Journal: Clinical Epidemiology
Authors: Kimberly M Shea 1, Timothy L Lash 2, Sussie Antonsen 3, Susan S Jick 4, Henrik T Sørensen 5
NLM Citation: Shea KM, Lash TL, Antonsen S, Jick SS, Sørensen HT. Population-based study of the association between asthma and pneumococcal disease in children. Clin Epidemiol. 2015 Jul 15;7:325-34. doi: 10.2147/CLEP.S78619. PMID: 26203278; PMCID: PMC4507794.
Abstract
Background: Although asthma has recently been established as a risk factor for pneumococcal disease (PD), few studies have specifically evaluated this association in children.
Methods: We conducted a nation-wide population-based cohort study of the effect of asthma on childhood PD among all singleton live births in Denmark from 1994 to 2007, before the introduction of the 7-valent pneumococcal conjugate vaccine. All data were abstracted from Danish medical registries. Because underlying comorbidity substantially increases the PD risk in children, standard methods were used to assess the evidence of biologic interaction between comorbidity and asthma on the risk of PD.
Results: There were 2,253 cases of childhood PD among 888,655 children born in Denmark from 1994 to 2007. The adjusted incidence rate ratio of the effect of asthma on childhood PD was 2.2 (95% confidence interval [CI]: 2.0, 2.5). Age-stratified incidence rate ratios were 2.1 (95% CI: 1.8, 2.9) in children 6 months to <24 months, 4.1 (95% CI: 3.3, 5.1) in children 24 months to <60 months, and 2.3 (95% CI: 1.6, 3.2) in children ≥60 months. Evaluation of the biologic interaction between asthma and comorbidity in older children revealed that 55% (24 months to <60 months) to 73% (≥60 months) of cases among asthma-exposed children can be accounted for by the interaction between asthma and comorbidity.
Conclusion: These results confirm that asthma is an important risk factor for PD in children and suggest that children with underlying comorbidities are more sensitive to the effect of asthma on PD than children without comorbidities.
Keywords: asthma; children; comorbidity; pneumococcal disease.
Figures
Figure 1 Biologic interaction between asthma and comorbidity on the risk of pneumococcal disease (PD), Denmark, 1994–2007.
Notes:
(A) In children 24 to <60 months: the unadjusted incidence rate of PD in children with both asthma and comorbidity was 7.5 times the rate in children with asthma alone (532 cases versus 71 cases per 100,000 child-years, respectively). After adjusting for sex, birth weight, child year of birth, and congenital malformation, 55% (95% CI: 31, 79) of PD cases in children with both asthma and comorbidity was attributable to biologic interaction.
(B) In children ≥60 months: the unadjusted incidence rate of PD in children with both asthma and comorbidity was 14 times the rate in children with asthma alone (198 cases versus 14 cases per 100,000 child-years, respectively). After adjusting for sex, birth weight, child year of birth, and congenital malformation, 73% (95% CI: 52, 93) of PD cases in children with both asthma and comorbidity was attributable to biologic interaction.
Abbreviation: CI, confidence interval.
