RECENT CORTICOSTEROID USE AND THE RISK OF COMPLICATED VARICELLA IN OTHERWISE IMMUNOCOMPETENT CHILDREN

Objective: To determine whether recent corticosteroid use was associat ed with an increased risk of complicated varicella-zoster virus infect ion in otherwise immunocompetent children. Study Design: A case-contro l study design was used because the outcome of interest, complicated v aricella-zoster virus infection, is rare. Setting: Cases and controls were selected from the population of children aged 2 months to 18 year s admitted to two hospitals, between January 1979 and July 1994 in one and between January 1974 aad July 1994 in the other, with diagnosis c odes that indicated chickenpox. Population: Cases were defined as chil dren with invasive varicella-zoster virus infection or associated inva sive bacterial infection. Controls were defined as children with uncom plicated varicella admitted for elective surgery, fracture or burn man agement, psychiatric or social evaluation, treatment of simple dehydra tion, or evaluation of fever or rash not yet diagnosed. Exclusions inc luded varicella-zoster virus infection in neonates and immunocompromis ed children. Methods: A priori criteria were formulated on the basis o f a comprehensive literature review to define complicated varicella-zo ster virus infection. Recent corticosteroid exposure was defined as co rticosteroid 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 assoc iated with an increased risk of complicated varicella-zoster virus inf ection (odds ratio, 1.6; 95% confidence interval, 0.2 to 16.9). No dif ferences between cases and controls were found in sex, history of asth ma, 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 corti costeroid therapy in otherwise immunocompetent children does not appea r to be associated with a statistically increased risk of complicated varicella. A conservative estimate of risk, using the upper limit of t he 95% confidence interval, is markedly lower than previously publishe d risk estimates.