Podcast
Questions and Answers
Considering the multifaceted approach to epidemiological study design, which of the following study types would be MOST appropriate for initially investigating a rare and novel disease outbreak with limited resources?
Considering the multifaceted approach to epidemiological study design, which of the following study types would be MOST appropriate for initially investigating a rare and novel disease outbreak with limited resources?
- A cross-sectional study to determine prevalence.
- A prospective cohort study, allowing for longitudinal assessment of disease incidence and risk factors.
- A randomized controlled trial (RCT), providing a high level of evidence for potential interventions.
- A case-control study, enabling efficient examination of prior exposures in affected individuals. (correct)
In assessing the etiology of a newly identified oral malignancy exhibiting a latency period of several decades, what type of study design would MOST effectively mitigate recall bias while still allowing for efficient data collection?
In assessing the etiology of a newly identified oral malignancy exhibiting a latency period of several decades, what type of study design would MOST effectively mitigate recall bias while still allowing for efficient data collection?
- A retrospective cohort study utilizing archived medical records and occupational exposure data. (correct)
- A prospective cohort study initiated two decades prior to the observed increase in malignancy incidence.
- A cross-sectional study design with an ethnographical approach.
- Nested-case control study design using existing cohort data.
Which statement MOST accurately differentiates between the concepts of internal validity and external validity in the context of epidemiological research?
Which statement MOST accurately differentiates between the concepts of internal validity and external validity in the context of epidemiological research?
- External validity is a prerequisite for internal validity.
- Internal validity concerns the generalizability of study findings to other populations, while external validity focuses on the accuracy of findings within the study sample.
- Internal validity assesses the degree to which the study design minimizes confounding, while external validity evaluates the ethical implications of the research.
- Internal validity is a prerequisite for external validity. (correct)
When designing a community-based intervention to reduce sugar-sweetened beverage consumption, which sampling method would BEST ensure representation from various socioeconomic strata, assuming limited prior data on the population's distribution?
When designing a community-based intervention to reduce sugar-sweetened beverage consumption, which sampling method would BEST ensure representation from various socioeconomic strata, assuming limited prior data on the population's distribution?
During a clinical trial for a novel drug targeting periodontitis, the statistician becomes aware of the treatment allocation for each participant. According to the principles outlined regarding blinding in research, what specific type of blinding has been compromised?
During a clinical trial for a novel drug targeting periodontitis, the statistician becomes aware of the treatment allocation for each participant. According to the principles outlined regarding blinding in research, what specific type of blinding has been compromised?
In the context of Hill’s criteria for causal inference, which consideration is MOST challenged when assessing the relationship between ambient air pollution and the incidence of respiratory disease in a highly industrialized area with numerous potential confounders?
In the context of Hill’s criteria for causal inference, which consideration is MOST challenged when assessing the relationship between ambient air pollution and the incidence of respiratory disease in a highly industrialized area with numerous potential confounders?
In a scenario where early epidemiological investigations erroneously conclude that a specific brand of dental floss is associated with an elevated risk of gingivitis due to inadequate adjustment for socioeconomic factors and oral hygiene practices, which type of bias is MOST likely present?
In a scenario where early epidemiological investigations erroneously conclude that a specific brand of dental floss is associated with an elevated risk of gingivitis due to inadequate adjustment for socioeconomic factors and oral hygiene practices, which type of bias is MOST likely present?
Assuming a scenario where the implementation of a national fluoridation program shows a reduction in dental caries. What would MOST strengthen the inference that the intervention is causally related to the observed outcome?
Assuming a scenario where the implementation of a national fluoridation program shows a reduction in dental caries. What would MOST strengthen the inference that the intervention is causally related to the observed outcome?
A researcher aims to evaluate the effectiveness of a community-based program to promote oral health. What aspect would MOST critically determine the program's effectiveness?
A researcher aims to evaluate the effectiveness of a community-based program to promote oral health. What aspect would MOST critically determine the program's effectiveness?
What statement is MOST accurate when describing confounding variables?
What statement is MOST accurate when describing confounding variables?
Given the framework of Rothman's causal pies, which statement is MOST accurate regarding the concept of a 'necessary cause'?
