lecture 6: RCT Flashcards
what are the types study designs under experimental studies th
RCT
cross over
quasi-experimental
single-subject
true or false:Rct is the ideal design for evaluating both efficacy and effectiveness of a treatment
truewh
what is the major advantage of RCT over observational
ability to demonstrate causality
where do RCT rank in the levels of evidence
1a) systematic review of RCTS
1B) individual RCT with narrow confidence intevential
2b) low quality act with loss to follow up
what would make an RCT level 1b
narrow confidence interval (not much variability in results), not a lot of loss to follow up
what are some reasons you would have a low quality RCT
wide CI
loss to follow uo
randomization issues
true or false: RCTS are retrospective and experimental
false, they are prospective and experimental
what does it mean that an RCT is a prospective and experimental study
starts at a point in time and progresses foreard
the intevention/IV is controlled by the investigator
true or false: RCTS are usually comparative studies
true
the comparison group[ is an RCT is aka
control group
what is the basic design model of an RCT
CONSORT diagram
explain the consort diagram
Start with population of interest and use an eligibility criteria to establish who is eligible/non elig (excluded).
The eligible people will be contacted to engage in the study (recruitment) and a part of them will decline to participate (not part of the study even tho they are eligible). The sample of the study will only include those who agred to participate and signed the informed consent.
Then we have the randomization (most important feature of the RCT because it controls for potential counfounders) into eather the intervention or the control group/usual standard of care/no intervention (all depends on the ethics).
Groups are followed over time to see if there is any difference between the groups (look to see if there is a mean difference in the effect on that particular outcome of interest)
why may RCTs be difficult in terms of ethics
RCTS can be challenging for ethical aspects (hard to convince people to be part of a control etc) that is why many of the studies are quasiexpreimental
what is a quasi experimental study
in a quasi-experimental study, the researcher still manipulates an independent variable but does not have full control over some aspects of the study such as no randomization, sometimes no control group (only intervention)
where does RCT fit in the research cycle
they establish efficacy. effectiveness and efficiency
where does cohort fit in the research cycle
mecs and associations
where does case control fit in the research cycle
mec and assocaiton
where does cross-sectional fit in the research cycle
burden of disease
what is the def of efficacy
refers to the ability of an intervention to produce a desirable effect under ideal/controlled conditions
what is the def of effectiveness
refers to the ability of an intervention to produce a desirable effect in the real world setting/clinical practice
what is a a reason that you might have 100% efficacy in the lab but only 50% effectiveness in the health setting
because in the real world you have many factors that influence outcomes effect such as access to care, how many people to deliver the care, instrucments etc)
efficiency is done with ideal circumstances, perfect compliance, adherence to protocols, and use per protocol analysis, this differs from effectiveness trials that have real world circumstances, compliance is self determined and protocol violations may occur
true or false: if a study has 100% efficacy and 100% effectiveness, that means we will automatically implement it as a treatment and explain
false, it is not just about having the presence of an effect but also about the efficiency and resources. For a study to be implemented it must also have optimal use of ressoruecs such as (time, money, feasibility etc)
what are the 5 main features of an efficacy trial
ideal circumcanstances
perfect subject compliance
no protocol violation
endpoints on all data
per protocol analysis
what are the 5 main features of an effectiveness trial
real world circumcanstances
compliance self -determiend
protocol violations may occur
missing data
intention to treat analysis missing data inputed
what does it mean for an efficacy trial to have ideal circumstances
This refers to conducting the trial under optimal conditions that maximize the likelihood of observing the effects of the intervention being tested (standardized measures, controlled environments and controlled confounding variables)
what does it mean for an efficacy trial to have perfect subject compliance and no protocol violation
Subject compliance refers to the extent to which participants adhere to the study protocol, including following instructions, taking medications as prescribed, attending follow-up appointments, etc. In an efficacy trial with perfect subject compliance, every participant would strictly adhere to the protocol without deviation
what is a per-protocol analysis in efficacy trials
Per protocol analysis involves analyzing only the data from participants who strictly adhered to the study protocol, excluding those who deviated or dropped out.
what does it mean for an effectiveness trial to have real-world circumstances circumstances
Real-world circumstances also include factors such as variations in healthcare delivery, resource availability, and patient-provider interactions that can influence treatment outcomes.
what does it mean for an effectiveness trial to have compliance self-determined
Unlike efficacy trials where subject compliance is closely monitored and often enforced, participants in effectiveness trials have more autonomy in determining their level of compliance with the intervention.
what are some reasons for missing data in effectiveness trials
participant dropout, loss to follow-up, or incomplete data collection.
what is intention to treat analysis
participants are analyzed based on their initial treatment assignment, regardless of whether they actually received the treatment or not.
