Research published ahead of print in the Archives of Disease in Childhood reports that despite steady falls since the 1960s, death rates from childhood stroke remain significantly higher in boys than in girls.

Although stroke is popularly believed to affect only elderly adults, stroke is among the top ten causes of death among infants and children. Death rates due to stroke among elderly adults have also fallen since the 1960s.

However the causes of stroke in children are very different from those in adults. Heart disease, sickle cell disease, cancer, meningitis, chicken pox, genetic factors, and congenital abnormalities account for most of the cases.

The researchers used national data on deaths. They studied trends in death rates from stroke for infants and children in England and Wales from 1921 to 2000.

A total of 6,029 infants and children died of a stroke during this period. Almost three quarters (71 percent) of cases were of the type known as hemorrhagic stroke. This is bleeding into the brain as opposed to a stroke cause by a blockage (ischemic stroke).

The authors say that in depth analysis showed that the death rate fell sharply during the 1920s and 1930s, but rose sharply during the 1940s. This is largely as a result of changes in the coding of disease.

Rates dropped again from the late 1960s onwards, before leveling off during the 1980s and 1990s.

After the researchers specifically reviewed trends by age, they found that stroke deaths peaked during infancy (under one year of age) at 24.5 per million person years. Deaths among infants accounted for 28 percent of all childhood stroke deaths, despite this age group accounting for only 5.4 percent of the total population studied.

Rates dropped abruptly to 2.5 per million person years, between the ages of 5 and 9. They rose again to 7.5 per million person years during late adolescence (15 to 19 years).

However, boys were more likely than girls to have a fatal stroke at all time points and at all ages. Also, boys were almost 50 percent more likely to die of stroke during infancy than girls.

The authors say that the female hormone estrogen may partly explain these differences. Estrogen protects against heart disease and stroke. It surges in early infancy and then again at puberty in girls. They suggest that on the other hand, there may be genetic factors which make boys more susceptible to brain injury and damage.

However, the authors say that since the 1960s the steady general drop in childhood stroke rates cannot be put down to more widespread treatment of high blood pressure. This has had a major impact on stroke rates among adults. Instead, it is more likely to be the result of better control of a large number of indefinite contributing factors, or changes in other unknown factors.

"Mortality from childhood stroke in England and Wales, 1921-2000"
A A Mallick, V Ganesan, F J K O'Callaghan
Online First Arch Dis Child 2009;
doi 10.1136/adc.2008.156109
Archives of Disease in Childhood

Stephanie Brunner (B.A.)

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