Streptococcus pyogenes upper respiratory infection and atopic conditions other than asthma: a retrospective cohort study

Background: Patients with asthma have an increased risk of Streptococcus pyogenes infection compared with those without asthma. It is unknown whether this is true for children with other atopic conditions such as atopic dermatitis or allergic rhinitis. Aims: To determine the risk of developing S. pyogenes infections of the upper respiratory tract in children and adolescents with atopic dermatitis and/or allergic rhinitis. Methods: We conducted a retrospective cohort study that followed a convenience sample of 340 healthy children. Atopic dermatitis or eczema and allergic rhinitis or hay fever were determined based on a physician diagnosis documented in medical records. All laboratory test results of cultures, rapid antigen detection, and polymerase chain reaction tests for S. pyogenes infections during the first 18 years of life were collected to compare the incidence of S. pyogenes infections between children with and without a physician diagnosis of atopic conditions. A Poisson regression was fit to determine the association between asthma and S. pyogenes infections, controlling for other covariates including asthma. Results: Of the 340 subjects, 327 were eligible for the study. Of these 327 subjects, 143 (44%) had atopic conditions other than asthma. The incidence of S. pyogenes infections in children with atopic conditions other than asthma and those without atopic conditions was 0.24 per person-year and 0.18 per person-year, respectively. The adjusted risk ratios for allergic rhinitis and atopic dermatitis were 1.36 (95% CI 1.07 to 1.66, p=0.011) and 1.30 (95% CI 0.98 to 1.71, p=0.06), respectively, controlling for asthma and other covariates. Conclusions: In addition to asthma, allergic rhinitis but not atopic dermatitis is associated with an increased risk of S. pyogenes upper respiratory tract infections. (C) 2012 Primary Care Respiratory Society UK. All rights reserved. YJ Juhn et al. Prim Care Respir J 2012; 21(2): 153-158 http://dx.doi.org/10.4104/pcrj.2011.00110