Epidemiology Cohort Study

Test

Transcript

1. Exposure: Vegetarianism A Cohort Study
2. Intro and Literature Review • Many opinions and factors in “healthy” lifestyle • Diet o vegetarian (various types) o omnivores
3. Literature Review • Vegetarian diets have been associated with reduced risk of cancers o bladder o stomach o lymphatic o breast • Complicated mechanisms
4. Literature Review • Vegetarian diet is also associated with reduced risk of CVD o more established association • Reduced saturated and trans fat ingestion, sodium and cholesterol (block arteries), increased antioxidants
5. Literature Review • Some disadvantages to vegetarian o malnutrition • Theories about soy and breast cancer o estrogenic compounds • Summary o diet is complicated, studies needed to determine associations
6. Research Question Therefore.. The purpose of this study: is to estimate if there is a reduced risk of CVD disease and breast cancer associated with women aged 30-60 in British Columbia observed between 2013 and 2043 who maintain a vegetarian diet relative to a diet which also consists of meat.
7. Hypothesis Ho: There is no association between maintaining a vegetarian diet and a reduced risk for breast cancer and heart disease. Ha: There is an association between maintaining a vegetarian diet and a reduced risk for breast cancer and heart disease.
8. Study Design - Cohort
9. Question #1 This study is a ___ cohort? o a) Prospective o b) Retrospective Prospective cohort o Starts 2013 → 2043 o Disease not known while follow-up occurs
10. Question #2 This study is a ___ cohort? o a) Open cohort o b) Closed cohort o c) Fixed cohort Open cohort o Changeable characteristics o People can change their diets
11. Groups Exposed - Females, 30-60 years of age, living in British Columbia, on a vegetarian diet Unexposed - Females, 30 years of age, living in British Columbia, on an omnivorous diet
12. Measures Exposures Outcome • Questionnaires • Interviews • Diaries • Definition of vegetarian • Interviews • Clinical Confirmation • Hospital reports • Radiography, endoscopy, etc.
13. Outcome - Breast Cancer • RR = 0.55 • RR 0.55, 95% CI (0.48 - 0.65) • Interpretation: People on vegetarian diets are 41% less likely to develop breast cancer than people on non-vegetarian diets. Disease: Breast Cancer Yes No Total Exposure Vegetaria n diet 67 656 723 Non- vegetarian diet 123 611 734 Total 190 1267 1457
14. Outcome - Heart Disease • RR = 0.85 • RR 0.85, 95% CI (0.73 - 0.97) • Interpretation: People on vegetarian diets are 15 % less likely to develop heart disease than people on non-vegetarian diets. Disease: Heart Disease Yes No Total Exposure Vegetarian diet 105 509 614 Non- vegetarian diet 167 667 834 Total 272 1176 1448 Therefore, the study shows that vegetarian diet reduces the risk of developing breast cancer and heart disease.
15. BIAS Morbidity Selection Misclassification Threats to Validity
16. Threats to Validity Factors - • Diets • Exercise • Genetics • Lifestyle behaviours • Chance