Smoking, diabetes increase risk of heart attacks, strokes, death

They’re called “risk factors” for a reason – people with high blood pressure, diabetes, high cholesterol and/or a smoking habit are much more likely to have heart attacks, strokes and other manifestations of cardiovascular disease, including death.

A new study coming out in Thursday’s edition of the New England Journal of Medicine analyzed health data on more than 250,000 adults to confirm that those who had any of these risk factors were in greater peril than those who didn’t. The more risk factors a person had – and the more severe they were – the greater the lifetime risk of a “cardiovascular event.” This trend held for both men and women, and for both whites and blacks.

The raw data in the new study came from 18 so-called cohort studies – including the Framingham Heart Study, the Multiple Risk Factor Intervention Trial, the Coronary Artery Risk Development in Young Adults study and the Multi-Ethnic Study of Artherosclerorisis – that examined people at least once when they were around the ages of 45, 55, 65 and 75. A person was considered to have no cardiovascular risks if they met the following criteria:

• Total cholesterol was below 180 milligrams per deciliter of blood.
• Blood pressure was below 120/80 millimeters of mercury (mm Hg) without the assistance of drugs.
• Did not have diabetes.
• Did not smoke.

Those who varied from this profile could have a risk factor that was “not optimal,” “elevated” or (if conditions were severe enough) they could be classified as having one or more “major risk factors.”

The youngest people in the study benefitted the most by having a good risk profile. Among men, 45-year-olds had a 1.4% risk of having either a fatal or nonfatal cardiovascular event before reaching age 80; the corresponding risk for a 45-year-old with at least two major risk factors was 49.5%. For heart attacks alone (fatal or nonfatal), the risk was 1.7% for the healthiest men and 42% for the least healthy.

Among women, the 45-year-olds with no risk factors faced a 4.1% chance of having a fatal or nonfatal heart issue before age 80, compared with a 30.7% risk for women with at least two major risk factors. Looking specifically at heart attacks, the risk was 1.6% for the healthiest women and 21.5% for the least healthy women.

By the time people reached age 75, the advantages of having fewer risk factors were smaller. Among men, those with no risk factors had a 17.5% risk of a fatal or nonfatal cardiovascular event by age 90, while men with at least two risk factors faced a 38.5% risk. For women, the figures were 12.4% and 36.3%.

The data allowed researchers to consider the question of why blacks have a higher risk of heart problems than do whites. The study authors said that it was largely due to the fact that blacks have more risk factors – when blacks and whites had the same level of risk factors, their overall risk for cardiovascular events was “similar,” according to the study.

One of the take-home messages is that doctors (and their patients) should work harder to prevent people from developing problems like high blood pressure and diabetes in the first place instead of treating them after the fact, the researchers wrote.

A summary of the study is online here.

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