LOS ANGELES – Hospitalizations of young people for acute ischemic stroke rose significantly over a 14-year period, with a roughly 50% increase in prevalence in the age range of 5-44 years.
However, the prevalence of stroke hospitalizations decreased significantly in older people, an analysis of data by the U.S. Centers for Disease Control and Prevention (CDC) found. Researchers studied data from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project on hospitalizations (not patients) for acute ischemic stroke from 1994 to 2007, based on hospital coding.
Dr. Mary G. George
The proportion of hospitalizations due to acute ischemic stroke increased in four of six age categories analyzed and decreased in two age groups, Dr. Mary G. George said in a press conference at the International Stroke Conference. Males aged 15-34 years tallied the biggest jump, a 53% increase, from 9.8 acute ischemic strokes per 10,000 hospitalizations in 1994-1995 to 14.8/10,000 in 2006-2007. Among females aged 15-34 years, the prevalence of ischemic stroke increased by 17%, from 3.6/10,000 to 4.2/10,000 hospitalizations.
The prevalence of acute ischemic stroke hospitalizations increased by 47% in men aged 35-44 years, from 36/10,000 hospitalizations to 52.9/10,000. The prevalence in women aged 35-44 years increased by 36%, from 21.9/10,000 to 30/10,000 hospitalizations, reported Dr. George, medical officer in the division of heart disease and stroke prevention at the CDC, Atlanta.
"Very modest" increases were seen for males and females aged 5-14 years, she said at the meeting, sponsored by the American Heart Association. The prevalence of acute ischemic stroke increased in males by 36% (from 2.8 to 3.8/10,000 hospitalizations) and by 31% in females (from 3.6 to 4.7/10,000 hospitalizations).
The study raises the unanswered question of the causes behind these increased rates of hospitalization for ischemic stroke. Risk factors for stroke became more prevalent in the time period studied because of the national obesity epidemic. It’s also possible that physicians are better at diagnosing stroke in young adults than they were before. In addition, trends in hospital billing, coding, or admitting practices may have played a role.
"We cannot link anything in particular to the trend in younger patients, but I believe the role of obesity and hypertension will prompt a big discussion. Unfortunately, right now we can’t speculate on the causes," Xin Ton, the lead investigator in the study and a health statistician at the CDC, said in a prepared statement released by the American Heart Association.
Dr. George said more research is needed into the causes behind the increased hospitalization rates for stroke, especially in young adults. "One of the things to keep in mind with this study is that we are not able to separate out trends over time in improved ability to make a diagnosis of stroke, perhaps increased referrals over this time to stroke neurologists, who might have a heightened awareness to look for stroke," she said. "Whether it is associated with increasing trends in traditional risk factors for stroke is unknown at this time," but "we clearly need to study" this possibility.
The prevalence of hospitalizations for ischemic stroke fell in females aged 0-4 years, from 0.78 to 0.38/10,000 hospitalizations, a "very modest" decrease of 51%, Dr. George said. For people older than 44 years, hospitalizations for ischemic stroke decreased by 25% for men and by 29% for women.
Among people aged 45-64 years old, rates of ischemic stroke declined from 195 to 172/10,000 hospitalizations for men and from 145 to 126/10,000 for women. Among people aged 65 or older, rates declined from 404 to 303/10,000 for men and from 379 to 274/10,000 for women.
The changes in prevalence of hospitalization for acute ischemic stroke were significant in all age groups and for both sexes except in males aged 0-4 years, who had a nonsignificant decrease from 0.6 to 0.4/10,000 hospitalizations.
Because of the methods used to identify stroke hospitalizations, "we’re fairly certain that we did not pick up all strokes in pregnancy," Dr. George added, which could affect the prevalence rates of ischemic stroke hospitalizations in the age groups containing women in their childbearing years. Separate research should examine stroke rates in pregnancy, she suggested.
The study was inspired by previous studies that suggested there may be trends toward increasing stroke in young adults, and in young women in particular, Dr. George said. The data sample represents about 20% of hospitals in an increasing number of states over time.
The investigators reported having no relevant conflicts of interest.