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MONDAY, July 28, 2003 (HealthDayNews) -- Deaths from pulmonary embolisms -- blood clots in the lungs -- have been steadily declining over the past 20 years.
A new study finds the rate fell about 30 percent between 1979 and 1998.
Nevertheless, the death rates remain consistently higher among blacks and among men, says the study appearing in the July 28 issue of the Archives of Internal Medicine.
The findings, while heartening, point up a need for more prevention, experts say.
"The encouraging news is that the death rate from pulmonary embolism is falling," says Dr. Samuel Goldhaber, director of the Venous Theomboembolism Research Group and Anticoagulation Service at Brigham and Women's Hospital in Boston. But "the death rate still is substantial, and probably we should start shifting our focus more to prevention. We still, in my opinion, have an unacceptably high death rate for pulmonary embolism."
One of the lingering problems with clotting of a lung artery, or pulmonary thromboembolism (PTE) as it is formally known, is that it often goes unrecognized by health-care practitioners. "They're one of the masqueraders," says study author Dr. Kenneth T. Horlander, a pulmonary and critical care medicine physician with Clarke-Holder Clinic in LaGrange, Ga. "Someone comes in with very nonspecific symptoms which might look like a mild myocardial infarction [heart attack] or shortness of breath, and the physician doesn't consider pulmonary embolism as a possible diagnosis. It can go untreated and then we have higher mortality."
Health-care practitioners are gaining a better awareness, Horlander concedes, helped partly by better imaging techniques such as the spiral CT scan. With this new technology, doctors can actually see the clot in the lung, as opposed to a vague, fuzzy area where a clot might be.
The other confusing issue is that no one seems to know how many people die from pulmonary embolism each year. Estimates vary from 50,000 to 100,000 people annually.
Horlander undertook this study largely to try to narrow this wide range of estimates.
They looked at almost 43 million death certificates that listed PTE as the cause of death. The death certificates were part of files compiled by the National Center for Health Statistics between 1979 and 1998. Of the total, almost 600,000, or 1.3 percent, listed PTE as the cause of death and, of those, almost 200,000 -- or about one-third -- listed PTE as the underlying cause of death. The cause of death is the immediate reason, while the underlying cause is the condition or disease that set off the chain of events that led to the death.
Based on these numbers, the study authors calculated the rate of deaths due to PTE decreased from 191 per 1 million deaths in 1979 to 94 per 1 million deaths in 1998.
The bad news is that during those 20 years, mortality rates for blacks were consistently 50 percent higher than those for whites, while those for whites were consistently 50 percent higher than those for people of other races.
Within each racial group, mortality rates were 20 percent to 30 percent higher for men than for women.
"Probably the biggest find was that black males have the highest rate of mortality of pulmonary embolism, followed by black females, then white males, then white females, then other males and other females," Horlander says. "I have never seen an illness split up so perfectly."
The study did not address why these disparities might be occurring, although Horlander speculates that how long a person waited to seek care and how people were initially treated might have a bearing on the outcomes. There also may be coding issues in how the doctor filled out the death certificate. Different racial groups also have higher rates of conditions, such as cancer or smoking, which predispose a person to clotting.
Surgery, many forms of cancer, old age, trauma, obesity and inflammatory bowel disease all appear to be risk factors for PTE, as is smoking and long plane trips.
It's also not clear why an overall decrease took place, although better preventive measures, detection and treatment along with a decrease in risk factors might be at least partially responsible.
"It's hard to say in this type of study exactly what is causing that," Horlander says. "We can speculate about the possibility of it being found earlier with better diagnosis and current treatment. Further studies to find out why mortality is decreasing would be necessary."
Better diagnosis and better treatment are only one part of the story, Goldhaber maintains. "It doesn't get at the issue that we should be preventing more of these from occurring. The other thing is that there's a lot of racial disparities and that's a very big problem. We could be doing better."
More information
For more on pulmonary embolism, visit the Mayo Clinic. Goldhaber has also written two patient-friendly documents on blood clots for the American Heart Association journal, Circulation. They are Treatment of Blood Clots and Pulmonary Embolism and Deep Vein Thrombosis.
