Fungal Infections in Hospitalized Patients of Systemic Lupus Erythematosus: A United States Nationwide Cohort Analysis

Introduction/objective Immunosuppressive therapy is the cornerstone of management in patients with systemic lupus erythematosus (SLE). Patients on immunosuppressive therapy are at increased risk of developing opportunistic fungal infections. We conducted this analysis to describe the epidemiology, including incidence, risk factors, and outcomes, of fungal infections in hospitalized patients with SLE in the United States. Method A retrospective cohort study was performed by analyzing the National Inpatient Sample (NIS) 2016-2020 for all patients with a discharge diagnosis of SLE and fungal infections, including histoplasmosis, pneumocystosis, cryptococcosis, aspergillosis, and blastomycosis, as a primary or secondary diagnosis via ICD-10 (International Classification of Diseases 10th Revision) codes. Frequencies, demographics, and trends were determined and compared between hospitalized patients with SLE and those without SLE. STATA version 17 was used for data analysis. A p-value of <= 0.05 was considered statistically significant. Results In hospitalized SLE patients, there were lower odds of developing fungal infections in females (odds ratio (OR): 0.63 (95% confidence interval (CI): 0.49-0.80)) and higher odds in Hispanic (OR: 1.52 (95% CI: 1.16-1.98) and Asian (OR: 1.78 (95% CI: 1.15-2.75) populations. Steroid use (OR: 1.96 (95% CI: 1.58-2.42)), concomitant HIV infection(OR: 22.39 (95% CI: 16.06-31.22)), and the presence of leukemias (OR: 3.56 (95% CI: 1.67-7.59)) and lymphomas (OR: 3.29 (95% CI: 1.78-6.09)) in hospitalized SLE patients were significant predictors of fungal infection (p < 0.01). There were differences in the incidence of fungal infections based on geographical areas in the US, with blastomycosis being more common in the Midwest. From 2016 to 2020, there was a decline in the incidence rate of hospitalization per 100,000 for non-SLE patients with fungal infections (10.7 per 100,000 hospitalizations in 2016 versus 9.6 per 100,000 hospitalizations in 2020), whereas this rate remained steady for the SLE cohort (0.1 per 100,000 hospitalizations in 2016 versus 0.2 per 100,000 hospitalizations in 2020). Conclusions Hospitalized patients with SLE are at an increased risk of developing fungal infections, and this risk is increased further in patients who are males, are on steroid therapy, and have HIV or leukemia and lymphomas. Further studies can be done to explain the increased risk of fungal infections associated with these patient characteristics.