Prevalence and risk factors for serositis in patients with systemic lupus erythematosus: A case-control study.

Background: Systemic lupus erythematosus (SLE) is an autoimmune multisystemic disease with a wide variety of clinical manifestations. One of its symptoms, associated to high morbidity, is serositis. Its prevalence ranges between 11% and 54%, and little is known about factors associated to this manifestation. The aim of this study is to determine the prevalence of serositis in SLE patients visited at the outpatient Lupus Unit of the Hospital del Mar and identify risk factors that can be used as predictors of this manifestation.

Methods: A retrospective case-control study was performed based on the review of 297 medical records of SLE patients. Twenty-eight patients were identified to have suffered serositis (cases) and were age- and sex-matched with 2 controls with SLE without serositis.

Results: The overall prevalence of serositis in our cohort was 9.42%, being higher in men than in women, 30% versus 7.9% ( = 0.001, 95% CI: 1.7-42.4%). In 40.7%, it was the first manifestation of the disease. When looking for serositis-associated factors, an association was found with anti-dsDNA antibodies measured by the Crithidia method ( = 0.016), and different measures of corticosteroids, where cases had required higher maximum doses and more pulses than controls throughout the disease, although this last correlation was lost when adjusting for confounding variables as nephritis and arthritis. Cases also received more mycophenolic acid ( = 0.021) and, marginally, more belimumab ( = 0.056).

Conclusion: The overall prevalence of serositis was 9.42%, being significantly higher in men (30%). Therefore, male gender constitutes a risk factor for serositis, and almost one third of men will develop this manifestation, so greater awareness is required in SLE men. CrithidiaDNA+ was also identified as a risk factor, and it should be determined in all SLE patients. Cases significantly received more corticosteroid pulses and higher maximum doses in relation to other SLE severe manifestations, which could imply a more aggressive form of SLE in patients with serositis.