Systemic lupus erythematosus comorbid with chronic spontaneous urticaria: a multicentre retrospective study

This retrospective study aims to characterise the epidemiological features of systemic lupus erythematosus (SLE) concomitant with chronic spontaneous urticaria (CSU), examines the correlation between CSU occurrence and lupus disease activity, and identifies comorbidity patterns and risk factors associated with SLE-CSU.

A total of 40 SLE patients with concomitant CSU and 160 age-matched and sex-matched SLE controls without CSU were included. The Mann-Whitney U-test was used to assess disease activity at SLE onset in both groups. A Wilcoxon signed-rank test was conducted to compare the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores before and after CSU onset in patients with SLE. χ² tests were applied to evaluate differences in SLE activity grading, clinical manifestations, laboratory findings and treatments between patients with SLE with and without CSU. In addition, univariate and multivariate logistic regression analyses were performed to identify risk factors for CSU development in patients with SLE.

Wilcoxon signed-rank tests revealed that in the SLE-CSU group, the occurrence of CSU did not result in an increase of SLEDAI scores. Univariate analysis revealed significant differences between the SLE-CSU and SLE-only groups in the presence of cylindruria, elevated IgM, IgA, IgG, serositis, mucosal ulcers and anti-Pm-Scl antibodies (p<0.05). Multivariate logistic regression analysis identified cylindruria (OR: 6.152, CI 2.352 to 16.093, p＜0.001), elevated IgA (OR: 7.598, CI 1.194 to 48.368, p=0.032), elevated IgG (OR: 3.252, CI 1.331 to 7.946, p=0.010) and mucosal ulcers (OR: 3.838, CI 1.166 to 12.637, p=0.027) as independent risk factors for CSU occurrence in patients with SLE.

The presence of CSU in patients with SLE does not necessarily indicate increased lupus activity. Rather, cylindruria, mucosal ulcers and elevated IgA and IgG levels were identified as independent risk factors for CSU in patients with SLE.