort entry. In order to reduce the heterogeneity between the studied groups, propensity score matching (PSM) analyses were performed. Matching was achieved by considering age, gender, BMI and smoking status. Results: PSM resulted in 48 PR patients and 96 matched controls. We measured serum level of 25(OH)D3 in all participants using the ELISA method. A multivariate regression analysis post PSM did not show a significant increase in the risk of PR in patients with vitamin D deficiency/insufficiency. There was no significant correlation between serum levels of 25(OH)D3 and frequency of attacks, duration of attacks, number of joints and duration of symptoms before diagnosis (P-value ≥ 0.05). 25(OH)D3 serum levels in patients whose disease has progressed to RA and has not progressed to RA were 28.7±15.9 ng/ml and 25.1±11.4 ng/ml, respectively. There was no significant difference (P=0.347).