1. Ora Paltiel, MD, MSc Braun School of Public Health & Community Medicine Hebrew University of Jerusalem Hadassah Medical Organization Israel

2. Epidemiological Reasoning Using Cancer Statistics Or, how to use descriptive statistics to raise hypotheses

3. Issues to be discussed Validity of data Reporting Confounding Effect modification Using Descriptive Data Burden of Disease Planning Hypothesis raising Measuring progress

4. What are the objectives of epidemiology? 1. To determine the extent of disease (states of health) and/or behaviors in the community. 2. To identify the etiology or the cause/s of a disease and the risk factors - that is, factors that increase a person’s risk for a disease. 3. To study the natural history and prognosis of disease.

5. 4. To evaluate new preventive and therapeutic measures and new modes of health care delivery. 5. To provide the foundation for developing public policy and regulatory decisions relating to public health problems. Objectives of epidemiology

6. “When we measure, we know better” - Center for Disease Control (CDC), Atlanta, Georgia,USA

7. The epidemiological tool-box

8. Kaposi sarcoma in New York

9. The context of disease reporting

11. Lowest cancer death rate In the Former Yugoslav Republic of Macedonia, only 6 people per 100,000 of population die from cancer each year

12. Lifetime risk of developing breast cancer, 1940-1987

13. YEARONE IN…. 194020 195015 196014 197013 198011 1987 9 Source: American Cancer Society, 1991 Lifetime risk of developing breast cancer, 1940-1987 cont’d

14. Descriptive epidemiology - hypothesis raising rarely provides enough evidence for causation Person: characteristics for study include: Age Gender Religion Marital status Ethnicity Occupation Socio-economic class Heredity vs. Environment

15. Age-specific rates of Breast Cancer Mortality

16. Russian FederationIsrael Population Pyramids 1998

19. Trends of Cervical Cancer Mortality in Europe and North America

20. Age-standardized cervical cancer death rates (and 95% confidence intervals) per 100 000 women in urban Canada by neighbourhood income quintile from 1971 to 1996. Q1 = richest Q5 = poorest.

21. Place and time Time trends - raise hypotheses regarding environmental factors or results of medical care Geographic variation - on small + large scale, environmental  genetic factors Study of migrants: important for separating environmental from genetic factors

22. Numbers of cases of cancer at 16 anatomical sites in developed and in developing countries, with relative ranks

23. Lung Cancer Mortality for Women 1998, ASR/100000

24. Lung Cancer Mortality for men 1998, ASR/100000

25. Age-adjusted cancer death rates, males by site, US, 1930-1996

26. Age-adjusted cancer death rates, females by site, US, 1930-1996

28. Estimated annual percent changes in mortality from all types of cancer in the US over 2 periods 1973- 1990 and 1991-1995, according to age group

29. Japanese colon cancer incidence: JapanHawaiiCalifornia -  rate is affected by age at immigration - for breast cancer: 2 generations required for  rate Place and time cont’d Low Intermediate High

30. Biases in migrant studies 1) Different reporting 2) Different diagnostic criteria 3) Migrants are selected group

31. Clinical observation Descriptive data Hypothesis raising Where does evidence come from?

32. Clinical observation Descriptive data Hypothesis raising Analytical studies Hypothesis testing