Given the framework of Rothman's causal pies, which statement is MOST accurate regarding the concept of a 'necessary cause'?
In comparing efficacy versus effectiveness trials, which statement is MOST accurate?
In comparing efficacy versus effectiveness trials, which statement is MOST accurate?
Assuming a scenario where an observational study erroneously links the use of electric toothbrushes to an elevated risk of oral cancer due to participants with poor oral health are more likely to use electric toothbrushes in an attempt to improve their oral hygiene. What describes the observed association?
Assuming a scenario where an observational study erroneously links the use of electric toothbrushes to an elevated risk of oral cancer due to participants with poor oral health are more likely to use electric toothbrushes in an attempt to improve their oral hygiene. What describes the observed association?
In a study designed to assess the effect of sugar-sweetened beverages on childhood obesity, researchers opt to control for physical activity levels by only including children who engage in a fixed amount of exercise per week. According to the terminology, which approach is BEST described?
In a study designed to assess the effect of sugar-sweetened beverages on childhood obesity, researchers opt to control for physical activity levels by only including children who engage in a fixed amount of exercise per week. According to the terminology, which approach is BEST described?
What is the MOST appropriate method to address interviewer bias?
What is the MOST appropriate method to address interviewer bias?
What is the purpose of applying Hill's causality criteria?
What is the purpose of applying Hill's causality criteria?
A research team discovers that individuals highly susceptible to dental caries are also more likely to participate in oral health studies. According to the data, why does selection bias become a particular concern for extrapolating research findings?
A research team discovers that individuals highly susceptible to dental caries are also more likely to participate in oral health studies. According to the data, why does selection bias become a particular concern for extrapolating research findings?
Which BEST describes Snowball sampling?
Which BEST describes Snowball sampling?
What's the BEST scenario to use a Case-Control study?
What's the BEST scenario to use a Case-Control study?
To address a study affected by confounding, why would standardization be useful?
To address a study affected by confounding, why would standardization be useful?
Which of the following is NOT typically used to examine causality?
Which of the following is NOT typically used to examine causality?
When are recall bias and selection bias most relevant to epidemiology?
When are recall bias and selection bias most relevant to epidemiology?
Which of the following is NOT a factor related to the causation of a disease?
Which of the following is NOT a factor related to the causation of a disease?
Unlike physicians who study disease in individuals, epidemiologists study disease in groups of people, or populations. Where physicians address specifics, focusing on the uniqueness of each patient, epidemiologists focus on what is common and general about members of populations, inferring principles that apply to _____ , if not all, of the study subjects.
Unlike physicians who study disease in individuals, epidemiologists study disease in groups of people, or populations. Where physicians address specifics, focusing on the uniqueness of each patient, epidemiologists focus on what is common and general about members of populations, inferring principles that apply to _____ , if not all, of the study subjects.
When assessing existing cases, or the prevalence rate, you would MOST likely use a _______?
When assessing existing cases, or the prevalence rate, you would MOST likely use a _______?
In the study of disease, what does 'pattern' refer to?
In the study of disease, what does 'pattern' refer to?
What would one call something affecting the validity of a clinical trial?
What would one call something affecting the validity of a clinical trial?
Which of Hill's Criteria is difficult to address using only observational studies?
Which of Hill's Criteria is difficult to address using only observational studies?
Flashcards
What is Epidemiology?
What is Epidemiology?
The study of the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.
Purpose of Epidemiology?
Purpose of Epidemiology?
To better understand the burden and causes of health problems in human populations and to make changes that decrease risk and improve health.
Who was John Snow?
Who was John Snow?
A British physician considered a founder of epidemiology, who identified the water pump as the source of a cholera outbreak in 1854.
