About seven in 10 Americans who've had heart disease or a stroke regularly take aspirin, U.S. health officials report.

Low-dose aspirin is promoted as an inexpensive, effective way to prevent cardiovascular disease. Researchers from the U.S. Centers for Disease Control and Prevention wanted to know who takes it regularly (daily or every other day) and why.

"Overall, 70.8 percent of adult respondents with existing [cardiovascular disease] reported using aspirin regularly (every day or every other day)," the researchers found.

Nearly 94 percent of regular low-dose aspirin (or baby aspirin) users with a history of heart problems said they take it for heart attack prevention.

Four out of five said they take it for stroke prevention, and 76 percent for both heart attack and stroke prevention, the study authors reported Thursday. The study was based on an analysis of data from the 2013 Behavioral Risk Factor Surveillance System. Twenty states and the District of Columbia were included in the annual telephone survey.

Very few -- just 4 percent -- of these heart patients said they took aspirin for pain relief only, reported Dr. Jing Fang and colleagues at the CDC's National Center for Chronic Disease Prevention and Health Promotion.

By state, aspirin use ranged from 72 percent of people with a history of heart problems in Mississippi to 44 percent in Missouri, the report showed.

Men, people aged 65 and older, whites and those with at least two heart-risk factors are more likely to use aspirin than other groups, according to the report, published in the July 17 issue of the CDC's Morbidity and Mortality Weekly Report.

To improve adherence to recommended heart-health guidelines, the researchers said doctors and community health-care providers should target groups reporting lower aspirin use. These include Hispanics, blacks and those without a high school diploma.

More than 17,900 adults participated in the survey, with almost 13 percent reporting a history of heart disease, stroke or both.

Besides low-dose aspirin, guidelines for managing heart risks generally recommend controlling blood pressure and cholesterol levels and not smoking.

Doctors note, however, that aspirin therapy isn't for everyone because it can upset the stomach in some people.

Low-dose aspirin is 81 milligrams.