DrugEpi 6 - Reverse Time Order Module 4 Overview Context Content Area: Interpretation of...
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Transcript of DrugEpi 6 - Reverse Time Order Module 4 Overview Context Content Area: Interpretation of...
DrugEpi 6 - Reverse Time Order
Module 4 OverviewContext
Content Area: Interpretation of Epidemiological EvidenceEssential Question (Generic): Is the association causal? Essential Question (Drug Abuse Specific): Is an association with drug abuse causal?Enduring Epidemiological Understanding: Causation is only one explanation for finding an association between an exposure and a disease. Because observational studies are complicated by factors not controlled by the observer, other explanations must also be considered.
Synopsis: In Module 4, students explore the rationale and methods of interpreting epidemiological studies. Students develop skills to assess possible explanations for an association found in a study, with consideration of explanations of causality, chance, confounding, reversed time order, and bias. Module 4 concludes with consideration of methods for weighing the overall evidence for an association.
Lessons:
Lesson 4-1: Introduction to Interpreting AssociationsLesson 4-2: CausalityLesson 4-3: Chance Lesson 4-4: Bias Lesson 4-5: ConfoundingLesson 4-6: Reverse Time Order Lesson 4-7: Weighing the Evidence
DrugEpi 6 - Reverse Time Order
Module 4 - Interpretation of Epidemiological Evidence
Lesson 4-6 - Reverse Time Order
Content
• Definition and explanation of reverse time order• Examples of exposure/outcome scenario that illustrate how reverse time
order can be considered• Example of an improved epidemiologic study design to determine whether
or not there could be reverse time order
Big Ideas
• Association does not necessarily mean causation• When an association is found, several possible explanations must be
considered, including the possibility that the association is due to reverse time order
This project is supported by a Science Education Drug Abuse Partnership Award, Grant Number 1R24DA016357-01, from the National Institute on Drug Abuse,
National Institutes of Health.
DrugEpi 6 - Reverse Time Order
Where Are We?
Essential Questions Enduring Understandings
1. How is this disease distributed?
Health-related conditions and behaviors are not distributed uniformly in a population. They have unique distributions that can be described by how they are distributed in terms of person, place, and time.
2. What hypotheses might explain the distribution of disease?
Clues for formulating hypotheses can be found by observing the way a health-related condition or behavior is distributed in a population.
3. Is there an association between the hypothesized cause and the disease?
Causal hypotheses can be tested by observing exposures and diseases of people as they go about their daily lives. Information from these observational studies can be used to make and compare rates and identify associations.
4. Is the association causal?
Causation is only one explanation for an association between an exposure and a disease. Because observational studies are complicated by factors not controlled by the observer, other explanations also must be considered.
5. What should be done when preventable causes of disease are found?
Policy decisions are based on more than the scientific evidence. Because of competing values - social, economic, ethical, environmental, cultural, and political factors may also be considered.
DrugEpi 6 - Reverse Time Order
Reverse Time Order
Is the association due to
reverse time order?
1. Cause
2. Chance
3. Chance
Confounding
Reverse Time Order
4.
5.
DrugEpi 6 - Reverse Time Order
Which came first?
Egg Chicken
“The Riddle” by Charles Bragg
DrugEpi 6 - Reverse Time Order
Scenario 1
DrugEpi 6 - Reverse Time Order
Scenario 2
DrugEpi 6 - Reverse Time Order
Which came first?
Egg Chicken
“The Riddle” by Charles Bragg
DrugEpi 6 - Reverse Time Order
Definition
When the hypothesized time order of an exposure and an outcome is
actually reversed and the outcome really comes before the exposure.
Reverse Time Order
DrugEpi 6 - Reverse Time Order
Time
Random Assignment
E
E
DZ
DZ
DZ
DZ
Healthy People
Flow Diagram
-
Trial
DrugEpi 6 - Reverse Time Order
E
E
DZ
DZ
DZ
DZ
Healthy People
-
Time
Cohort
Study
Flow Diagram
DrugEpi 6 - Reverse Time Order
DZ
DZ
E
E
E
E
-
Time
Case-Control
Study
Flow Diagram
DrugEpi 6 - Reverse Time Order
DZ
DZ
E
E
-
Time
Cross-
Sectional
Study
Flow Diagram
DrugEpi 6 - Reverse Time Order
Which came first? Exposure or Outcome?
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Random Assignment
-
E
E
DZ
DZ
DZ
DZ
Study Design: Trial
Healthy People
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
E
E
DZ
DZ
DZ
DZ
Study Design: Cohort Study
Healthy People
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
DZ
DZ
E
E
E
E
Study Design: Case-Control Study
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
DZ
DZ
E
E
Study Design: Cross-Sectional Study
DrugEpi 6 - Reverse Time Order
Which came first? Exposure or Outcome?
