Recent corticosteroid use and the risk of complicated varicella in otherwise immunocompetent children
H. Patel, C. Macarthur and D. Johnson
Division of General Pediatrics, Hospital for Sick Children, University of Toronto, Ontario.
OBJECTIVE: To determine whether recent corticosteroid use was associated
with an increased risk of complicated varicella-zoster virus infection in
otherwise immunocompetent children. STUDY DESIGN: A case-control study
design was used because the outcome of interest, complicated
varicella-zoster virus infection, is rare. SETTING: Cases and controls were
selected from the population of children aged 2 months to 18 years admitted
to two hospitals, between January 1979 and July 1994 in one and between
January 1974 and July 1994 in the other, with diagnosis codes that
indicated chickenpox. POPULATION: Cases were defined as children with
invasive varicella-zoster virus infection or associated invasive bacterial
infection. Controls were defined as children with uncomplicated varicella
admitted for elective surgery, fracture or burn management, psychiatric or
social evaluation, treatment of simple dehydration, or evaluation of fever
or rash not yet diagnosed. Exclusions included varicella-zoster virus
infection in neonates and immunocompromised children. METHODS: A priori
criteria were formulated on the basis of a comprehensive literature review
to define complicated varicella-zoster virus infection. Recent
corticosteroid exposure was defined as corticosteroid use of any sort
within 30 days of onset of the chickenpox rash. Data were abstracted by
medical chart review. RESULTS: In total, 167 cases and 134 controls were
identified. Only three children (two cases and one control) had a history
of recent corticosteroid therapy. Recent corticosteroid exposure was
therefore not statistically associated with an increased risk of
complicated varicella-zoster virus infection (odds ratio, 1.6; 95%
confidence interval, 0.2 to 16.9). No differences between cases and
controls were found in sex, history of asthma, or length of hospital stay.
The mean age of cases was greater than that of controls (6.0 vs 4.7 years;
P<.01). CONCLUSIONS: Recent corticosteroid therapy in otherwise
immunocompetent children does not appear to be associated with a
statistically increased risk of complicated varicella. A conservative
estimate of risk, using the upper limit of the 95% confidence interval, is
markedly lower than previously published risk estimates.
