Objectives To investigate whether gestational age modifies the association of airway infections that result in hospital admission during the first year after birth, with subsequent asthma risk after age 5 years.
Setting Hospital inpatients and a general population comparison group in Sweden followed for subsequent diagnoses in primary and secondary care.
Participants National registers identified 42 334 children admitted to hospital for respiratory infection in their first year after birth during 1981–1995, individually matched with 211 594 children not admitted to hospital for infection during their first year.
Primary outcome Asthma diagnoses and prescribed asthma treatments after the age of 5 years identified through registers.
Results Cox regression was used to identify a HR (and 95% CI) of 1.51 (1.47 to 1.51) for the association of respiratory infection before 1 year of age with asthma after age 5 years, after adjustment for sex, gestational age, chronic lung disease, maternal asthma and maternal smoking. When stratified by gestational age (and with additional adjustment for birth weight), there is statistically significant effect modification by gestational age, with the highest magnitude asthma risk among those born with a gestational age of less than 28 weeks, producing an adjusted HR of 2.22 (1.59 to 3.09). This higher magnitude asthma risk persisted until after age 10 years, but differences in risk by gestational age were less pronounced for asthma after age 16 years.
Conclusions Extremely preterm infants are most likely to have chronic respiratory sequelae following respiratory infections in early life.
- gestational age
- cohort study
This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.