BUFFALO, N.Y. -- One quarter of non-fatal heart attacks among persons under the age of 45 in the United States can be attributed to regular cocaine use, scientists at the University at Buffalo's Toshiba Stroke Research Center have found. The study findings appear in the January issue of Circulation.
Lead author Adnan I. Qureshi, M.D., UB assistant professor of neurosurgery, and colleagues found an association between frequent cocaine use and heart attack in this age group, but not between cocaine use and stroke.
"These findings indicate that changing behavior surrounding cocaine use, through public awareness and education, may reduce the incidence of cardiovascular disease in younger persons," Qureshi said.
Previous researchers had reported cases of heart attack and stroke in persons who had used cocaine within the previous hour. Given the increase in cocaine use among young adults in the U.S., the UB researchers undertook an extensive investigation of the possible relationship. Researchers aren't sure how cocaine might increase the chances of having a nonfatal heart attack or stroke, Qureshi said. "We know that cocaine use increases the levels of the neurotransmitters norepinephrine and dopamine at nerve terminals, which in turn increases heart rate, ventricular contraction and the heart's demand for oxygen.
"Cocaine may also constrict blood vessels and increase platelet aggregation. In addition, it has been shown to accelerate arteriosclerosis in young patients. Since regular, but not infrequent, use of cocaine was associated with an increased risk in our study, our results seem to support this latter mechanism," he said.
The researchers used data from the most recent National Health and Nutrition Examination Survey (NHANES III) in their analysis. NHANES III was conducted between 1988 and 1994 by the Centers for Disease Control to estimate the prevalence of chronic disease in the U.S. population and identify factors that place persons at risk of developing chronic health problems. It involved 40,000 persons two months of age or older. For the first time since these national surveys began, participants between the ages of 18 and 59 were asked about lifetime cocaine use.
For their analysis of the association with heart attack and stroke risk, UB researchers limited their study population to the 18-45 age group, which captured all but 25 cocaine users and resulted in a study base of 10,085. The study group was divided into three "user groups:" never, infrequent, and frequent, which included anyone reporting using the drug from 10 to more than 100 times. The survey also contained data on prevalence of non-fatal stroke or heart attack.
Analysis showed that 532 persons, or about 1 in 20, 67 percent of whom were men, reported using cocaine regularly. To estimate the impact of the drug on non-fatal heart attack or stroke, the researchers calculated the percent of population-attributable risk -- the portion of disease that would be eliminated if the exposure, use of cocaine in this case, were removed.
In general, regular users of cocaine were at nearly seven times the risk of having a non-fatal heart attack than non-users, results showed. The population-attributable risk was 25 percent, indicating that in this age group, one in four non-fatal heart attacks would not have occurred if there had been no cocaine use in the group.
There was no relationship between cocaine use and non-fatal stroke.
Additional researchers on the study were M. Fareed K. Suri, M.D.; Lee R. Guterman, Ph.D., and L. Nelson Hopkins, M.D., all of the UB Department of Neurosurgery and the Toshiba Stroke Research Center.