队列分析研究

The Framingham Study

Since 1948, samples of residents of Framingham, Massachusetts, have been subjects of investigations of risk factors in relation to the occurrence of heart disease and other outcomes


Tobacco smoking and habitual use of alcohol are associated with an increased incidence of CHD.
Increased physical activity is associated with a decrease in development of CHD. An increase in body weight predisposes a person to CHD.
Basic principle
• The research object will be divided into exposure group and unexposure group due to the research object whether exposure to certain study factors or the different levels • Then follow-up visit
Risk factor
• Referring to can cause a particular adverse outcome, or the factors that can increased the probability of occurrence of the adverse outcome. • Include Individual behavior lifestyle Environmental and genetic
Continue to prospective collect data Data collected prospectively prospective cohort study
Time sequence
Exposure
Study starts
Disease occurrence
？
time
Exposure Disease occurrence Study starts
？
time
Study starts
Exposure
Disease occurrence
？
time
Prospective Cohort Study
The study cohort certainty is now (concurrent)
Exposed groups according to the research object now Need follow-up (follow-up) End at some point in the future to appear
Historical (Retrospective) Cohort Study
The study cohort certainty is past Exposed groups according to the research object past Don't need follow-up study
Design Features
•Strengths (cont.):
•• Enhance credibility with time going on •• Direct access to information ,Results are more credible •• Can obtain the incidence
The Framingham Study

Study population consisted of 5,127 men and women between ages 30 and 62 years and were at the time of entry free of cardiovascular disease (1948-1952)
Research types
• prospective cohort study • historical cohort study • ambispective cohort study
Types of Cohort Studies
• Prospective cohort study • Exposure baseline in the present • Follow-up period: present to future • Historical cohort study • Exposure baseline in the past • Follow-up period: past to present
Fixed Cohort
Appear end ppear no end
Study began
Research to end
• OPEN - people moving in and out
Dynamic Cohort
Appear end Lost to
Study began
Research to end
N
Ē
Time sequence
Y
N
Main features
• Observational method • Establish control • The cause and effect , accord with time sequence • Corroborate the relationship between exposure and outcome
Design Features
•Limitations:
•• Can be very costly and time consuming. •• Often requires a large sample size.
Prospectie cohort study of application conditions
Cohort Studies
• Forward looking. The most powerful of observational studies • Follow groups of individuals free from disease through a period of time • Quantified with relative risk/incidence rates/attributable risk
• Ambispective cohort study: – Exposure baseline in the past • Follow-up period: past to present to future
Cohort study data collection
DESIGN PAST PRESENT FUTURE
Multi-Sample Cohort Study Design
TIME
Disease Study Cohor t Control Cohort Exposed Not Diseased Diseade d Not Diseased
Not Exposed
Single Sample Cohort Study Design
Prospective Historical Ambispective
E E
E D E
D
D
In the past
now
historical cohort study
In the future
ambispective cohort study
Retrospectively collected existing historical material
•Clearly inspection hypothesis
•A high incidence of disease research, generally not be less than 5 ‰
•Clearly stipulates exposure factors and ending variables
Research purpose
• Inspection cause hypothesis ( hypothesis) • Evaluate preventive measures effect (effect of prevention) • To study of disease of natural history ( natural history of disease) • New drugs after the listing surveillance
Sutdy started ,end already appeared
Optimal point
Short-term collection and analysis of complete information
The results by reasons as time going on
• Exposure
• Refers to contact with some material, have some characteristics or in some states.
• fixed cohort
• Cohort
• •
dynamic cohort
• CLOSED - fixed population