Research Exam 2 PPT 3 and PPT 4 Flashcards
Descriptive observational study
Designed to describe the distribution between two or more variables without regards of hypothesis or any causal
-Not one clinical/epidemiology study can answer the research question definetly
-Information is collected routinely so less time consuming
-Essential for formulation hypothesis/research question
Case report
Single patient
Case series
Series of patient
Case report and case series
Observational descriptive study design the most basic
-Make link between clinical medicine and epidemiology of the disease
-Chance of observation may open a new line of investigation
Cross sectional studies
Observational descriptive study
-Measures the association of the outcome and the exposure within a population using a specific target time point
-Helpful in assessing the disease burdern and the healthcare needs
-Useful to estimate the prevalence of the disease and the exposure
Observational Analytical study
Designed to perform Hypothesis testing to establish association between the outcome and the exposure
-Is comparison of groups
-Timing sequece
-Observational - Case control studies, cohort studies
-Interventional (Experimental)-Randomize control trials
Cohort
Based on the exposure
It can be prospective or retrospective
Case control
Based on the outcome
Is retrospective
Prospective
Record information before the outcome occur
“Will follow patients for 5 years and recorded the incedence in both groups”
Retrospective
Collect data after exposure occur
An observational study is being conducted in 2023 to investigate whether vasopresssin increases the risk of venous thromboembolism (VTE) among critically ill patients. The investigators sampled patients who were hospitalized in the ICU from 2020-2022 and obtained two groups: one group who were treated with vasopressin and another group who were not treated with vasopressin. The investigators then recorded whether patients in each group developed VTE during their hospitlization.
Which of the following best describes this study?
A) Retrospective cohort study
B) Nested case-control study
C) Traditional case-control study
D) Prospective cohort study
A) Retrospective cohort study
Selecting cohorts
1-Type of exposure being investigated
2-Frequency of exposure in the population
3-Accesibility of pt
-Pt should be free of the outcome at the start of the study in order to establish temporal relationship between exposure and outcome
-Divided into exposed and unexposed
-Measurement of exposure is based on Variability, Intensity, regularity, duration
-At the start both exposed and unexposed should have the equal chance of developing the outcome-Counterfactual idea
Folow up in cohort studies
Frequency of examination and duration needs to be follow up but is based on the exposure and outcome of interest
-Need to follow up both group on the same time
-Concern on loss-to-follows up usually in long term studies
Cohort studies pros
-Incidence data is available
-Establish temporal relation
-Study mutliple outcomes
-Study rare exposures
Cohort studies cons
-Expensive more time consuming than case control
-Loss to follow up
-Large sample size
-Cannot study rare outcomes
Case control study step 1
Select cases that are the patients that have the disease the outcome based on case definition
Case control study step 2
Select the controls
-Pt that dont have the disease (outcome)
-They are selected from the population that gave rise to the cases
-They are independent of the exposure
Case control study pros
-Less time consuming and inexpensive
-Smaller sample size
-Can study multiple exposule
-Can study rare outcomes
-Efficient for long term
Case control study cons
-Cannot establish relation
-Difficult to identify controls
-Cannot study rare exposures
-Cannot predict incidance rate and prevalence
-Cannot calculate RR and RD only OR
Nested case-control studies
A cohort study need to happend they are exposed then alot of time need to pass and if they have the disease they will be cases and if they dont have the disease they are controls
-The controls are selected from the cohort/target population that gave rise to the cases
-More time consuming cause uses a cohort study first than time needs to pass and get a case control studie
-OR is the measurement
-Disadvantage- more time consuming and less stregnth of evidence than cohort study
Experimental study designs
Study design that is used to compare the benefits of a intervention with treatment or no treatment is used to see the cause and effects
-Is prospectives subjects are place in a study group and then follow up over time
-Randomize controlled trial
-Quasi experimental non random trial
Randomized controlled trials
-Is a prospective study design compares the efficacy and effectiveness of a drug compared with the control group
-Done in human
-Gold standard for study design
-Is used for causation
-Has randomization, blindness, control group
Efficacy trials
Compares the new drug with the comparator (the placebo) under ideal setting
-Homogenous population
Effectiveness (Pragmatic) Trials
Compares the new drug with the comparator that is the usual care under REAL WORLD CONDITIONS
-Heterogenous population
Concurrengt/Parallel design
a RCT design
-The most common RCT design
-Participants are assigned a group treatment and stayed in the same group throughout the study
Crossover design a RCT
-Participants are randomily assigned to either the intervention group (exposure to drug) or the comparator (placebo) and then they will switch groups
- A CARRY OVER EFFECT needs to happen- that is a washout period not give any drug to prevent residual effect
-PERIOD EFFECT- is a stable disease and it provided byster
Factorial design a RCT
Asseses multiple intervention in the same study
-So 2 interventions 4 possible combinations
-Has synergy that his potential for combining
-Drug A + Placebo
-Drug B+ Placebo
-Drug A + Drug B
-Placebo + Placebo
And the pts are randomize to the different groups
RCT Design: Randomization
-Assigment of participants to the intervention group or comparation group placebo they have a equal chance of being selected
-Need to ensure similar characteristics in both groups
-Want to see the cause and effect of the treatment
-Randomization allows investigators to get close to counterfactual ideal
Simple randomization
Uses a random number generator to allocate the pts in the different groups
-Easiest approach to randomization but small sample size cause unequal number of participants in each group
Block randomization
Ensure the same number of participants in the treatment group and control group
-The participants are randomly divided into blocks and then the investigator randomly select a block for the study
Stratified randomization
Participants are divided into different strata based on specific characteristics and then they are randomly selected from each strata into a treatment group
-Ensure certain baseline characteristics are equal between the treatment groups
In a randomized controlled trial assessing the effectiveness of a new anxiety medication, the researchers want to ensure that history of depression at baseline are evenly distributed between the two treatment groups. Which randomization technique would best address this concern in the given scenario?
