Modules 10-23 Onward Flashcards
What are different kinds of experimental studies?
clinical trials
prevention trials
therapeutic trials
community trials
What is a clinical trial?
are research studies that test a medical, surgical, or behavioral intervention in people. These trials are the primary way that researchers determine if a new form of treatment or prevention, such as a new drug, diet, or medical device (for example, a pacemaker), is safe and effective in people.
What is a prevention trial?
evaluates whether an intervention reduces the risk of a disease in a population that is / was free of said disease
What is a therapeutic trial?
Assesses new screening or diagnostic methods
What are community trials?
interventions aimed at the population level
considered quasi experiments
What is a randomized control trial?
The randomised control trial (RCT) is a trial in which subjects are randomly assigned to one of two groups: one (the experimental group) receiving the intervention that is being tested, and the other (the comparison group or control) receiving an alternative (conventional) treatment (fig 1).
What is the Hawthorne effect?
The Hawthorne effect refers to people’s tendency to behave differently when they become aware that they are being observed
What is the placebo effect?
The placebo effect is when a person’s physical or mental health appears to improve after taking a placebo or ‘dummy’ treatment.
What is the principle of equipoise
The principle of equipoise states that, when there is uncertainty or conflicting expert opinion about the relative merits of diagnostic, prevention, or treatment options, allocating interventions to individuals in a manner that allows the generation of new knowledge (eg, randomization) is ethically permissible.
What are the two measures of efficacy?
Superiority test (is one method better than the other?) and equivalence test (is one treatment no better or worse than the other?)
What is efficacy versus effectiveness?
Efficacy is the degree to which a vaccine prevents disease, and possibly also transmission, under ideal and controlled circumstances – comparing a vaccinated group with a placebo group.
Effectiveness meanwhile refers to how well it performs in the real world
Describe efficacy calculations
What is the measure of association for experimental epidemiology?
efficacy
what is blinding or masking?
Describe different methods of randomization
Describe the 4 phases of clinical trials
Describe different types of trial designs
Describe different types of controls and interventions
describe 3 types of trial outcomes
What is bias?
Bias is any systematic error in an epidemiologic study that results in an incorrect estimate of the association between exposure and the health outcome. Bias occurs when an estimated association (risk ratio, rate ratio, odds ratio, difference in means, etc.) deviates from the true measure of association.
What is external validity?
External validity is the extent to which you can generalise the findings of a study to other situations, people, settings, and measures.
What is internal validity?
Internal validity is defined as the extent to which the observed results represent the truth in the population we are studying and, thus, are not due to methodological errors.
What is the difference between systematic and random error?
Random error causes one measurement to differ slightly from the next. It comes from unpredictable changes during an experiment. Systematic error always affects measurements the same amount or by the same proportion, provided that a reading is taken the same way each time.
What is selection bias?
Selection bias is a distortion in a measure of association (such as a risk ratio) due to a sample selection that does not accurately reflect the population
Exclusion
Sampling bias
Loss to follow up?
What is sampling bias?
Error that occurs due to using a nonrandom sample
What is information bias?
A flaw in measuring exposure or outcome data that results in different quality or accuracy of information between comparison groups
e.g. misclassification bias, recall bias, reporting bias, interviewer bias, observer bias, measurement bias
Describe the effects of bias regarding the null hypothesis / association
Describe different types of errors
What is the difference between bias and confounding variables
with bias, associations are invalid and purely error
with confounding, associations are real but not causal
what is a confounding variable?
a variable which interferes with the search for causal association between exposure and outcome; masks relationship
Is related both to exposure and outcome
What are the Reddit examples of confounding versus mediating that I found?
“A mediating variable is a variable that explains the relationship between the independent variable and the dependent variable. So, in your example of race and knife crime, poverty being the mediating variable means that poverty correlates with both race and knife crime, and it is a possible reason why there is a link between them.