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Random Assignment
-
E
E
DZ
DZ
DZ
DZ
Study Design: Trial
Healthy People
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
E
E
DZ
DZ
DZ
DZ
Study Design: Cohort Study
Healthy People
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
DZ
DZ
E
E
E
E
Study Design: Case-Control Study
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
DZ
DZ
E
E
Study Design: Cross-Sectional Study
1st 2nd
3rd 4th
DrugEpi 6 - Reverse Time Order
Which came first?
Exposure Outcome
“The Riddle” by Charles Bragg
DrugEpi 6 - Reverse Time Order
Scenario 3
Watching TV
No Watching TV
Overweight
No Overweight
Watching TV Overweight
DrugEpi 6 - Reverse Time Order
b
d
a
c
Risks
Count
CompareDivide
Over-weight
No Over-weight
TV
No TV
23 9 or 71.8%32
23
7 15
32
22 or 31.8%22
7
Relative Risk
= 2.3
Total
Count, Divide, and Compare (CDC)
Is there an association?
Did watching TV and being overweight turn up together?
DrugEpi 6 - Reverse Time Order
Watching TV
Time Order
Watching TV
No Watching TV
Overweight
No Overweight
Overweight
Watching TV
causes
people to be
overweight.
DrugEpi 6 - Reverse Time Order
Watching TV
No Watching TV
Overweight
No Overweight
Watching TV OverweightX
Time Order
Watching TV
causes
people to be
overweight.
DrugEpi 6 - Reverse Time Order
Watching TV
No Watching TV
Overweight
No Overweight
Watching TV OverweightX
Watching TV
causes
people to be
overweight.
Time Order
DrugEpi 6 - Reverse Time Order
It is possible that people who __________ are more likely to ____________.
But it is also possible that people who are __________
are more likely to __________.
Reversed Time Order
watch TV
be overweight
watch TV
overweight
DrugEpi 6 - Reverse Time Order
Which came first?
Watching TV Overweight
“The Riddle” by Charles Bragg
DrugEpi 6 - Reverse Time Order
Watching TV causes weight gain.
Watching TV
No Watching TV
Overweight
No Overweight
Watching TV Overweight
Cigarette Smoking
No Cigarette Smoking
Depression
No Depression
Scenario 4
Cigarette Smoking
Depression
DrugEpi 6 - Reverse Time Order
b
d
a
c
Count
CompareDivide
38 83
59 196
121
255
121
Risks
or 31.4%38
or 23.1%255
59
Relative Risk
= 1.4
Depress-ion
No
Depress-ion
Cigarette Smoking
No
Cigarette Smoking
Total
Is there an association?
Did cigarette smoking and depression turn up together?
Count, Divide, and Compare (CDC)
DrugEpi 6 - Reverse Time Order
Watching TV causes weight gain.
Watching TV
No Watching TV
Overweight
No Overweight
Watching TV Overweight
Cigarette Smoking
No Cigarette Smoking
Depression
No Depression
Time Order
Cigarette Smoking
Depression
Cigarette
smoking
causes
depression.
DrugEpi 6 - Reverse Time Order
Watching TV
No Watching TV
Overweight
No Overweight
Watching TV Overweight
Cigarette Smoking
No Cigarette Smoking
Depression
No Depression
Cigarette Smoking
DepressionX
Cigarette
smoking
causes
depression.
Time Order
DrugEpi 6 - Reverse Time Order
Watching TV
No Watching TV
Overweight
No Overweight
Watching TV Overweight
Cigarette Smoking
No Cigarette Smoking
Depression
No Depression
Cigarette Smoking
DepressionX
Cigarette
smoking
causes
depression.
Time Order
DrugEpi 6 - Reverse Time Order
It is possible that people who _____________
are more likely to ____________.
But it is also possible that people who are __________
are more likely to ______________.
Review - Reversed Time Order
smoke cigarettes
be depressed
smoke cigarettes
depressed
DrugEpi 6 - Reverse Time Order
Which came first?
Cigarette Smoking
Depression
“The Riddle” by Charles Bragg
DrugEpi 6 - Reverse Time Order
Family Meals
No Family Meals
No Substance
Use
Substance Use
Frequent Family Meals and Lack of Substance Use
Family MealsNo
Substance Use
DrugEpi 6 - Reverse Time Order
“Having family
meals often
may well
decrease
substance use”
Family MealsNo Substance
Usex
Family Meals
No Family Meals
No Substance
Use
Substance Use
Frequent Family Meals and Lack of Substance Use
DrugEpi 6 - Reverse Time Order
It could be that …
using substances
may lead to
avoidance of family
meals . . .
Family MealsNo Substance
Usex
Family Meals
No Family Meals
No Substance
Use
Substance Use
Frequent Family Meals and Lack of Substance Use
DrugEpi 6 - Reverse Time Order
Which came first?
Family Meals Substance Use
“The Riddle” by Charles Bragg
DrugEpi 6 - Reverse Time Order
It is possible that people who ________________
are more likely to __________________.
