Study Compares Risk of Serious Infections Between Immunosuppressive Medications for Lupus

 

A recent BWH study found no significant difference in the risk of serious infections between two commonly prescribed immunosuppressive regimens for the treatment of SLE.

Over 50 percent of patients with SLE experience serious infection during the course of their disease, a consequence of the disease itself as well as the immunosuppressive regimens used for treatment.

Candace H. Feldman, MD, ScD, and collaborators have studied the comparative risks of serious infections associated with different immunosuppressive medications in a nationwide population of lupus patients enrolled in Medicaid, the largest U.S.- based health insurance for racially and ethnically diverse, low-income individuals.

Billing claims and drug dispensing data for Medicaid beneficiaries within the 29 most populated states were analyzed for the years between 2000 and 2010. Two sets of comparisons among the most commonly prescribed medications for moderate-to-severe lupus were studied:

  1. Patients who initiated treatment with cyclophosphamide compared to those who initiated mycophenolate mofetil, and
  2. Patients who initiated treatment with mycophenolate mofetil compared to those who initiated azathioprine.

The choice of treatment with cyclophosphamide vs. mycophenolate mofetil usually arises in the management of severe lupus, particularly with renal manifestations, whereas mycophenolate mofetil and azathioprine are often used interchangeably for more moderate disease.

Dr. Feldman’s study included 674 matched pairs of mycophenolate mofetil and cyclophosphamide initiators and 1,350 matched pairs of mycophenolate mofetil and azathioprine initiators. The investigators used the statistical technique called propensity score matching to compare serious infections among patients with a similar likelihood of receiving one drug (e.g. mycophenolate mofetil) compared to the other (e.g. azathioprine).

The overall rate of serious infections (primarily bacterial) requiring hospitalization was high. There was, however, no statistically significant difference in the risk of serious infections among lupus patients receiving cyclophosphamide compared to mycophenolate mofetil, or among patients receiving mycophenolate mofetil compared to azathioprine.

The high overall rates of serious infection in this racially and ethnically diverse population of Medicaid beneficiaries with lupus highlights the importance candid discussion of this risk prior to the initiation of any immunosuppressive regimen. Based on Dr. Feldman’s findings, however, there is not a significant difference in infection risk conferred by one of the regimens of immunosuppressive medications over another.

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