1 Epidemiologic studies that are concerned with characterizing the amount and distribution of health and disease within a population. Descriptive Epidemiology Teach Epidemiology Making Group Comparisons and Identifying Associations

2 Epidemiologic studies that are concerned with determinants of disease and the reasons for relatively high or low frequencies of disease in specific population subgroups. Analytical Epidemiology Teach Epidemiology Making Group Comparisons and Identifying Associations

3 Hypothesis Formulating Descriptive Epidemiology Testing Analytical Epidemiology An unproven idea, based on observation or reasoning, that can be supported or refuted through investigation An educated guess Making Group Comparisons and Identifying Associations Teach Epidemiology

4 Hypothesis: Buprenorphine will stop heroin addicts from using heroin. Making Group Comparisons and Identifying Associations Teach Epidemiology

5 Population Trial 1 Making Group Comparisons and Identifying Associations

6 Population 500 Heroin Addicts Sample 100 Heroin Addicts 10 Weeks Trial 1 Making Group Comparisons and Identifying Associations

7 Population 150 Heroin Addicts Sample 100 Heroin Addicts 10 Weeks 21 Heroin Addicts Tested Negative for Heroin Trial 1 Making Group Comparisons and Identifying Associations

8 Bupe Tested Positive for Heroin Total Tested Negative for Heroin Trial 1 Teach Epidemiology Making Group Comparisons and Identifying Associations

9 When you can measure what you are speaking about, and express it in numbers, you know something about it. Lord Kelvin But when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind. Teach Epidemiology Making Group Comparisons and Identifying Associations

10 A measure of how often an outcome occurs in a defined population in a defined period of time. It consists of a numerator and a denominator. Risk The numerator is the number of people in the population or sample who experienced the outcome and the denominator is the total number of people in the population or sample. Population / Sample Outcome Denominator Numerator Teach Epidemiology Making Group Comparisons and Identifying Associations

11 … the risk of a positive heroin tests is 79 / 100 per 10-week period 79 tested positive for heroin 100 study subjects Numerator Denominator Teach Epidemiology Making Group Comparisons and Identifying Associations Risk

12 A measure of how often an outcome occurs in a defined group of people in a defined period of time. The likelihood of an outcome occurring. Risk / Rate Teach Epidemiology Making Group Comparisons and Identifying Associations

13 Trial 1 Bupe Tested Positive for Heroin Tested Negative for Heroin or 21 % Calculating Risk Teach Epidemiology Making Group Comparisons and Identifying Associations Risk of Negative Heroin Test Total

14 Process of predicting from what is observed in a sample to what is true for the entire population. Inference Teach Epidemiology Making Group Comparisons and Identifying Associations

15 Trial 1 What does this tell you about the hypothesis? Buprenorphine will stop heroin addicts from using heroin. Inference Probe Teach Epidemiology Making Group Comparisons and Identifying Associations Bupe Tested Positive for Heroin Tested Negative for Heroin or 21 % Risk of Negative Heroin Test Total

16 People who participate in a trial, but do not get the treatment. People whose results are compared to the group that was treated. Control Group Teach Epidemiology Making Group Comparisons and Identifying Associations

or 21 % Tested Positive for Heroin Tested Negative for Heroin Bupe Control Group Extend and label the table to include a control group. Teach Epidemiology Making Group Comparisons and Identifying Associations Risk of Negative Heroin Test Total

? or ? % No Bupe Control Group Making Group Comparisons Teach Epidemiology Making Group Comparisons and Identifying Associations or 21 % Tested Positive for Heroin Tested Negative for Heroin Bupe Risk of Negative Heroin Test Total

? or ? % No Bupe Making Group Comparisons Teach Epidemiology Making Group Comparisons and Identifying Associations or 21 % Tested Positive for Heroin Tested Negative for Heroin Bupe ExposureExposure Outcome / Disease ab cd Risk of Negative Heroin Test Total

or 21 % Total Bupe 100 ? or ? % No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test

21 A cross-classification of data where categories of one variable are presented in rows and categories of another variable are presented in columns The simplest contingency table is the 2x2 table. Contingency Table Teach Epidemiology Making Group Comparisons and Identifying Associations

22 Population 500 Heroin Addicts Sample 100 Heroin Addicts 10 Weeks 21 Heroin Addicts Tested Negative for Heroin Trial 1 Making Group Comparisons and Identifying Associations

23 Trial 2 Teach Epidemiology Making Group Comparisons and Identifying Associations Total ? 100 ? % a b c d Bupe Tested Negative for Heroin Tested Positive for Heroin No Bupe100 ? ? % Risk of Negative Heroin Test

24 E Assigned E O O O O Heroin Addicts Volunteer Heroin Addicts Teach Epidemiology Making Group Comparisons and Identifying Associations

% or a b c d Bupe Trial 2 No Bupe Probe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test

% or a b c d Bupe Trial 2 No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or

% or a b c d Bupe Trial 2 No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Inference: Process of predicting from what is observed in a sample to what is occurring in the entire population

28 When you can measure what you are speaking about, and express it in numbers, you know something about it. Lord Kelvin But when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind. Teach Epidemiology Making Group Comparisons and Identifying Associations

29 The value obtained by dividing one quantity by another Ratio Teach Epidemiology Making Group Comparisons and Identifying Associations

% or a b c d Bupe Trial 2 No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Ratio: The value obtained by dividing one quantity by another Risk Ratio: The ratio of two risks 1 Risk Ratio

% or a b c d Bupe Trial 2 No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Ratio: The value obtained by dividing one quantity by another Risk Ratio: The ratio of two risks 1 Risk Ratio Create a formula a a + b c c + d