But it is also possible that people who
_______________ are more likely to _______________.
Review - Reversed Time Order
attend family meals
not abuse substances
avoid family meals
use substances
DrugEpi 6 - Reverse Time Order
Reverse Time Order
How can I figure out if the association is
due to reverse time order?
DrugEpi 6 - Reverse Time Order
Which came first? Exposure or Outcome?
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Random Assignment
-
E
E
DZ
DZ
DZ
DZ
Study Design: Trial
Healthy People
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
E
E
DZ
DZ
DZ
DZ
Study Design: Cohort Study
Healthy People
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
DZ
DZ
E
E
E
E
Study Design: Case-Control Study
Time
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
-
DZ
DZ
E
E
Study Design: Cross-Sectional Study
DrugEpi 6 - Reverse Time Order
ME Eisenberg, D Neumark-Sztainer, JA Fulkerson, M Story. Family meals and substance use: Is
there a long-term protective association? Journal of Adolescent Health 43
(2008) 151-156
A Study to Test Time Order
DrugEpi 6 - Reverse Time Order
ME Eisenberg, D Neumark-Sztainer, JA Fulkerson, M Story. Family meals and substance use:
Is there a long-term protective association? Journal of Adolescent Health 43 (2008) 151-156
A Study to Test Time Order
“Most studies regarding health benefits of family meals have used a cross-sectional design . . .”
“Cross-sectional studies . . . lay important groundwork but raise the question of reverse causality . . .”
“The present study therefore builds upon or earlier cross-sectional research . . .”
“We examine family meal patterns over 5 years and their association with initiation of substance use as young people transition from middle school to high school age.”
“We hypothesize that regular family meals during early adolescence will be protective against substance use in middle adolescence, 5 years later.”
DrugEpi 6 - Reverse Time Order
E
E
DZ
DZ
DZ
DZ
Healthy People
-
Time
Cohort
Study
Flow Diagram
Yes/No 5 or more
family meals per week
Yes/No Development of substance use
Teenagers substance use at start
of study
DrugEpi 6 - Reverse Time Order
Abstract of Journal Report on Study
Purpose: To examine 5-year longitudinal associations between family meal patterns and subsequent substance use in adolescents.
Methods: A total of 806 Minnesota adolescents were surveyed in public schools in 1998–1999 (mean age, 12.8 years) and again by mail in 2003–2004 (mean age, 17.2 years) . . . [We] estimated] the odds of tobacco, alcohol, and marijuana use at follow-up for adolescents reporting regular family meals at baseline compared with those without regular family meals, adjusting for family connectedness and prior substance use.
Results: Family meal frequency at baseline was associated with significantly lower odds of cigarette smoking, alcohol use, and marijuana use at follow-up among female adolescents, even after adjusting for baseline substance use and additional covariates. Family meals were not associated with use of any substance at follow-up for male adolescents after adjusting for baseline use.
Conclusions: Results from this study suggest that regular family meals in adolescence may have a long-term protective association with the development of substance use over 5 years among females. Parents should be encouraged to establish a pattern of regular family meals, as this activity may have long lasting benefits
DrugEpi 6 - Reverse Time Order
Detail about Study Findings
Gender / Exposure
Relative Odds (95% Confidence Interval - CI)
* **
Say it in English
Girls
Cigarettes
Alcohol
Marijuana
0.47 (0.29-0.81)
0.49 (0.29 - 0.83)
0.49 (0.26 - 0.93)
The odds of using _____________
are ______ times as
likely for those who have
5 or more family
meals per week
as for those who do not
Boys
Cigarettes
Alcohol
Marijuana
0.67 (0.39 - 1.21)
0.91 (0.53 - 1.55)
0.98 (0.54 - 1.76)
* Analyses account for “family connectedness,” race, socioeconomic status and baseline substance use
** 95% CI means that 95 of 100 studies, this CI contains the true odds ratio
DrugEpi 6 - Reverse Time Order
Interpretation
Why is the protective effect seen only in girls?
Eisenberg in article: “This study's findings also are in line with our previous findings suggesting that family meals may be associated with more benefits for females than for males. Although measures were not available to explore reasons behind this difference in the current study, existing theory and research point to differences in the way that males and females interact with family members in a variety of domains. Females may, for example, be more attuned to subtle emotional support offered during family meals, resulting in a more profound protective effect for females than for males.”
DrugEpi 6 - Reverse Time Order
Exposure Outcome
If an association was found due to reversed time-order, ….found due to reverse time order, ….
Public Health Significance of Reverse Time Order
X… and you avoided or eliminated the hypothesized
cause, what would happen to the outcome?
?
DrugEpi 6 - Reverse Time Order
Big Ideas in this Lesson (4-6)
• Association does not necessarily mean causation
• When an association is found, several possible
explanations must be considered, including the
possibility that the association is due to reverse
time order
Re-Cap
DrugEpi 6 - Reverse Time Order
Next Lesson
Amicus Curiae
Friend of the Court