Reducing Women’s Risk of Heart Disease
By Timothy T. Brown, PhD
Our study, which was published in a recent issue of Health Economics, used information on approximately 7,000 people ages 44 through 88 who were enrolled in the Health and Retirement Study, which interviews individuals every 2 years about their health and other issues. We used information from five waves of the survey from 1996 to 2004.
Our analysis used specialized statistical techniques to mimic the results that would be found in a randomized controlled trial. This type of research is significant because it allows researchers to uncover causal connections at a fraction of the cost of a randomized trial and in a much shorter time frame. Once these relationships are uncovered, then focused randomized trials can explore the biological details and whether outcomes vary with variation in types of treatment.
The most surprising finding in my own research was that we only found a causal effect for women and no effect for men. The physician who was part of the study suggested that this was likely due to the fact that women develop cardiovascular disease approximately 10 years later than men do. Due to the protective effect of estrogen and other factors, women tend not to develop cardiovascular disease until after the onset of menopause. Women who receive dental care at the time they are beginning to lose the protective effect of estrogen may receive greater protective effects than men of the same age, who will tend to have more advanced cardiovascular disease.
In fact, we think that if we had conducted the study on a younger group of men and women, we would have found the reverse effect: a strong effect for men and no effect for women. This is because in a younger group, men would be at an earlier stage of cardiovascular disease development, a stage when dental care may be more effective, while premenopausal women would still be experiencing the protective effect of estrogen and other factors, making dental care less important. The lesson is that randomized trials that analyze the effect of periodontal treatment on individuals with established heart disease are less likely to find any significant relationship, because it appears that such care would mainly be effective in the early stages of cardiovascular disease.
This type of research has large implications for carefully determining the association between oral and systemic health. Health economists have long studied large data sets using specialized econometric techniques and are often able to determine causal associations that often would have been entirely missed without these techniques. For example, although all individuals benefit from regular dental care, women may benefit by visiting more frequently, and by maintaining a sound hygiene regimen, including brushing at least twice a day and flossing at least once a day.
At this point we are interested in replicating our study using a younger group of individuals to determine if we find positive results only for men and not for women. We are also interested in determining the cost implications of our findings. In particular, we are interested in determining how much the cost of treating heart disease would be lowered if more individuals were covered by dental insurance.
About the Author
Timothy T. Brown, PhD
Associate Director for Research
Berkeley Center for Health Technology
Assistant Adjunct Professor of Health Economics
School of Public Health
University of California at Berkeley