This approach is simple and important because it helps maintain the integrity of the randomized treatment assignment
why is intention to treat anaylsis important in RCTS
This approach is simple and important because it helps maintain the integrity of the randomized treatment assignment (if you just excluded the data, the sample could potentially be biased./not representative_
how do you read an RCT
research question
consort diagram
demographic tables
results tables
how are the results tables usually represented in RCTS
p values, CI, effect size
in an RCT, If the study’s aim is to provide evidence the question must be BLANK
specific as to what evidence is needed
what are some of the questions that should be answered by the RCT research question
PICOT :
Who should be studied?
What should the intervention be?
What should the comparator be?
What should the outcome be?
When should the outcome be measured?
know the table for the PICOT model in RCTS
what is the consort diagram
flow diagram displaying the process of all participants through the trial
the consort diagram is a useful tool for detecting what type of bias
selection bias
know the important elements of a consort diagram
in the consort diagram, you see that the sample size in the intervention group is 44. They then lose 4 people to follow up, but the analyzed sample is still 44. What does the mean/what analysis did they use
intention to treat analysis (did not exclude the missing data)
true or false: efficacy trials will ONLY use per protocol analysis
false, they normally use that but sometimes will use the intention to treat because realistically people can drip out and the intention to treat protocol will maintain the prognostic balance that the randomization provides
true or false; demographics table is done at baseline
false
what are some things to look for in the demographics table
look for baseline similarities between groups (want the groups to have no statistically significant differences in their characteristics)
-look at p values
what are the 3 main important results i the results table
p value
CI
effect size
what is the CI (give example of what a 95% CI means
a reliability interval estimate that suggests the range of outcome results when the analysis is repeated
ex:With similar study samples, we would expect that the mean value difference b/w the groups would lie anywhere between the CI boundaries 95 out of 100 times.
what does a p value of 0.05 indicate
there is a 5% chance that the results are due to chance and not the effect of treatment
true or false: the p value tells you how much better the intervention is when compared to the control…
false, it does not
if a value is statistically significant, then it is also clinically significant
false,
is p value influenced by sample size and explain
yes
With a sufficiently large sample, a statistical test will almost always demonstrate a significant difference Because larger sample sizes enable us to/more powerful to detect even small differences between the groups
what is a benefit/advantage of the CI in terms of comparing it to ur intervention
95% CI allows you to see the change of the intervention in the units of the measured variable (same unit as the outcome measure units) which helps determine significance clinically
a result is not statistically significant if the CI includes what
null value
in an RCT, a result is not statistically significant if the CI includes…
0
in an case control and cohort, a result is not statistically significant if the CI includes…
1
why is the null value for an RCT 0 and not 1
null value is 0 because we are looking at a difference in means between a control and intervention group
what does the size of the CI deepen on
sample size and standard deviation
explain the effect of a large sample size on CI
Large N = “more confidence/precision” = narrower CI
explain the effect of a smalll sample size on CI
Small N = “less confidence/precision” = wider CI
what does the effective size measure
the magnitude of a difference in mean between treatment and control groups
Independent of sample size
0.2-0.4 is a small, moderate or strong/large effect size
small
0.5-0.7 is a small, moderate or strong/large effect size
moderal
0.8 and above i a small, moderate or strong/large effect size
large
what would be a large cohend d effect size
0.8 and above
what would be a moderate cohend d effect size
0.5-0.7
what would be a smal cohend d effect size
0.2-0.4
what is the between group comparison of a study (CHAT GPT and notes)
Between-group comparison in studies involves comparing two groups (intervention and control) to evaluate differences in outcomes of interest/efficacy of intervention
what is the within group comparison of a study (CHAT GPT and notes)
Within group comparison is used to determine the change in the outcome of interest within 1 group
what dopes CMC mean
clinical meaningful change :
refers to the degree of change in a measured outcome that is considered significant or relevant from a practical/clinical standpoint,
basic form for interpreting CI and mean change
-comment on true mean change between groups (name the groups, the unit and the CI)
-state what the CI means in words
-mention if the CI is statistically significant/and or clinically significant
-mention if the confidence interval is narrow/wide and pqrescicion deepening on clinical relevance.
-make a conclusion about the results of the the study/intevention
