The increased purchase of asthma medication for individuals born preterm seems to wane with age: A register-based longitudinal national cohort study

Abstract

IntroductionPreterm birth is associated with increased risk of respiratory symptoms in childhood, often treated with asthma medication. We designed a follow-up study to previous research and investigated whether the association of gestational age with purchasing asthma medication diminishes in adulthood.MethodsWe conducted a register-based study of a national cohort of all infants born in Denmark in 1980–2009 evaluating longitudinal data on individually prescribed asthma medication (both inhaled ß-2 receptor agonist and different controller treatment over 2-year periods) available from 1995–2011. We analyzed the effect of gestational age considering age, birth year, and perinatal variables using logistic regression with a Generalized Estimating Equations model. All data were unambiguously linked through the Civil Registration System.ResultsWe included 1,819,743 individuals in our study population. We found an inverse dose-response relationship between gestational age and asthma medication in earlier age-groups with a gradual decrease in odds ratios with increasing age and loss of statistical significance in early adulthood (18–31 years). For our oldest generations, there was a significant effect of gestational age (p-value = 0.04), which became insignificant when adjusting for confounding and mediating factors (p = 0.44). There were significant interactions between gestational age and age (p<0.0001) and gestational age and birth year, but these were most important during childhood (0–11 years) and for our youngest generations (born after 1995).ConclusionThe strong association between gestational age and purchase of prescription asthma medication weakens with age into early adulthood, in consistence with the results from our previous study. The risk for purchasing medication to treat asthma-like symptoms was higher in more recent birth years, but the effect of gestational age was small beyond 11 years of age. Gestational age per se did not seem to be significant for the development of asthma-like symptoms: most of its effect could be explained by other perinatal factors.

The increased susceptibility to airway infections after preterm birth does not persist into adolescence

“…It did not find lower gestational age (GA) to be associated with higher rates of antibiotic prescription during the first year of life in children born with GA < 32 [11]. We previously found that treatment of asthma-like symptoms in childhood following preterm birth did not persist into adulthood [12,13], and hypothesized that similar a trend might be applicable for airway infections.…”

Respiratory morbidity in very low birth weight infants through childhood and adolescence

“…12,15,17 Damgaard et al 12 in a follow-up study showed a strong association between prematurity and purchase of prescribed asthma medications that weakened during adolescence. 14 The effect of gestational age was small beyond 11 years of age and gestational age per se did not seem to be significant for the development of asthma-like symptoms and most of its effect could be explained by other perinatal factors. Different results were reported by others.…”

“…The improvement in pulmonary function during childhood, and the decrease in association with birth weight or GA in some studies, 12,14 might in part be related to stricter definitions of atopic asthma and use of pulmonary function tests and allergy tests at school age, and less confounding effect of viral respiratory diseases that are common in preschool children. The impact of BPD and perinatal factors may decrease while genetic and environmental components might become more influential with time.…”

“…11 Longitudinal long-term information on the impact of being born VLBW or premature is limited. 5,9,[12][13][14][15] Brooks et al, 13 in a longitudinal study of 4 years old infants born at low birth weight (<2500 g) identified a strong independent association between low birth weight and asthma. Zhang et al, 9 using interviews of caregivers reported an increased risk for asthma at different age groups from birth to 17 years in preterm born infants.…”

Medication utilization in children born preterm in the first two years of life

“…Other studies suggest frequent use of asthma medications in childhood among former preterm infants, despite little data regarding their efficacy and safety (particularly for inhaled corticosteroids). 14 – 16 Among former preterm infants <29 weeks gestation with respiratory disease, patients from the Premature Respiratory Outcome Program cohort had increased exposure to bronchodilators and inhaled corticosteroids over the course of the first year of life, with a majority of patients receiving a prescription for at least one respiratory medication. 17 , 18 …”