Frequency vs Pattern in Epidemiology
Frequency vs Pattern in Epidemiology
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Determinants
Determinants
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Epidemiological Triangle
Epidemiological Triangle
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Biological Agents in Epidemiology
Biological Agents in Epidemiology
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Chemical Agents in Epidemiology
Chemical Agents in Epidemiology
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Physical Agents in Epidemiology
Physical Agents in Epidemiology
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Environment in Epidemiology
Environment in Epidemiology
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Endemic
Endemic
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Epidemic
Epidemic
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Pandemic
Pandemic
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Mortality
Mortality
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Morbidity
Morbidity
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Risk Factor
Risk Factor
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Descriptive Epidemiology
Descriptive Epidemiology
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Explain (Epidemiology)
Explain (Epidemiology)
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Predict (Epidemiology)
Predict (Epidemiology)
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Control (Epidemiology)
Control (Epidemiology)
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Observational Studies
Observational Studies
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Experimental Studies
Experimental Studies
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Cross-Sectional Study
Cross-Sectional Study
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Longitudinal Study
Longitudinal Study
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Case-Control Study
Case-Control Study
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Cohort Study
Cohort Study
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Clinical Trial Factors
Clinical Trial Factors
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Comparitive (RCT)
Comparitive (RCT)
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Sampling benefits
Sampling benefits
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Simple random sampling
Simple random sampling
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Study Notes
- Epidemiology studies the distribution and determinants of health-related states or events in specified populations, and the application of this study to the control of health problems.
- Epidemiology is derived from Greek words: "epi" (on, upon), "demos" (people), and "logy" (study).
Definitions of Epidemiology
- The study of health in human populations
- The study of how disease is distributed in populations and the factors that influence or determine this distribution
Purpose of Epidemiology
- To better understand the burden and causes of health problems in human populations
- To make changes that decrease risk and improve health
Historical Background: John Snow
- John Snow (1813-1858) is considered one of the founders of epidemiology.
- He identified a water pump in Broad Street as the source of a cholera outbreak in 1854, after plotting cases on a map.
Key Concepts: The 3 D's
- Epidemiology is concerned with the distribution and determinants of diseases (3 D's).
- Distribution refers to the frequency and pattern of health events in a population.
- Frequency is the number of health events in relation to the population size.
- Pattern refers to the occurrence of health-related events by time, place, and person.
- Determinants are factors or events capable of bringing about a change in health e.g. infectious agents and genetics
Epidemiology Questions
- What is the event (problem)?
- What is the magnitude?
- Where did it happen?
- When did it happen?
- Who were affected?
- Why did it happen?
- How did it happen?
Epidemiological Triangle
- A model used for studying health problems, consisting of three corners (vertices).
- Agent: The microbe or factor causing the disease.
- Host: The organism harboring the disease.
- Environment: External factors that cause or allow disease transmission.
- The mission of an epidemiologist is to break at least one side of the triangle to stop disease.
The Agent ("What")
- The agent is the cause of the disease.
- Biological agents: Bacteria, viruses, fungi, allergy or nutrients e.g. S mutans
- Chemical agents: Chemical toxins such as lead, dust, medication, or fluoride e.g. fluorosis
- Physical agents: Radiation, heat, cold, or trauma
The Host ("Who")
- A susceptible human or animal who harbors and nourishes a disease-causing agent.
- Host susceptibility depends on age, sex, race, genetic influence, response to stress, lifestyle, and immunization history.
The Environment ("Where")
- Aggregate of all external conditions and influences affecting life and development.
- Physical environment: Geography, climate, weather, water, air and soiled (fluoride content, high temperature).
- Biological environment: Diet and nutrition, presence of animals/plants/insects, and protein/vitamin deficiency.
- Social environment: Education, occupation, social conditions, and their impact on general health.
Time
- Time is in the center of the Epidemiological Triangle
- Time describes the time between infection and symptoms (incubation).
Epidemiological Terms
- Endemic: Constant presence of a disease affecting population in a definite area e.g. Malaria
- Epidemic: Unusual occurrence of a disease in any region
- Pandemic: Disease affecting a large number of the population worldwide
- Mortality: Death rate (# deaths / # population)
- Morbidity: # diseased / # population
Vital Indicators
- Prevalence: Existing cases of a disease at a designated time.
- Incidence: Number of new cases.
- Prevalence Rate: # Current cases / Population at risk.
- Incidence Rate: # New cases / Population at risk.
- Susceptibility: Being at risk of becoming a case.
