In 1948, Caroline Bedell Thomas, M.D., launched a long-term study of health and risk factors for hypertension and heart disease. Her research strategy has proved so beneficial that the work she began continues today, and her data has led to the discovery of the connection between high cholesterol and heart disease.
A native of Ithaca, New York, Caroline Bedell graduated summa cum laude from Smith College in 1925. She did graduate work in general physiology and genetics for a year at Johns Hopkins University, and then earned her medical degree from the School of Medicine in 1930. For most of the rest of her career she maintained a strong connection to her alma mater. In 1931 she was appointed an assistant in medicine at Hopkins, where she stayed for two years conducting studies in electrocardiography. In 1933 she became a National Research Council fellow in medicine and a fellow in neuropathology at Harvard Medical School. In 1934 she married Dr. Henry M. Thomas, Jr., and returned to Hopkins as a fellow in physiology. Over the next thirty years she rose through the ranks, she was appointed instructor in medicine in 1935, assistant professor in 1941, associate professor in 1952, and she received the rank of full professor in 1970.
Dr. Thomas's wide-ranging study of medical students, now called "The Johns Hopkins Precursors Study," looked at the health of Johns Hopkins medical school students from the classes of 1948 through 1964. The study followed 1,337 students over thirty-years, to see whether physical, psychological, and other profiles from their student days would prove to be predictors of diseases they suffered in later life. Although she started her research with the intent of finding the early indicators of cardiovascular disease, the results were useful in many other ways.
Her research showed that those students who developed coronary artery disease also had high cholesterol, but that not all high cholesterolemics suffered coronaries. The heart patients were, generally, those who, as students, had reported more nervousness and depression in the face of tension, more fatigue on awakening, and lower academic standing. Meanwhile, in the cancer investigations, those who developed malignancies had, as students, been generally lower in depression, anxiety, and anger than those with the other disorders. An internist with a specialty in cardiovascular disease, Dr. Thomas believed physical disease had genetic, environmental, psychological, and physiological components. Her work in this area was influenced by Dr. Adolph Meyer, who introduced the term "psychobiology" and advocated attention to the totality of the individual.
In order to collect data on her subjects, Dr. Thomas gave her student volunteers a battery of tests, from a basic physical exam to advanced cardiovascular and metabolic tests, as well as psychological surveys. Standard exams included electrocardiograms, step stress tests, tilt-tests measuring blood pressure, and cold-pressor tests, in which students had to hold one hand in a bowls of ice for over a minute while their circulatory responses to temperature extremes were measured. Long before it was standard procedure to do so, Dr. Thomas also measured the serum cholesterol levels of the study participants. It would be years later before such data would allow researchers to make the connection between high cholesterol and heart disease.
Volunteers also had to fill out eleven pages of questions about their parents and siblings, their childhood, their relationships, and their work, play, and eating habits. There were questions about smoking; coffee, tea, and alcohol consumption; as well as fat and salt intake. Such survey detail was new at the time but proved to be valuable in the long run.
Through the use of fellow student recruiters, Dr. Thomas was able to get seventeen Johns Hopkins University School of Medicine classes to participate in the study, with a 95 percent response rate. Today the study continues—with an annual response rate of 80 percent. Valuable research data continue to be gleaned from the students—now in their 60s and 70s—who are working, primarily, as physicians, around the world. In addition, more than 130 scientific and medical manuscripts have been published from the study's data. No other study in the United States has followed people for over fifty years. As Michael Klag, M.D., professor of medicine and current director of the Precursor's Study, recently concluded, "Pick any of the current issues in cardiovascular epidemiology, and she hit them all. What she asked in 1946, we're very interested in now. She hit all the high points."
Dr. Thomas retired from Hopkins in 1985, and died after a long illness in 1997. To her colleagues, she was always known as a stern taskmaster, and a dedicated researcher. She also balanced her career with her family life, despite opposition from many who didn't approve. In the 1940s women who worked were often heavily criticized, and as a mother of three Dr. Thomas had to defend her decision frequently. When questioned by a party guest about her parenting skills, Dr. Thomas apparently replied, "Some mothers drink. I work."
Before her work on cardiac disease risk factors and health outcomes, Dr. Thomas had pioneered research in the prevention and treatment of rheumatic fever, which was one of the leading causes of death for children in the 1930s and early 1940s. She was the first physician to prove that drugs could prevent rheumatic fever in susceptible children. In 1957 her work in this area was recognized with the James D. Bruce Memorial Award of the American College of Physicians. In 1958, she received the Elizabeth Blackwell citation from the New York Infirmary, and in 1985 she was awarded the Distinguished Service Award by Johns Hopkins University School of Medicine.
