Premature Birth Linked With Influenza Complications in Young Children

By Anne Harding

NEW YORK (Reuters Health) - Children younger than two years who were born prematurely are at increased risk of being hospitalized if they develop influenza, according to a new systematic review and meta-analysis.

The study, published online December 4 in Lancet Respiratory Medicine, is the first to identify prematurity as a risk factor for flu-related complications.

"These children should therefore be considered as a priority group for interventions aiming to prevent complications from influenza, including vaccination and antiviral medications," Dr. Kay Wang of the University of Oxford in the UK told Reuters Health by email. "However, further research is still needed to assess the risk associated with children born prematurely after different gestational periods and with premature birth in children of different ages."

Roughly one in four children who develop influenza or influenza-like illness will have complications, such as otitis media or pneumonia, Dr. Wang and her team note. Current guidelines on preventing complications related to influenza are not evidence-based and do not specifically address risk factors in children, they add.

To better understand which factors put children at risk, the investigators analyzed 27 studies including more than 14,000 children. Factors that increased the likelihood of hospitalization included neurological disorders (univariable odds ratio, 4.62), prematurity (OR, 4.33), sickle cell disease (OR, 3.46), immunosuppression (OR, 2.39), diabetes (OR, 2.34), and being younger than two years of age (OR, 2.51).

Multivariate analysis of individual patient data from four studies including 1,612 children found that, when age younger than two was included as a risk factor, children with more than one risk factor had a 74% chance of being admitted to the hospital, while the risk for children with one risk factor was 52% (p<0.0001).

However, the researchers did not find an increased risk of hospitalization for children with asthma or other reactive airway disease, or for obese children.

"Our findings provide an evidence-based definition of which children are most at risk of developing complications from influenza," Dr. Wang said. "Interventions aiming to prevent these complications, including vaccination and antiviral medications, should therefore be prioritised in these groups, particularly during seasonal influenza epidemics and influenza pandemics."

She added: "Health care professionals should emphasise to parents the importance of getting their children vaccinated against influenza, particularly if they are in a high risk group. Influenza vaccination should also be encouraged in parents and other household contacts of children in high-risk groups."

The current study is part of a research program funded by the UK National Institute for Health Research, Dr. Wang noted. "As part of this programme, we will shortly be looking for children to take part in a research study looking at whether giving antibiotics to children in high-risk groups during the early stages of an influenza-like illness can reduce the risk of developing further complications such as chest infections. We would encourage anyone who is interested in finding out more about our research to look at our study website www.archiestudy.com."

In a commentary accompanying the new study, Dr. Harish Nair of the University of Edinburgh and Dr. Marc-Alain Widdowson of the Centers for Disease Control and Prevention in Atlanta note that the results "provide some of the first data to support evidence-based decisions, including data supporting future cost-effectiveness analyses, for preventive measures against influenza-related complications."

Multiple options are available to help protect young children from these complications, they add.

"Examples include the introduction, or increasing the uptake of, influenza and PCV vaccination globally, immunisation of mothers against influenza to protect very young infants, and exploration of other vaccine types such as adjuvanted vaccines that may be more immunogenic and crossprotective against non-matched strains," Dr. Nair and Dr. Widdowson write.

"In late 2012, the US Food and Drug Administration extended the license for use of oseltamivir to children aged 2 weeks to 1 year, which paves the way for increased use of this antiviral in very young children in settings where it is available," they add. "Implementation of these options should not wait for the next influenza pandemic, but be explored now to prevent the disproportionate burden of seasonal influenza on susceptible children every year."

SOURCES: http://bit.ly/1yGtzEZ and http://bit.ly/1z04rgn Lancet Respir Med 2014.

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