New Research Confirms Childhood Stroke More Common in Boys

Caroline Cassels

March 12, 2008

March 12, 2008 (New Orleans, Louisiana) — Two large studies into childhood stroke confirm earlier findings from smaller studies that stroke is more common in boys.

A large international study conducted by researchers at Indiana University School of Medicine, in Indianapolis, and recently presented at the International Stroke Conference 2008, found that boys are at greater risk of ischemic stroke regardless of stroke subtype, age, or etiology.

"Stroke is more common in boys, both in neonates and in children past the neonatal period. This is true for both arterial ischemic stroke and sinovenous thrombosis. While trauma may explain part of the male predominance [in pediatric stroke], it does not seem to explain everything," said study investigator Meredith Golomb, MD.

According to Dr. Golomb, previous studies have suggested male predominance in childhood ischemic stroke, but they were limited by small sample size and unconfirmed diagnoses.

The objective of the current study, she added, was to determine whether there was a male predominance of stroke within the International Pediatric Stroke Study (IPPS), a large, prospective multicenter, multinational study that includes 30 centers in 10 countries.

No Difference in Teens

The IPPS began in 2003 and enrolled children under the age of 19 years with a validated diagnosis, both clinical and radiographic, of either arterial ischemic stroke (AIS) or cerebral sinovenous thrombosis (CSVT) in both in- and outpatient settings.

Proportions of boys were calculated for the whole group and for subgroups defined by age, stroke subtype, and cause. Neonatal stroke was defined as stroke that occurred within the first 28 days of life.

Between January 2003 and July 2007, 1194 cases of childhood AIS or CSVT were identified. According to Dr. Golomb, there were 931 cases of AIS, 247 cases of CSVT, and 16 children who had both stroke subtypes. For the purpose of the analysis, children with both stroke types were included in the CVST group. In addition, 347 strokes occurred in the neonatal period.

The United States had 52% of pediatric stroke cases, Canada 19%, and Germany 10%.

Of the total number of strokes, 716 (60%) occurred in boys. When they divided strokes by age, 61% occurred in male neonates and 59% in males beyond neonatal age.

When researchers looked at male predominance in stroke among preteens vs teens, they did not find a statistically significant difference. However, said Dr. Golomb, the study may have been underpowered to detect a true statistically significant male predominance in this age group.

Differences Not Fully Explained by Trauma

Further, the investigators also found boys were more likely than girls to suffer either kind of stroke subtypes — AIS (59%) and CVST (65%).

When researchers looked at stroke etiology, they found 66% of cases due to acute illness were male, 70% of cases caused by head and neck trauma were in boys, and 74% of stroke cases attributed to dissection were also in boys.

However, said Dr. Golomb, when cases of head and neck trauma and dissection were excluded from the analysis, there was still a male predominance, suggesting that trauma does not fully explain the gender difference.

Dr. Golomb speculated that trauma may account for part of the difference because it may be more culturally acceptable for boys to participate in contact sports than it is for girls.

She added that she and her colleagues have also considered whether the predominance of stroke in newborn boys may be due to the fact that in general boys are larger than girls and may simply have a more difficult time being delivered.

However, at this point, "we haven't found a good overall explanation, and so we're still pretty perplexed as to why there's a clear male predominance [in pediatric stroke cases]," she said.

International Study Findings Confirmed

A second study, also recently released at the International Stroke Conference 2008, analyzed United States national data for pediatric hospital discharges and also found boys are more likely than girls to suffer childhood stroke.

Presented by Warren Lo, MD, and colleagues from Children's Hospital in Columbus, Ohio, the study also suggests there are age-related differences among children for hemorrhagic and ischemic stroke.

In this study, the researchers examined discharge diagnoses of hemorrhagic and ischemic stroke for children aged 30 days to 20 years from the Kids' Inpatient Database (KID) 2003.

The study included data on 3066 discharges for ischemic or hemorrhagic stroke. After statistical weighting, these were equivalent to 3156 discharges for ischemic and 2022 discharges for hemorrhagic stroke.

Overall, the odds ratio for a male compared with a female for all types of stroke was 1.43. By stroke subtype, the odds were 37% higher for a boy to have a hemorrhagic stroke and 50% higher for an ischemic stroke.

When the data were analyzed by sex by 5-year age groups, the investigators found that the odds for males being hospitalized with a diagnosis of stroke varied by age range.

For example, hemorrhagic and ischemic was 3.54 times more likely to occur in boys than girls aged 15 to 20 years and 1.29 times more likely in boys aged 0 to 5 years. Ischemic stroke was 2.62 times more likely to occur in boys than girls aged 16 to 20 years and 1.17 times more likely in boys than girls aged 0 to 5 years.

"These findings confirm earlier reports of a male predominance for stroke and extend those reports by identifying that the odds for being hospitalized with a diagnosis of hemorrhagic and ischemic stroke in males are greatest in the very young and adolescents. This study also identifies that hemorrhage is an important stroke subtype in children. These results have implications for children's health and warrant further investigation," said Dr. Lo.

Dr. Golomb has no financial disclosures. Dr. Lo discloses that he owns more than $10,000 but less than $50,00 of Abbot Laboratory stock.

International Stroke Conference: Abstracts 73, P298. Presented February 20, 2008.


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