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19 Cards in this Set
- Front
- Back
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Prospective cohort Defn
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Investigator defines and studies exposure variables prior to occurence of D
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Seven key questions to analyze a study
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Question
Design Cohort Followup Exposure Disease Confounders Analysis |
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3 parts to follow-up
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begin
end procedures |
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6 keys to exposure
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external
internal E- Zero time Classification Measurement Changes over time |
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4 keys to disease
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Definition
Acertainment Specificity/PPV Sensitivity |
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4 keys to Analysis
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Disease Occurrence
Effect Measure Statistical method Power |
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Follow-up: Procedure
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How subject tracked over time for both ascertain D and changes in E (or other vars). Problems include loss to follow-up and selection bias
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Exposure: External E- issues
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If E- group used is there a healthy worker effect
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Exposure: Internal E- issues
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non-random sampling
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Exposure: Classification
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dose, duration, timing.
clinically relevent divisions percentiles |
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Exposure: measurement issues
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misclass causes information bias: lead to null hypothesis
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Exposure: Change with follow-up
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misclassification - information bias which leads to null
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Disease: PPV issues
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misclass leads to null
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6 criteria for cohort members
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Relevant to question
Eligible (in theory) to be E+ Prevalence E+ adequate Susceptible to D Incidence D Adequate Can provide good data |
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Criteria for followup beginning
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Unambiguous.
data collection event. meeting criteria for inclusion. recruitment can be overtime. |
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Criteria for followup ending
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End of study
Study event Death any loss of followup |
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Common procedures for followup
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Interview
Contacts Tracing services Public records medicare death cert. |
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Effects of Loss of followup
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Seriously bias findings
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When to use prospective trial
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RCT can't be done
can't be answered with retrospective or case-control Can afford cost and time |
