Early antibiotic exposure and asthma prevalence up to early adulthood - a population-based cohort study

<bold>Background:</bold> Early exposure to antibiotics has been associated with asthma in early childhood. Whether this association persists into early adulthood is less studied. <bold>Aims and objectives:</bold> To investigate the association between exposure to antibiotics before 2 years of age and asthma up to 24 years of age. <bold>Methods:</bold> Participants from the population-based cohort BAMSE (N=4089) with information on antibiotic exposure before 2 years of age, information on asthma diagnosis at age 24 were included, participants with asthma before first antibiotics (n=121) were excluded resulting in 2950 participants. Asthma was defined as ever doctors diagnosis of asthma and asthma medication and/or asthma symptoms in the previous year. Antibiotics exposure was defined as use before 2 years of age, reported by the parents. The participants were divided into three groups: never asthma (68%), transient asthma defined as asthma in childhood and/or adolescence but not at 24 years of age (22%), and current asthma at 24 years of age (10%). <bold>Results:</bold> Exposure to antibiotics were more common in the group with transient asthma (82%) and current asthma (78%) compared to in the group with never asthma (68%), all p<0.001. After adjustment for sex, early RS infection, caesarean section delivery, parental asthma and smoking during pregnancy in a logistic regression, early exposure to antibiotics was associated with transient asthma adjusted odds ratio (aOR): 2.06, (95% confidence interval (CI): 1.63-2.59), and current asthma, aOR: 1.67 (95% CI: 1.23-2.27). <bold>Conclusion:</bold> Exposure to antibiotics in early life is associated with asthma up to adulthood, although causal inference can not be made from these observational data.