A confounding variable is a variable that might account for an observation other than what is hypothesized. The example used in my research methods class was that both ice cream sales and drownings increase during the summer months. One might hypothesize that eating ice cream causes people to drown, or that more frequent drownings cause an increase in ice cream sales, but it’s possible that neither of those are the true cause, there could be a thirdconfounding variablethat causes both–people eat more ice cream and go swimming more often during the summer because temperatures are warmer. Confounding variables are things you must think about when you’re forming a hypothesis. They’re alternative explanations for whatever you think you are observing.
Stress in LGBTQIA+ people with mental health issues would be a mediating variable.”
What are methods for reducing confounding variable effects
randomization
restricting
matching
standardization
stratification
multivariate analysis
What is an effect modifier?
Epidemiologists apply the term “effect modification” to indicate that the effect of one variable on another varies across strata of a third. There are many different measures of effect and, thus many different measures by which a variable may be an effect modifier for the relationship between a cause and an effect.
How do we account for effect modifiers?
multivariate analysis
multiple logistic regression & adjusted odds ratios
Examine the statistics for determining a variable a non confounder
Examine the statistics for determining a variable a confounder
How do we interpret when the variable is found to be a confounder statistically?
Examine statistics for effect modification
What are major concepts in ethics for epidemiology?
informed consent
confidentiality
respect for human rights
scientific integrity
What are some examples of well known unethical experiments?
The Tuskegee experiment
Milgram Experiment
Stanford Prison Experiment
Willowbrook Hepatitis Experiment
What are the 3 basic principles of the Belmont Report?
respect for persons
beneficence
justice
What is nonmalfecence?
The balance between risk and benefit
(maximize possible benefits and minimize possible harm)
Review the “slippery slope” of public health practices
Describe the Nuremberg Code of 1946
Describe the Declaration of Human Rights (from United Nations)
Describe the Helsinki Declaration
What are the main elements and uses of descriptive epidemiology?
person / place / time
assessing the health status of a population /
generating hypotheses about causal factors
planning and evaluating public health programs
What are the leading causes of death for various age groups?
Infants: congenital malformations, low birth weight, SIDs
Ages 1-14: unintentional injuries, cancer, congenital anomalies, homicide
Ages 15 to 24: unintentional injuries, mainly motor vehicle accidents
Ages 25 to 44: unintentional injuries, cancer, heart disease
Ages 45 to 64: cancer, heart disease, unintentional injury
Ages 65+: heart disease, cancer, cerebrovascular disease
describe US infant mortality by race
describe the different types of major study designs
describe when to use which study design
What is screening?
The examination of asymptomatic people in order to classify them as likely or unlikely to have the disease.
What is the difference between screening and diagnosis?
While screening occurs in individuals who are asymptomatic, or not suspected of having the disease in question,
Diagnosis is used to confirm whether someone actually has a disease.
What is sensitivity in scree ning?
Refers to the proportion of individuals with the target disease who have a positive test result
What is specificity in screening?
Refers to the proportion of individuals with the target disease who have a negative test result
What is positive predictive value?
The positive predictive value is the proportion of individuals who test positive who actually have the disease, a/(a+b).
What is negative predictive value?
The negative predictive value is the proportion who test negative who don’t have disease d/(c+d).
What are 3 common biases in screening?
detection bias
lead time bias
length bias
What is detection bias?
Detection of a disease precursor by screening in someone who would not ultimately develop symptoms or die from the disease leads to detection bias, or pseudodisease.
Describe lead time bias
Describe length bias
What is test agreement?
In words: kappa is the quotient of the observed proportion of agreement beyond chance and the maximal proportion of agreement beyond chance. A kappa of 0.5 indicates a moderate level of agreement.
What is the value of screening
What are qualities of the perfect screening test
What are principles of screening
What are the following types of screening:
case finding, surveys, early detection
what is surveillance?
what is multiphasic screening?
what is mass versus selective screening?
What are factors in disease causation?
predisposing (create susceptibility)
enabling (environmental conditions)
precipitating (specific or noxious agent, e.g. pollen and asthma attack)
reinforcing (aggravate already established disease)
Describe the web of causation
Describe the pyramid of associations
Define “causal interference”
What are causal pies?
Examine this web of causation for lead poisoning
