DURHAM. N.C. -- For years, scientists have effectively demonstrated the positive effects of biomedical research on treating specific diseases and conditions.
What had been missing, say three Duke University demographers, was a nationally representative database that could monitor the long-term benefits of biomedical research for the entire U.S. population.
But with information gleaned from National Long Term Care Surveys from 1982, 1984, 1989 and 1994, and with another survey planned for 1999, long-term changes in health, disability prevalence and survival in the U.S. elderly population can now begin to be assessed, say the three demographers in an article in the October issue of The FASEB (Federation of American Societies for Experimental Biology) Journal.
Kenneth Manton, Larry Corder and Eric Stallard of Duke say that the National Long Term Care Surveys -- longitudinal surveys of the nation's elderly population that were sponsored by the National Institute on Aging -- make it "possible to examine changes in population health due to biomedical research and clinical advances as they emerge over time and are diffused through the health service system to the national population."
For example, data from the surveys showed that the prevalence rate of chronic disability and institutionalization declined significantly -- by almost 15 percent -- for the U.S. population aged 65 and older from 1982 to 1994. Manton and associates reported those findings last March. Some of the declines, such as drops in atherosclerosis and chronic circulatory diseases like stroke and heart disease, could have been anticipated based on long-term trends, the authors said. But other declines in diseases not typically recorded in mortality statistics, such as dementia and chronic joint disorders, could not so easily be anticipated at a national level, the demographers wrote.
"Although the degree of success of U.S. biomedical research to cure or prevent specific diseases varies considerably, the general level of success has been dramatic," the authors wrote. "This is shown both at the disease-specific and global health levels by improvements in survival and function."
More specifically, recent biomedical research suggests that the systematic supplementation of food with folic acid might prevent 51,000 coronary artery disease deaths per year; that vitamin E has positive effects on heart disease, stroke, atherosclerosis, diabetes and cataracts; that exogenous estrogens reduced the prevalence of dementia in women; and that aspirin can prevent a recurrence of heart attacks and strokes.
"Just like maybe 20 years ago micro-electronics were at a turning point, we can now see the findings of research beginning to accumulate at a faster pace and promising avenues for treating certain major chronic diseases are starting to emerge," Manton said in an interview. "The proof will be in the clinical trials, and when it gets translated into the population. At least the early evidence is suggestive of some major breakthroughs on the near horizon."
"One of the difficulties always, though, is that if you're looking at changes in survival, then you're talking about a potential therapy that comes out of the lab, goes through several phases of clinical trials, then has to be disseminated to the population before you start seeing what the actual population impact will be," Manton added. "That could be a 10- or 15- year process, easily. So the lag makes analyses very difficult. You also may have many therapies used to treat one disease. And, in older people, you may have multiple diseases, which makes establishing a one-to-one relationship of a treatment to a cost savings very difficult."
Nonetheless, it is important for the scientific community to attempt to assess the general societal and economic consequences of major scientific advances, the Duke demographers wrote. "If biomedical researchers do not make, or at least significantly contribute to, these economic and public health assessments with their usual analytic rigor and concern about data quality, non-scientists will necessarily make them, possibly without the necessary scientific rigor, appropriately and specially collected data, or a clear understanding of the full range of potential population benefits, short and long term, of scientific advances."
The authors also note that the need to monitor the overall benefits of biomedical research on health is likely to only increase in the future, "as greater oversight of the investment in biomedical research is demanded in a period of tight federal budgets. In addition, such monitoring may help identify the areas of greatest need for future research and determine the appropriate levels of investment on research in those areas."
The authors do point out that "there are limits to the predictability of when certain research goals might be achieved and how they will be achieved. There is simply no way to exactly predict the outcome of individual creative processes; nevertheless, confidence can be increased about the aggregate health impact of many investigator-initiated projects and activities."