SAN DIEGO – Infants born even slightly preterm or of marginally low birth weight are at significantly increased risk of being readmitted to the hospital with infection throughout childhood and adolescence, results from a large, long-term Australian study demonstrated.
“These children are a large and previously unrecognized group at increased risk of infection, who may benefit from targeted prevention,” co-lead study author David Burgner, Ph.D., a pediatric infectious diseases expert at Murdoch Children’s Research Institute in Melbourne, said in an interview in advance of the annual meeting of the Pediatric Academic Societies. “This may be particularly important in resource-limited populations, where low-birth-weight and late-preterm birth is particularly common.”
Dr. Tobias Strunk
In an effort to determine the effect of gestational age and birth weight on rehospitalization with infection, Dr. Tobias Strunk, who co-led the study with Dr. Burgner, said they retrospectively evaluated 719,311 non-Aboriginal singleton births in Western Australia from 1980-2010.
“We focused on readmission to hospital after discharge from the initial birth-related admission, so the focus was more on post neonatal infections,” said Dr. Strunk, a neonatologist with King Edward Memorial Hospital for Women and Princess Margaret Hospital for Children, which are both in Subiaco, Western Australia. “Infants were followed to the age of 18 years; that is over 6.5 million person-years of follow-up. We were therefore able to look at the risk of infection in those born very close to term and close to normal birth weight, as well as the most preterm and lowest-birth-weight infants, and to look at this risk all the way through childhood and adolescence.”
After reviewing 30 years of data the researchers observed significantly increased rates of rehospitalization with infection, even among infants born late preterm (defined as 34-36 weeks’ gestational age) and early term (defined as 37-38 weeks’ gestational age), and in those born close to normal birth weight (defined as 2.5-2.9 kg). “Although the risk was less than in the extremely preterm infants and very-low-birth-weight infants, it was still increased, right up until the age of 18 years,” said Dr. Strunk, who is also a faculty member at the University of Western Australia Centre for Research Excellence for Improving Outcomes for Preterm Infants. “In fact, for every week decrease in gestational age less than 40 weeks, there was a 10.5% increased risk in hospitalization with infection. And for every 500 g reduction in birth weight below 3 kg, there was a 19.7% increased risk.”
Rates of rehospitalization with infection were highest for the most preterm infants (defined as those less than 28 weeks’ gestational age) and those with the lowest birth weights (defined as less those weighing less than 1,000 g). Specifically, these infants faced a 13-fold increased risk of lower respiratory tract infection, an 8.5-fold increased risk of viral infection, and a 4.5-fold increased risk of invasive bacterial infection, compared with infants born at term and those born at normal birth weight.
The researchers were surprised to find that the increased risk of hospitalization with infection persisted in all groups up until age 18 years. “So overall, even in infants born near term or near normal birth weight, previously considered at low or no risk, there is an unrecognized increased risk of severe infection right through childhood and the teenage years,” Dr. Strunk said. “The risk is increased for all common types of infection, including lower respiratory tract infections, bacterial infections, and viral infections.”
The researchers acknowledged certain limitations of the study, including the fact that the researchers were unable to assess individual admissions, “so it relies on statutory data from all hospitalizations. These data are less biased by differences in health-seeking behavior and individual physician practice than emergency department visits and office visits, but the study cannot capture the total burden of infection that is managed outside hospital.” Dr. Strunk also noted that the study did not include data from Aboriginal children, “who have higher rates of infectious diseases and in whom social disadvantage contributes to poor health. The study should be repeated in other populations, where we would expect similar results. We are currently collaborating to identify datasets in resource-poor settings globally to assess the possible impact of low birth weight and prematurity on childhood infection in these populations.”
The researchers reported having no relevant financial conflicts of interest.
On Twitter @dougbrunk