Although cardiovascular disease is the No. 1 killer of women, it's often hard to tell whether a woman is prone to having a heart attack or stroke.

Now Paul Ridker and associates at Brigham and Women's Hospital and Harvard Medical School have come up with a new scoring system to predict which women already at intermediate risk are most likely to have a heart attack or stroke or need coronary vascular intervention in the next 10 years. Their definition of intermediate risk is a 5 percent to 20 percent risk of a cardiovascular event within 10 years.

The National Cholesterol Education Program has recommended using the Framingham Risk Score (FRS) to decide when to initiate aggressive lipid-lowering treatment. But while this strategy has worked fairly well for men, it hasn't worked too well for women because about 20 percent of women who have a heart attack lack the usual risk factors.

Decisions using the FRS are based on age, smoking status, systolic blood pressure, and total and HDL cholesterol. The newly proposed predictor for women is named the Reynolds Risk Score (RRS), after the Donald W. Reynolds Foundation, the major financial backer of the project. The RRS adds two factors to the FRS: the blood level of C-reactive protein (CRP) and the parental history of heart attack before age 60.

The failure to include family history of premature coronary heart disease has long been recognized as a weakness of the FRS. And many previous studies have shown that elevated levels of the inflammatory marker CRP are a strong predictor of cardiovascular events.

In the present reported study, using the RRS resulted in about half the women who had been adjudged at intermediate risk by the FRS, being reclassified as being at higher risk or lower risk — and, accordingly, being reassigned either to groups devoting more or less effort to lowering their LDL cholesterol.

Thus, the RRS appears to be better than the FRS for assessing intermediate-risk women. A positive feature of the RRS is that it predicts the likelihood of all cardiovascular events, not just coronary events, as is the case with the FRS.

On the negative side, the RRS only includes premature heart disease in parents, even though studies have shown that early heart disease in a sibling is probably an even greater danger sign than early disease in a parent. In addition, the new system is no more useful than the FRS in correctly categorizing women who are at either very low or very high risk.

Moreover, both the RRS and the FRS scores are aimed at determining what is likely to happen in the next 10 years. But a 50-year-old woman, for example, has the prospect of 30 to 40 additional years of life that might be shortened by a heart attack or stroke at any time over that long period of time. Treating such a woman less aggressively because the new risk system lowers her 10-year risk score may not offer the best protective strategy over the duration of her life.

I'm not sure what practical impact the new system will have on the prevention of cardiovascular events in women. In my experience, nowadays most physicians don't use the FRS, so it's unclear how many will use the new RRS. In addition, if physicians do use the FRS, they have been foolish not to consider family history of early heart attacks when making treatment decisions.

Though the publication does not go into detail on this issue, the RRS adds a measurement of glucose control (hemoglobin A1c) to the risk prediction for women with diabetes. This added feature may prove valuable. Presently, all people with diabetes are considered to carry the highest risk of cardiovascular disease and are therefore treated most aggressively. Yet, there is evidence that the cardiovascular risks for all diabetics are not the same, and so the HbA1c may help distinguish which women (and men) with diabetes warrant the most aggressive treatment.

What should women (and men) do about the new RRS system for risk classification? Most importantly, they should obtain a complete history of cardiovascular disease in their immediate family and make sure their doctors are aware of the family history. The blood test for C-reactive protein only costs about $10 and may add useful information.

Frankly, I have some qualms about the naming and royalty rights for the RRS. First, I'm not too keen on naming the new risk score after the financial backer of the project. And second, I can't avoid some negative feelings about the fact that both Ridker and the Brigham Hospital receive some royalties whenever a CRP test is performed.