Approximately 50% of patients with systemic lupus erythematosus (SLE) have a serious infection during their disease course, and infections are the leading causes of hospitalization and mortality in these patients. Using a Medicaid database system with billing and demographic information for more than 24 million enrollees, Feldman and colleagues (ACR 2013; Abstract 780) identified 43,351 patients with prevalent SLE who were being treated with either a corticosteroid alone or a corticosteroid plus an immunosuppressant (either azathioprine, mycophenolate mofetil, cyclophosphamide, cyclosporine, or tacrolimus).
During follow-up, the researchers identified 13,986 serious bacterial infections, including bacteremia (23%), pneumonia (38%), and cellulitis (24%). There were also 47 cases of pneumocystosis, 382 cases of herpes zoster infection, and 114 cases of influenza, all requiring hospitalization. The incidence rate for all infections was 1.2 times higher among patients with SLE who received a corticosteroid alone or a corticosteroid plus an immunosuppressant compared with those not being treated with these agents.
The incidence of viral infections was 2.4 times higher in patients with SLE who received an immunosuppressant and a corticosteroid, and 1.3 times higher with a corticosteroid alone, compared with patients who received neither treatment. Further studies are needed to evaluate the causality of these observed associations between drugs used to treat SLE and the increased risk for infection.