There is a large, unexplained variation in the frequency of childhood infections. We described incidence and risk factors of infections in early childhood.
Simple infections were captured during the first 3 years of life in the Copenhagen Prospective Studies on Asthma in Childhood 2000 birth cohort. Environmental exposures were analyzed by quasi-Poisson regression and sparse principal component analysis.
The 334 children experienced a median of 14 (range 2–43) infectious episodes at ages 0 to 3 years. The overall rate of infections was associated with the number of children in the day care (adjusted incidence rate ratio [aIRR] 1.09 [1.2–1.16]) and the m2 per child in the day care (aIRR 0.96 [0.92–0.99]). Upper respiratory infections were also associated with the number of children in the day care (aIRR 1.11 [1.03–1.20]) and the m2 per child in the day care (aIRR 0.95 [0.91–0.99]), whereas lower respiratory infections were associated with caesarean section (aIRR 1.49 [1.12–1.99]), maternal smoking (aIRR 1.66 [1.18–2.33]), older siblings (aIRR 1.54 [1.19–2.01]), and the age at entry to day care (aIRR 0.77 [0.65–0.91]). The sparse principal component analysis revealed a risk factor profile driven by tobacco exposure, social circumstances, and domestic pets, but could only be used to explain 8.4% of the infection burden.
Children experienced around 14 infections during the first 3 years of life, but incidences varied greatly. Environmental exposures only explained a small fraction of the variation, suggesting host factors as major determinants of infectious burden.
Comments
RE: Epidemiology and Risk Factors of Infection in Early Childhood
Is it purely coincidence that the risk factors found in this study (maternal smoking, older siblings, low SE status) are shared by Sudden Infant Death Syndrome? Perhaps more effort should go into researching the infection paradigm. There are many questions needing answers, e.g. why does the prone sleep risk factor only operate when the baby has an URTI? (Ponsonby A-L et al. Factors potentiating the risk of sudden infant death syndrome associated with the prone position. N Engl J Med 1993;329:377–82. doi:10.1056/NEJM199308053290601). All epidemiological risk factors for SIDS are congruent with infection (Goldwater PN. Infection: the neglected paradigm in SIDS Research. Arch Dis Child 2017;102(8):767-772. doi: 10.1136/archdischild-2016-312327), so surely this is enough to change mainstream research directions?
Professor Paul N. Goldwater,
Adelaide Medical School,
University of Adelaide.