Association Between Mycophenolate Mofetil Use and Subsequent Infections Among Hospitalized Patients with Systemic Lupus Erythematosus: A Nested Case-Control Study.

Introduction: The association between mycophenolate mofetil (MMF) and infection in patients with systemic lupus erythematosus (SLE) has not been clarified. This study evaluated the degree and factors in effect of MMF use on infection in patients with SLE.

Methods: A hospitalized-based observational study was conducted to collect medical records on patients with SLE during 2010-2021. A nested case-control study was performed among 3339 patients with SLE, including 1577 cases and 1762 controls by whether they developed any type of infection. The exposure of MMF use was determined within 1 year before diagnosed infection or the end of follow-up. Logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) for association between MMF and subsequent infection.

Results: MMF was significantly associated with the risk of overall infection (adjusted OR 1.90, 95% CI 1.48-2.44) and different types of infections, including bacterial infection (adjusted OR 2.07, 95% CI 1.55-2.75), viral infection (adjusted OR 1.92, 95% CI 1.23-3.01), and opportunistic infection (adjusted OR 2.13, 95% CI 1.31-3.46). The top three risks of specific types of infections were bacteremia/septicemia, urinary tract infection/pyelonephritis, and herpes zoster. Stratification analysis showed risk of overall infection increased especially in MMF users with age over 55 years, diabetes, central nervous system involvement, and thrombocytopenia. Moreover, the risk of infection increased with increasing dosage and duration of MMF use. Additionally, the combination of MMF with CYC and other immunosuppressants significantly increases the risk of infections compared to using a single one.

Conclusions: MMF use is associated with various type of infections in patients with SLE, particularly in those with longer use, older age, complications with comorbidities, and concomitant use of CYC or other immunosuppressants.