A) Cluster randomization
B) Block randomization
C) Simple randomization
D)Stratified randomization
D) Stratified randomization
Cluster randomization
Specific groups (clusters) are randomize selected into a treatment group
Each subject in the cluster will receive the same treamnt
-Clusters can be: clinics, highschools, community, villages
-Useful for measuring the effect of the intervention in an entire community
Open label
When blinding is impossible or unethical
The participant, investigator and data analysist know what they are taking
Single blinded
Only the participant dont know what they are taking but the investigator and data analysis knows
Double blinded
When the participant and the investigator dont know what they are taking but the data analysis do know
Triple blinded
neither of the three participant, investigator and data analysis knows what they are taking
RTC Design: Run In Period
-Is prior the trial start is remove all ineligible pts and non compliant pts
-Sometimes used as a carry over period (a wash out period) for pt to stop taking any medication prior to the trial
Role of run in period
Ensure pt compliance and adherence
Minimize placebo effect
Ensure drug response
The purpose of the run-in period in a randomized controlled trial is to:
A) Ensure compliance to treatment
B) Overestimate the drug benefits
C) Maximize placebo effect
D) Underestimate the risks of treatment
A) ensure compliance of the treatment
Intention to treat ITT
Analyze all pt in both groups regardless if failed to follow up or took placebo when they shouldn’t
-try to preserve randomization
Suppose a clinical trial randomly assigned 150 patients to receive either drug A (n=75) or placebo (n=75). At the end of the study, the researchers had the following results: in the drug A group, 70 were on drug A and 5 were on placebo; and in the placebo group, 72 were on placebo and 3 were on drug A. The investigators decide to analyze the study to include all patients as randomized, regardless of the treatment at the study end. Which of the following best describes this type of analysis?
A)Per-protocol
B)As-treated
C) Intention-to-treat
C) Intention to treat
Per protocol (PP) or on treatment
Only analyze pt that took what they needed to take
-Does not take into consideration Loss of follow up or cross over
-Randomization is not preserve
-Is useful for analyzing AE
As treated AT
At the end of the study the 3 pt that took placebo in the drug group will be analyze as the placebo group
-Randomization is not preserve
-Cross over and Loss of follow up is a concern
Kaplan meier analysis
Summarizes the probability of survival over time
-It analyzes using log-rank test
-Compares the overall survival between the groups with respect to the study outcome
Randomize control trial pros
Reach counterfactual ideal
-Provide causal evidence
-More control over measurments
Randomize control trial cons
-More expensive and time consuming
-Cannot be measure in all conditions due to ethical reasons
Quasi Experimental study design
Lack of randomization
-Is used to analyze a new implemented program or policy
History effect
Some event other than the intervention occur during the time frame that is causing the observe change
Maturation effect
Participant change their way of study and learning throughout the research
Regression toward the mean
natural variation of repeated data look like real change
Interrupted time series design
Uses multiple observations before and after the intervention, during a specific time frame
-See a change in the antibiotic use after the implementation of a new hospital policy
An investigator is interested in investigating the implementation of a hospital policy to restrict the use of opioids using an algorithm. The investigators want to measure whether a change in the reduction in adverse events ocurred before and after the policy implementation. Which of the following studies would be the most appropriate to conduct this study?
A) Interrupted time series
B) One group pre-test post-test
C) Cohort study
D) Randomized controlled trial
A) interrupted time series
