Introduction to Epidemiology Flashcards
What is mortality rates? and what is needed for a meaningful statistic
The threat of death (death rates). A meaningful statistic needs a denominator population and a time frame.
What are some examples of denominators used in mortality rates?
Health boards, cities and hospitals (it picks specific groups of people/areas)
What is person-time?
The number of years a person is exposed to a risk.
What is incidence and how can you calculate incidence rate?
Incidence = the number of new cases
Incidence rate = number of people with disease/number of people at risk x 100,00 (to get the rate in 100,000) people
Define prevalence?
-Proportion of population that has a disease
How can you calculate point prevalence rate and period prevalence rate?
Point prevalence rate = number of people with disease at a point of time/ Total number of people in the group x 100
Period prevalence rate = number of people with a disease over a period of time/average number of people in the group x 100
What are the differences between incidence and prevalence?
Incidence is a rate or a proportion, it is useful for identifying the cause of disease.
Prevalence is a proportion and identifies disease burden.
Define sporadic
Occasional cases occurring irregularly
Define endemic
Persistent background level of occurrence
Define epidemic
Occurrence in excess of the expected level for a given time period
Define pandemic
Epidemic occurring or spreading over more than one continent
What can different types of outcomes be?
Death, Hospitalisation, Diagnosis, Relapse, Difference in quality of life, Surrogates (changes in blood pressure or lung function)
What can different exposures be? (factors that lead to an outcome)
Non-modifiable - age and genotype.
Modifiable - smoking, weight, exercise, diet, alcohol consumption.
Interventions - Drugs, surgery and lifestyle advice
What is risk?
The percentage of the number of outcomes in a group/number of people in the group
what is relative risk?
The ration of the people exposed to the people unexposed
What is relative risk reduction?
(1-relative risk) x 100
What is the absoloute risk reduction?
Risk in unexposed - risk in exposed
What is the number needed to treat?
1/absolute risk reduction
What is a confidence interval?
They represent the range of plausible values. Wider the intervals, the greater the uncertainty. So this makes them very useful in appraising published research.
Describe the hierarchy of evidence
It ranges from the most reliable sources (systematic reviews and meta-analysis), then experimental designs, quasi-experimental designs, then observational-analytic designs and observational descriptive designs. To the least reliable (background information and expert opinion)
What is a cross-sectional study?
Looks at the different; exposures, signs/symptoms and outcomes. The data can be used to look at prevalence and associations
What is a case-control study?
This samples cases with outcomes and without outcomes. It explores and compares exposures and helps identify associations (looking at cause)
What is a cohort study?
It compares the risk of the disease in the unexposed and exposed and looks at the cause, prognosis and incidence.
What is a randomised controlled trial?
It uses the randomised use of intervention and controls. It is used to compare the risk of outcome in intervention and control groups
What are the different study designs good for?
Randomised controlled trial - looks at treatment effect
Cohort - looks at cause, prognosis and incidence
Case controlled - cause
Cross sectional - prevelence.
