HaDPOP Flashcards
Define: Crude Birth Rate
The total number of live births per 1000 people in a given year.
Define: General Fertility Rate
The total number of live births per 1000 women aged 15-44, in a given year.
Define: Total Fertility Rate
The average number of children a hypothetical woman would have in her life time.
Define: Crude Death Rate
The total number of deaths per 1000 people in a given year.
Define: Age-specific Death Rate
The total number of deaths per 1000 people in a specific age range, in a given year.
Define: Standard Mortality Ratio
Compares the number of observed and expected deaths, if age-sex distribution was identical.
Define: Standard Morbidity Ratio
Compares numbers of observed and expected individuals with a condition, if age-sex distribution was identical.
Define: Incidence
The number of new cases of a disease.
Define: Prevalence
The total number of people affected by a disease. (PREVALENCE IS NOT A RATE).
Equation for Incidence Rate
(Number of new cases) / (Population * Time)
Normal Units = People-years
Prevalence equation relating to Incidence
Prevalence = Incidence * Length of disease
P = I * L
Incidence Rate Ratio Equation
(Incidence Rate Exposed) / (Incidence Rate Not Exposed)
Define: Absolute Risk
Absolute risk measures the size of risk in an individual or a group of people.
Define: Relative Risk
Relative risk compares risk in two groups of people
Define: Confounding Factor
A factor which is associated to both the disease of interest and the exposure of interest without being part of the causal pathway.
Define: Confidence Interval
A range of values so defined that there is a specified probability that the true value of a parameter lies within it.
Define: Statistical Significance
If the results of a test have statistical significance, it means they are not likely to have occurred by chance alone. In such cases, we can be more confident we are observing the true result.
Define: Cohort Study
This study follows a group people over a period of time and is to see how their exposure affects their outcome.
Define: Selection Bias
The distortion of results or data as a result of the way they were gathered.
Define: Survivor Bias
The logical error of concentrating on those who survived a situation, and overlooking those who didn’t. Can result in false conclusions being drawn.
Define: Phocamelia
Shortening of the limbs due to malformation.
Define: Conception
Live births + Miscarriages + Abortions
If p> 0.05
Cannot reject null hypothesis
If p
Can reject null hypothesis
How many significant figures do we use in exams?
3.
Benefits of Cohort Studies
- Allows detailed + prospective assessments
- Can study a range of outcomes at once
- Best for conditions which vary with age
Disadvantages of Cohort Studies
- Resource intensive
- Take a long time
- Survivor bias - people may leave study.
Define: Census
The simultaneous collection of demographic data by the government at a particular time pertaining to all people living in a certain territory.
Define: Endogenous Infection
Infection by an agent already in the body.
Define: Exogenous Infection
Infection by an agent coming in from outside of the body.
With an internal comparison of cohort studies, what method can you use to compare cohorts?
Incidence Rate Ratio
With an external comparison of cohort studies, what method can you use to compare cohorts?
Standard Mortality Ratio calculation (removes confounders)
What is the healthy worker effect?
This is a type of biasing, caused by comparing workers to non-workers. It can be assumed that those working are healthier than those not (as they are working) and therefore is a form of selection bias.
Describe the table used to draw up results of case-control study (used also to find odds ratio).
Cases Controls
Exposed
Unexposed
Odds ratio equation?
OR = (AD)/(BC)
Name two types of bias possible from case-control studies.
- Selection bias (where did we select cases and controls from?
- Recall bias (have we correctly determined exposure status?)
Cohort or Case control?
Better at looking at rare exposures
Cohort
Cohort or Case control?
Better at looking at rare outcomes
Case Control
Cohort or Case control?
Opportunity to look at multiple outcomes at once
Cohort
Cohort or Case control?
Opportunity to loom at multiple exposures at once
Case Control
Cohort or Case control?
Expensive + Time consuming but allows specific absolute risk calculation.
Cohort
Cohort or Case control?
Cheap + quick but can’t obtain absolute risks (unless nested)
Case Control
What is a Randomised Controlled Trial?
This is an experiment type where individuals are randomly assigned to one of two groups. Both groups are treated identically except for a change in a key aspect (eg. drug).
Do RCTs remove confounders?
Yes, as they are randomised.
Why must we use placebos?
This is to remove the placebo effect from the trial
What is intention-to-treat analysis?
This is where results from everybody in the study is included, even those who dropped out. Gives realistic view of what drug will actually be like in the public domain.
What is As-treated analysis?
This is where results from only those who completed a trial are included. Can make the treatment look better than it actually is - pharmaceutical companies use this often.
What is double-blinding?
This is when atleast 2 of the patients, investigators and clinicians are blinded in a trial.
Give the 9 Bradford Hill Criteria
Some Silly Children Can't Be Asked To Do Revision S- Strength of association S - Specificity of association C - Consistency of association C - Coherence of theory B - Biological Plausibility A - Analogy T - Temporal Sequence D - Dose response R - Reverisibility
What do the Bradford Hill Criteria aim to determine?
A causal-effect relationship
Name 5 ethics of a RCT
- Clinical Equipose
- Scientifically robust
- Ethical recruitment
- Valid consent
- Voluntariness
Name the 4 individual ethics for any medical role.
- Beneficence
- Non-maleficence
- Autonomy
- Justice
Difference between a systematic review and a meta-analysis?
Systematic review = Compilation of primary studies
Meta-analysis = Statistical approach comparison derived
from systematic review.
For a systematic review, name 3 features a study should be.
- Transparent
- Explicit
- Reproducible
Difference between fixed effects model and random effects model?
Fixed effects model = All primary studies are aiming for the same true value and any deviation is due to within-study variation.
Random effects model = All studies are heterogeneous and aim for different true values. Any variation comes from within-study and between-study variation.
What are funnel plots used to show?
Publication bias.
What are forest plots used to show?
Meta-analysis data.
How should we interpret p values for heterogeneity?
Bigger numbers are less significant heterogeneity. Due to low power of test, we use p