Week 2. Flashcards
Types of clinical information needs that can be answered using research ?
The clinical information needed maybe related to
-Local info like background
These cannot be answered by research.
General information like:
- aetiology or frequency
- prognosis
- diagnosis
-treatment
-Patient concerns and experiences.
These can be answered by research.
Just in case information
Also called PUSH information
Information that is out there in the form of journals, newsletters, textbooks, social media, chats between professionals.
This is targeted for professionals, when information should reach them.
This can be done by readingthe abstract, see if it is of interest and then read the full thing and store it for later.
Best to gather such information from reliable good abstracting journals. (Like advertisements are published journals)s
Just in time information
This is information that potential customers look for. They don’t wait for information to be pushed to them. These are information that health professionals look for.
Different study types
Cohort
Case - control
Surveys
Cross - sectional
Randomised Cast Trials.
Qualitative
Case - series
Hierarchy of evidence?
There is no hierarchy of study as such to gather evidence in general.
But there is hierarchy of evidence for each type of questions.
Hierarchies of evidence helps us in deciding what study provides the best evidence and therefore what to look for first.
Best study to find information on risk factors
Cohort (retrospective)
CAS - control study
Prevalence of a condition - best study type to find information
Cross - sectional survey
Study for diagnosis questions
Cross - sectional study
Cohort - to test diagnostic alternatives
Best evidence for any type of information
Systemic review or meta analysis
Best study for intervention questions
RCTs
Best study for prognostic questions
Prospective cohort study
Bias?
Bias is a systemic error in the way that participants are selected for a study, outcomes are measured or data are analysed. Each of these can lead to inaccurate results.
One of the main steps on internally validity checking.
(Anything that affects the study from being true)
Types of bias
- Selection bias / sampling bias - the sample will not represent the true population
- Allocation bias - bias in how intervention and selection is allocated
- Maturation bias - changes that might have occurred naturally over time.
- Attrition bias - participants may withdraw or loose participants from one group more than the other.
- Measurement bias in experimental studies - difference in the way things are measured between the groups.
- Placebo effect
- Hawthorne effect - participants may experience changes due to the attention they are receive in during the research process.
Confounding
Confounding factors are those that cause not error in the measurement but error in the interpretation of the result.
How to reduce confounding?
- randomisation
Probability or P
The probability of the difference between the two groups is by chance alone and not due to other factors or confounders.
P value
<0.05
Statistical sugnificance
A study is said to be statistically significant when the p values is < 0.05. That is the chance that the difference between the groups compared is due to chance alone . The probability of any other reason is < 5 % .
Confidence interval
Gives a range between which the value fo rate true population will fall.
It helps determine the impact of the evidence in the population.
How does sample size affect CI
The CI narrows as the sample size increases.
Effect of variance on CI
Increase in variance widens the range of CI.
Qualitative research
Focuses on the social world and generation of theories.
Quantitative research
Science of numbers. Objective and structures. It measures things. Avoids bias. Theory testing
Descriptive studies
Concerned with person, place and time to answer questions like who, what, where and when.
May focus on the cause of something.
Change in something over time.
Eg: Case report. Mortality rate, Morbidity rate, Disease registers
Analytic studies
Main tool used for identifying the cause of the diasease and evaluating interventions.
0planned comparison between people with or without a disease, with or without exposure.
It focuses on WHY
Observational study
Observe why something is occurring. No intervention.
Experimental study
In the study you control / intervene and observe what happens.
Case report
Description of an individual patient
Case series
Report that combines multiple cases.
Cross sectional study is what type of study?
Analytical or descriptive
What type of question does cross sectional study answer?
Prevalence
Time frame fro cross sectional study
Single point in time
Results of cross sectional study
Exposure and outcome at a particular time.
Cohort study ?
Study a group of people over time. And compare them with another group.
Study the outcome.
Type of cohort study
Prospective
Retrospective
Case - control study
Look back to see which risk factors they have been exposed to.
Difference between cohort and case control study
Cohort - always start with exposure status
case control - start with outcome and then look at exposure.
RCTs
Experimental versus control group to learn the outcome of interest.