% or a b c d Bupe Trial 2 No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or 1 Risk Ratio Relative Risk: The ratio of the risk of an outcome among the exposed to the risk of the outcome among the unexposed. Relative Risk

% or a b c d Bupe Trial 2 No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or 1 Risk Ratio Relative Risk Inference: Process of predicting from what is observed in a sample to what is occurring in the entire population The inference here is that there is no effect of Buprenorphine

34 Trial 3 Teach Epidemiology Making Group Comparisons and Identifying Associations ? 100 ? % 100 or a b c d Bupe No Bupe Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test ? 100 ? % 100 or

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Trial 3

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Trial 3

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Inference: Process of predicting from what is observed in a sample to what is occurring in the entire population Trial 3

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Relative Risk Relative Risk: The ratio of the risk of an outcome among the exposed to the risk of the outcome among the unexposed Trial 3

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Relative Risk 0.34 The heroin addicts who received Bupe were ___ times as likely to use heroin as those who did not receive Bupe Trial 3

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Relative Risk 0.34 Inference: Process of predicting from what is observed in a sample to what is occurring in the entire population. Trial 3

41 Trial 4 Teach Epidemiology Making Group Comparisons and Identifying Associations ? 100 ? % 100 or a b c d Bupe No Bupe Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test ? 100 ? % 100 or

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Trial 4

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Trial 4

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Relative Risk Relative Risk: The ratio of the risk of an outcome among the exposed to the risk of the outcome among the unexposed. 3.5 Trial 4

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Relative Risk 3.5 The heroin addicts who received Bupe were ___ times as likely to use heroin as those who did not receive Bupe. 3.5 Trial 4

% or a b c d Bupe No Bupe Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test % or Relative Risk 3.5 Inference: Process of predicting from what is observed in a sample to what is occurring in the entire population. Trial 4

% or Bupe Trial 1 Teach Epidemiology Making Group Comparisons and Identifying Associations Total Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test What do the results tell us about the hypothesis that Buprenorphine will stop heroin addicts from using heroin? Nothing

48 Trial 1 Trial 2 Trial 3 Trial 4 Making Group Comparisons and Identifying Associations Teach Epidemiology

49 Nothing Bupe Total Trial 1 Trial 2 Trial 3 Trial 4 Making Group Comparisons and Identifying Associations Teach Epidemiology Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin or 21%

50 Risk of Negative Heroin Test Nothing Bupe Total Trial 1 Trial 2 Trial 3 Trial 4 Bupe No Bupe Bupe No Bupe Bupe Total Relative Risk No Bupe Total Relative Risk Total Tested Negative for Heroin Tested Positive for Heroin Relative Risk Making Group Comparisons and Identifying Associations Teach Epidemiology Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin or 21%

51 Risk of Negative Heroin Test Nothing Bupe Total Trial 1 Trial 2 Trial 3 Trial 4 Bupe No Bupe Bupe No Bupe Bupe Total Relative Risk No Bupe Total Relative Risk Total Tested Negative for Heroin Tested Positive for Heroin Relative Risk Making Group Comparisons and Identifying Associations Teach Epidemiology Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin or 21% or 21% or 21% or 21%

52 Risk of Negative Heroin Test Nothing Bupe Total Trial 1 Trial 2 Trial 3 Trial 4 Bupe No Bupe Bupe No Bupe Bupe Total Relative Risk No Bupe Total Relative Risk Total Tested Negative for Heroin Tested Positive for Heroin Relative Risk Making Group Comparisons and Identifying Associations Teach Epidemiology Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin or 21% or 21% or 21% or 21% or 21% Bupe is not associated with having a negative tests for heroin.

53 Risk of Negative Heroin Test Nothing Bupe Total Trial 1 Trial 2 Trial 3 Trial 4 Bupe No Bupe Bupe No Bupe Bupe Total Relative Risk No Bupe Total Relative Risk Total Tested Negative for Heroin Tested Positive for Heroin Relative Risk Making Group Comparisons and Identifying Associations Teach Epidemiology Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin or 21% or 21% or 21% or 21% or 21% Bupe is not associated with having a negative tests for heroin or 62% Bupe is associated with having a positive test for heroin!.34

54 Risk of Negative Heroin Test Nothing Bupe Total Trial 1 Trial 2 Trial 3 Trial 4 Bupe No Bupe Bupe No Bupe Bupe Total Relative Risk No Bupe Total Relative Risk Total Tested Negative for Heroin Tested Positive for Heroin Relative Risk Making Group Comparisons and Identifying Associations Teach Epidemiology Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin or 21% or 21% or 21% or 21% or 21% Bupe is not associated with having a negative tests for heroin or 62% Bupe is associated with having a positive test for heroin! or 6% Bupe is associated with having a negative test for heroin. 3.5

55 Risk of Negative Heroin Test Nothing Bupe Total Trial 1 Trial 2 Trial 3 Trial 4 Bupe No Bupe Bupe No Bupe Bupe Total Relative Risk No Bupe Total Relative Risk Total Tested Negative for Heroin Tested Positive for Heroin Relative Risk Making Group Comparisons and Identifying Associations Teach Epidemiology Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin Risk of Negative Heroin Test Tested Negative for Heroin Tested Positive for Heroin or 21% or 21% or 21% or 21% or 21% Bupe is not associated with having a negative tests for heroin or 62% Bupe is associated with having a positive test for heroin! or 6% Bupe is associated with having a negative test for heroin. 3.5 Nothing Compared to what?

56 6. Buprenorphine Buprenorphine & Naloxone Placebo Handout Teach Epidemiology Making Group Comparisons and Identifying Associations