Incidence Rates Of Serious Infections and Infection Subtypes Among Pediatric Systemic Lupus Erythematosus Patients Enrolled In Medicaid, According To Medication Use

Background/Purpose: We investigated incidence rates of serious infections and infection subtypes among children with SLE enrolled in Medicaid, the U.S. health insurance program for low-income children and parents.

Methods: We identified all children aged 3 to <18 years with SLE (³3 ICD-9 codes of 710.0, each >30 days apart) in the Medicaid Analytic eXtract (MAX) from 2000-2006. This dataset contains all outpatient and inpatient Medicaid claims for enrollees in 47 U. S. states and the District of Columbia. Filled prescriptions were documented and patients were classified as ever/never users of corticosteroids (CS) and immunosuppressants (IS). We identified serious infections from hospital discharge diagnosis codes for all infections, and for specific subtypes of infections (bacterial, fungal and viral). We calculated incidence rates (IR) per 1000 person-years for number of infections ³7 days following first prescription. Incidence rate ratios (IRR) (95% CI) were calculated comparing: 1) receipt of neither CS nor IS, 2) receipt of CS alone and 3) receipt of both CS and IS. We employed Poisson models, adjusted for age, sex and duration of enrollment in Medicaid.

Results: Of the 4,068 children identified with SLE. A total of 839 serious infections occurred in 457 children during 8,854 person-years. 2.9% of the children had ³3 infections during their Medicaid enrollment. (Table) Incidence rates for all serious infections requiring hospitalization varied between 43 and 109 per 1000 children per year. Among children with SLE receiving CS alone, incidence rates were approximately twice as high for both all infections and for bacterial infections, and 5.2 times higher for viral infections, compared to those children not receiving CS or IS. Among children receiving both CS and IS, overall serious infection incidence rates were approximately 2.5 times higher, bacterial infections were 2.3 times higher, and viral infections were 7.5 times higher, compared to children not receiving either medication. Fungal infection incidence rates did not appear to be increased among users of CS or IS.

Conclusion: We observed significant variation in incidence rates of serious infections among children with SLE. Those children with SLE who were receiving CS alone or in combination with IS, had much higher rates of bacterial and viral infections, compared to those children receiving neither CS nor IS. Viral infection rates were over 5 times higher among the children receiving these mediations than among those who were not.