- Risk Factor: Exposure statistically related to an outcome e.g. smoking for periodontitis
Risk Factor Criteria
- Disease frequency varies with exposure
- Exposure precedes disease onset
- Risk factor can be modifiable or unmodifiable
Scope of Epidemiology
- Describe: Describes the health status of populations
- Explain: Explains disease etioloy, identifies causal factors, and determines modes of transmission
- Predict: Predicts disease occurance by estimating cases and distribution
Controlling Disease
- Control: Prevents new cases, eradicates existing cases, and prolongs lives of those affected
Uses of Epidemiology
- Study the history of health populations
- Diagnose community health.
- Study health services and improve them
- Estimate individual risks
- Identify syndromes
- Completes the clinical picture of diseases
- Searches for causes of health and disease
Types of Epidemiological Studies
- Observational: Investigator measures but does not intervene.
- Experimental: Active attempt to change a disease determinant.
Observational Studies
- Descriptive: Describes the occurrence of a disease in a population.
- Analytical: Analyzes relationships between health status and other variables.
Experimental Studies
- Involves active attempt to change a disease determinant such as exposure or a specific behaviour.
Descriptive Studies
- Studies one group to describe health outcomes, frequency, and distribution etc.
Descriptive vs. Analytic Epidemiology
- Descriptive answers: who, what, when, and where.
- Analytic answers: why and how.
Cross-Sectional Studies
- Assesses health and exposure status simultaneously (snapshot) and is a prevalence study.
- Advantage: Easy to conduct.
- Disadvantage: Cannot infer cause.
Characteristics of Cross Sectional Studies
- Indicates existing cases/prevalence.
- Describes disease distribution.
- Simple and inexpensive
- Takes short time
Disadvantages of Cross Sectional Studies
- Temporal sequence cannot be established.
- Does not allow for changes over time, cannot accommodate disease that take time to develop.
Longitudinal Studies
- Repeated examination of the same population.
- Indicates new cases (incidence rate).
- Describes disease history and identifies risk factors
Disadvantages of Longitudinal Studies
- Time consuming
Analytical Epidemiology
- Explains the relationship between risk factors and outcome (disease).
- Includes Case-Control (retrospective) and Cohort studies (prospective).
Case-Control Study
- Investigates prior exposure of those with and without a condition.
- Allows us to study rare health outcomes without following thousands of people, quicker, cheaper and easier.
Case-Control Characteristics
- Assessing existing disease relationship to other variables
- Identifying those with (cases) and without the outcome (controls).
- Retrospective.
- Used for rare health outcomes.
Disadvantages of Case-Control Studies
- Greater potential for bias which includes selection and recall bias
Bias
- Favortism in choosing study subjects
- Must recruit subjects uniformly and accurately
- Selection bias: Not everyone can be selected that is eligible and these people may be systematically different
- Recall bias: Cases and controls recall exposures differently
Cohort Study
- Follows healthy people with varying exposure levels over time.
- Exposure precedes health outcome
- Less subject to bias as exposure is evaluated before health status is known.
Cohort Characteristics
- Can assessing multiple outcomes
- Suitable for rare exposure
- Can estimate incidence rate
- Most useful for relatively common diseases
Historical Cohort Studies
- Retrospective follow up to evaluate past exposure.
Experimental Epidemiology
- Intervention or experimentation involves attempting to change a variable in one or more groups of people, such as eliminating a dietary factor or testing a new treatment
Clinical Trials
- Procedures in medical research assess safety and efficacy, planned experiment in humans assesses the efficacy and safety of interventions in a similar group without intervention
Effectiveness vs. Efficacy Trials
- Efficacy trials test if a treatment works
- Effectiveness trials test how it works in everyday conditions.
Types of Clinical Trials
- Treatment, Prevention, Diagnostic, Screening, Quality of life
Randomized Controlled Trials (RCTs)
- An epidemiological experiment where subjects are randomly allocated to study and control groups to see receiving or not receiving an intervention
Key Aspects of Randomized Controlled Trials
- Ensure groups are compared appropriately
- Initial selection and randomization is done properly
Validity Factors in a Clinical Trial
- Random allocation
- Use of control
- Blind concept
- Adequate number of subjects
- Duration and consistency in diagnosis
Random Allocation
- Each subject having equal chance of being in either test or control group.
