Skip to content


Arthritis Research & Therapy

Open Access

Serious infection incidence rates in pediatric systemic lupus erythematosus according to medication use

  • Linda T Hiraki1Email author,
  • Candace H Feldman2,
  • Mary Beth Son3,
  • Jessica M Franklin2,
  • Michael A Fischer2,
  • Daniel H Solomon2,
  • Seoyoung C Kim2,
  • Wolfgang C Winkelmayer4 and
  • Karen H Costenbader2
Arthritis Research & Therapy201416(Suppl 1):A39

Published: 18 September 2014


Systemic Lupus ErythematosusIncidence RateLupus NephritisHydroxychloroquineMedication User


We investigated incidence rates of serious infections among children with systemic lupus erythematosus (SLE) and lupus nephritis (LN) enrolled in Medicaid, the US health insurance program for low-income children and parents.


We identified all children aged 5 to <18 years with SLE (≥3 ICD-9 codes of 710.0, each >30 days apart) and LN (≥2 ICD-9 codes for renal disease on/after SLE diagnosis) in the Medicaid Analytic eXtract (MAX) from 2000 to 2006. This dataset contains all outpatient and inpatient Medicaid claims for enrollees in 47 US states and the District of Columbia. Filled prescriptions were documented and patients were classified as new users of hydroxychloroquine (HCQ), 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 per 100 person-years (PY) overall and by medication subgroup. Incidence rate ratios (IRR) (95% CI) were calculated comparing CS, IS and CS+IS with HCQ alone using Poisson models, adjusted for age, sex and duration of enrollment in Medicaid.


Among the 2,403 children with SLE who were new medication users, there were 316 serious infections in 2,215 PY. Incidence rates for all serious infections requiring hospitalization varied between 10/100 PY for SLE and 25.7/100 PY for LN. Among children with SLE receiving CS alone, incidence rates of serious infections were 3.5 times higher compared with those not receiving CS or IS. Among children receiving both CS and IS, overall serious infection incidence rates were twice as high compared with children not receiving either medication (Table 1).

Table 1


Systemic lupus erythematosus

Lupus nephritis


Unadjusted IRR (95%CI)

MV-adjusteda IRR (95% CI)

Unadjusted IRR (95%CI)

MV-adjusteda IRR (95% CI)







5.25 (4.07, 6.78)

3.58 (2.79, 4.59)

2.13 (1.51, 3.01)

1.90 (1.36, 2.67)


2.58 (1.86, 3.58)

2.46 (1.80, 3.37)

1.28 (0.80, 2.05)

1.12 (0.70, 1.78)


2.90 (2.03, 4.14)

1.99 (1.41, 2.80)



NR, not reported in accordance with CMS policy. aMultivariable adjusted models included age, sex, race/ethnicity, US residential region, area-level SES, SLE severity index.


Infection remains a common complication of SLE and is associated with significant morbidity and mortality. We observed high rates of serious infections requiring hospitalization among children with SLE and LN. Those children receiving CS alone or in combination with IS had much higher rates of serious infections, compared with those children receiving HCQ alone.

Authors’ Affiliations

The Hospital for Sick Children, Toronto, Canada
Brigham and Women's Hospital, Boston, USA
Boston Children's Hospital, Boston, USA
Stanford University School of Medicine, Stanford, USA


© Hiraki et al.; licensee BioMed Central Ltd. 2014

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver ( applies to the data made available in this article, unless otherwise stated.