In the last year or so, women have read with interest a number of reports on the relationship between lifestyle and disease risk.
In late summer, they learned that moderate alcohol use decreases their risk of coronary heart disease and a type of stroke. In the spring of 1987, they learned that moderate alcohol use could increase their risk of breast cancer.
They learned that smoking just a few cigarettes a day could increase their risk of coronary heart disease and stroke.
These findings were attributed to epidemiologists at Harvard Medical School in Boston. But the research could not have been done without the cooperation of more than 100,000 nurses across the country.
Every other year since 1976, these nurses have completed detailed questionnaires about their health status and such factors as diet, exercise, medication use and alcohol use. In odd-numbered years, the nurses receive letters summarizing the latest findings gleaned from their answers.
”As much as we`re here doing the work, it`s their study,” said Dr. Graham Colditz, one of the Nurses` Health Study researchers. ”Without them, we`d be nothing.”
Since its inception in 1976, the Nurses` Health Study has yielded 50 publications in scientific journals. It is the largest study ever to follow women over a number of years.
Dr. Frank Speizer launched the Nurses` Health Study to study whether oral contraceptives could increase women`s risk of breast cancer.
Nearly three-fourths of the nurses surveyed completed and returned the 1976 questionnaire, a high percentage vital in this type of study, Speizer said. Cooperation has continued at that level, he said. In fact, he said, the Nurses` Health Study can account for 96 percent of its original respondents.
When a study participant reports a major change in health status, such as a heart attack or stroke, the Harvard researchers send a nurse to check her medical records.
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After following the nurses` health status for several years after the original survey, ”we could not find a relationship between oral
contraceptives and breast cancer, except in one minor subgroup for which we do not have sufficient data,” Speizer said.
The questionnaire changes each survey year, with new questions to test new hypotheses. For example, a question about the number of moles on the nurses` left arms led to the conclusion that the presence of any moles on arms or legs double the risk of melanoma, a potentially lethal skin cancer. The 1988 questionnaire, mailed out in June, asks about phobias, which may be linked to an increased risk of coronary heart disease, Colditz said.
Eventually, Colditz said, he and his colleagues would like to branch out into biological specimens, such as blood or urine samples. Already, the nurses in 1982 were asked to send a set of toenail clippings so the Harvard researchers could analyze their selenium content. The Harvard researchers are conducting an ongoing study of the relationship between selenium, an element found in food, and breast cancer.
The National Institutes of Health is funding the Nurses` Health Study through at least 1992, but Speizer and Colditz predicted the project will extend beyond then.
”As long as we could come up with reasonable, important, testable hypotheses, we would want to continue the study,” Speizer said.