Control
- The use of a comparison group which is not exposed to the factor under study
Blinding
- Blinding is when subjects or the experimenters dont know what groups have the factor
Blind Types
- No knowing treatment allocated prevents influence and error which include single, double and tertiary
Blind Definitions
- Single Blind: participants unaware to what group they assigned
- Double blind: participants and investigator are unaware of groups
- Tertiary blind: The statistician is not aware
Duartion of Trials
- Duration should be long enough for new detections
Consistency
- Consistency or Reliability, extent to which results can be reproduced
Reliability types for examiners
- Intra-examiner: Ability of examiner to record some conditions the same way over time
- Inter-examiner: The reliability between different examiners
Advantages of RCT
- Comparative: treatment compared to another
- Minimizes Bias: Randomization minimizes allocation and selection bias
- Blinding- Minimizes performance bias
- Groups comparable to knwon factors
- Statistically reliable
Disadvantages of RCT
- Vast sample sizes
- Allocation predictable
- Longer duration and more expensive
- Do not mimic real life situation
- Ethical limitations
Sampling in Epidemiology
- Method that infer information to population
- Small number or sample must be chosen from population
Methods
- Simple random, stratified random, systematic, cluster, convenience and Snowball
Simple Random Sampling
- Each inidvidual chosen by chance
- Used small population
Stratified Sampling
- Divided into subgroups who share simialr characterstics
- Suitable for heterogenous polulation
Systematic Sampling
- Select at regular intervals from all of polulation
- Saving time and low cost
Cluster Sampling
- Use subgroup of polulation as sampling unit rather than individuals.
Convenience Sampling
- Easiest sampling where volunteers allowed to take part in stuy.
Snowball Sampling
- Subject asked to nominate further subjects known to them and sample increase
Sample Size
- More precise estimates result from a larger sample size
Factors of Sample Size
- Level of precisions
- Homgeneity
- Prior information
- Resources, time and cost
- Samplign procedure
Biad and Confounding
- Goal of epidemiological studies detemrining relationship between exposure and disease
Biad
- Bias is erroed commited by invenstigaor
Confounding
- Reflecting fact that epidemiolgoical reseaerach is concucted among free living humans with unevenly distributed characterstics
Types of Bias
- Selection bias
- Information or measumebt bias
- Confounding
Selection Biad
- Subject in study are not truly represtnaive
- Volunteers alway have bais
Measurement bias
- Individual measument are innacruate due not correclty mearsing.
Recall Bias
- Measurment bias importanctive case control studies
Observer Biad
- Invetgiator or lobatory tech know that exporse staatus know how to influence
Insturment Biad
- Measuring insuetmnet not properly calibarted
Confounding
- Exposrue exisits and is assocaisd what bot disase and exposrue stufidied
Confounding difficile
- Mix it togetehr can not mix
Control contouding
- Rand, rest, match
Rand
- Potianll coinfound vareibel eauy distribteud between groups big sampple siZe
Validitiy
- To which test is capable of meausirng
Internal validity
- Desgree of resultat are correct of people
External validity
- General to which reslat a
Causation VS assocaiton
- Majoir focus is diseas e prto prevent and conrt
Risk
- Prbablty that spciif event occur
Casue
- EVnet conditon charctersitic that important
Cause Types
- Sufficien, neces
Sufifcen
- CAue is term that inevtaly iniciate
Facotrs of Causation
- PRedisposing - factorss such ad ge
- Enableing - loow icnomem
- Precipiatiting - xopuse tpsicifdisese
- Renforcign- Repaet exporsue
CAusatiuon Versus association
- Eitlogy is hard to deerer Many experse Caser May differ
Assocate
- Assocaite and it
Hills CAusaiton
- Temp sequence
- Conisnsy
- DEose Respoe
- Biiilicaly plu
- Cohoerent Facotr Spefis
Teamp Sepa
- MuST COME BEfre
PLsuably and cer
- MEch can
Strength
- MOer is causal
Dose Resp
- Big Exopoer big effect
Study Design
- ABiliy of casuin
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