The symptoms of heart disease are often less obvious in women than in men, and as a result, some experts have recommended changing current medical practice and using separate criteria to identify the disease and predict its progression in women. However, new findings in the "Advancing Women's Health" issue of Clinical Chemistry, the journal of AACC, suggest that sex-specific criteria do not improve the prognostic accuracy of blood tests for diagnosing heart disease.
Heart disease, formally known as cardiovascular disease (CVD), remains the leading killer in the U.S. In 2009, heart disease caused approximately 25% of deaths in both men and women, according to the Centers for Disease Control and Prevention. Furthermore, CVD is underdiagnosed, and therefore undertreated, in women compared to men. Solving this problem is more important than ever now that rates of obesity, which heightens CVD risk, are surging in young women.
A research team led by David A. Morrow, MD, of Brigham and Women's Hospital, Boston, set out to determine whether the absence of sex-specific cutpoints for assessing the prognosis of CVD is contributing to the undertreatment of women. To do this, the researchers examined the ability of a high-sensitivity cardiac troponin I (hs-cTnI) test to predict the risk of a new heart attack or death in CVD patients when different test criteria were used for each gender.
Hs-cTnI tests measure circulating concentrations of cardiac troponin, a protein that originates in the heart. If the amount of cardiac troponin in a patient's bloodstream exceeds the 99th percentile of levels found in a healthy population with an even mix of both sexes, this indicates a heart attack. Cardiac troponin levels are actually much higher in healthy men than in healthy women, but few studies have researched whether defining sex-specific 99th percentile levels improves test accuracy. Surprisingly, Morrow's team found that defining these sex-specific levels did not improve test accuracy.
The team applied 99th percentile limits for men and women that were higher and lower, respectively, than the standard overall limit. With these adjusted cutpoints, six patients out of 4,695 were reclassified as being at low risk of recurrent coronary problems after originally being classified as intermediate to high risk using the overall limit. Three of these six, all of whom were men, went on to experience a heart attack or death. None of the reclassifications benefitted women, indicating that a female-specific hs-cTnI test might not lead to improved CVD treatment for women.
"Our findings in this data set would not support the need for sex-specific cutpoints for prognosis when weighed against the potential to confuse clinicians with multiple decision limits for the same assay," concluded Morrow.
Given the importance of ensuring that CVD tests do not inadvertently put women at a disadvantage, however, this Clinical Chemistry issue also presents an evaluation of Morrow's study by Allan S. Jaffe, MD, of the Mayo Clinic, Rochester, Minn., and Fred S. Apple, PhD, of the University of Minnesota School of Medicine, Minneapolis, Minn. In their editorial, Jaffe and Apple advocate for further research using different patient populations and sampling techniques to exhaust alternative explanations for Morrow's findings before definitively dismissing sex-specific 99th percentile limits.
Materials provided by American Association for Clinical Chemistry (AACC). Note: Content may be edited for style and length.
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