Infection risk associated with hypogammaglobulinemia in patients with systemic lupus erythematosus: Real-world evidence from 2014 to 2024.

OBJECTIVES

To evaluate infection risk associated with hypogammaglobulinemia in patients with systemic lupus erythematosus (SLE).

METHODS

We retrospectively analyzed 242 cases of hypogammaglobulinemia identified among 3565 hospitalized SLE patients between 2014 and 2024. Of these, 133 experienced infections, while 109 remained infection-free and served as controls.

RESULTS

Infection rates were comparable among patients with low IgG (60.0 %), IgM (56.3 %) and IgA (57.7 %) levels. Multivariate logistic regression identified low body weight, fever, medication discontinuation, lymphopenia, reduced lymphocyte count, elevated CRP levels, and decreased Th cell and NK cell counts as independent predictors of infection. During follow-up, immunoglobulin levels recovered in most patients, with rates at two years of 76.0 % for IgA, 43.8 % for IgG, and 26.2 % for IgM. Immunoglobulin normalization was associated with reduced infection risk.

CONCLUSION

Hypogammaglobulinemia increases infection risk in SLE due to multifactorial immune dysfunction. Modifiable clinical and immunologic factors, along with immunoglobulin recovery, may represent actionable targets for intervention.