Lecture 1 Flashcards
Intro (25 cards)
Definition of epidemiology
quantitative study of the distribution, determinants and control of disease in populations
How do epidemiologists describe the occurrence of cancer?
Sex, age, race, socioeconomic status, occupation, time period, geographic region, country…
What 2 factors do they look for a relationship between?
1) exposure (risk factor)
2) the disease
When did John Snow look at the cholera epidemic
1854
When did Henry Butlin conduct research
1892
What was Henry Butlin’s research about
‘Three lectures on cancer of the scrotum in chimney sweeps and others’
Noted this cancer was exclusively in England - germany wore a close fitting suit and the english wore loose smock and trousers
Concluded that cause was lack of protective clothing
What was the first international classification edition?
International List of Causes of Death (1850-60s)
Why was the international list of causes of death important?
Improved comparability of international mortality statistics because it was adopted by many countries to code the cause of death
When was the first international cancer mortality statistics?
1915
What happened to epidemiology in the 20th century
Shifted to non-communicable diseases
What did Doll & Hill report on? (first one)
Lung cancer and smoking (1950)
Hypothesised rising incidence of lung cancer related to rising prevalence of tobacco smoking
What did Doll & Hill study? (second one)
British Doctors (1954) (Follow up study)
Prospective cohort study on effects of smoking on cause-specific mortality
What type of study was the Doll and Hill 1950?
Case-control study
What was the findings of the Doll and Hill 1950?
Odds ratio of 14 and p value of <0.0001
Means smoking associated with 14 times increased risk of lung cancer
What did the british doctor study consist of?
Questionnaire on smoking habits sent to all registered British doctors
40,701 included in follow-up
Further questionnaire sent in 1957, 1966, 1971, 1978, 1991, 1998, 2001
What did the british doctor study aim to achieve?
Range of outcomes of smoking (not just lung cancer) and provided ongoing evidence of smoking and disease’s relationship
What are the 4 classic features of epidemiology?
- Measured distribution of disease in a population (time, place and person)
- Identified determinants of disease within and between populations (factors associated with increases/decreases in disease)
- Intervention to control disease
- Formulation and implementation of effective public health policy
What are some recent advances in cancer epidemiology?
Molecular techniques provide new insights by using biomarkers to improve exposure assessment, document early changes preceding disease and identify subgroups in population with greater susceptibility to cancer
What is a cohort study?
Group of people without the disease of interest are used and data is collected to identify those that are exposed to a particular factor (e.g. smokers and non-smokers)
This group then followed over time and disease occurrence in the unexposed
What is a positive of a cohort study?
Strong evidence between risk factor exposure and cancer incidence
What is a negative of a cohort study?
Costly and logistically difficult
Cancer occurs rarely so large number of people must be followed up for a long period of time to observe enough cases with the disease
What is a case-control study?
Comparing a group of people with the disease of interest (cases) with a group without the disease (controls) to see whether groups differ in their past history of exposures
What is a positive of case-control studies?
Well suited to cancer and diseases with long latency periods as it looks back though time (reverse of cohort studies)
What is a cross-sectional study?
Collect observations on individuals at one point in time to determine frequency of a factor
‘Snapshot’ of the health of a population
Observation may be on an exposure or disease status or both
When collected, associations can be made
