Lec 4 Flashcards
what is the aim of a research study for an optometrist
to underpin understanding of clinical and health research methods relevant to the practising optometrist
what are the 2 types of EBM
- primary research
- secondary research
what is primary research
- it is written by the researchers themselves
- usually in journals or articles
- it is the outcome of a single study
- peer reviewed
what is secondary research
- summarises findings of multiple trials, experiments or surveys on the same topic
(answering a research question by looking at research papers produced by others)
what is the aim of a experiment in clinical research
proving or contradicting a hypothesis with data
what is a experiment in clinical research interested in
interested in an outcome (dependent) which may be influenced by an attribute (independent)
in the form of an EBM
e.g. does smoking cause AMD
name the 2 primary research study types
- observational studies
- experimental studies (clinical trials)
which are 2 different ways of answering a hypothesis
how does an observational study work
the investigator has no control over exposures to risk or treatments and instead observes what happens to groups of people
how does a experimental study (clinical trial) work
conditions are under the direct control of the investigator
e.g. select a sample of people and follow up with them and a control group in X amount of years and then notice a pattern
which type of primary research study type provides the best evidence for clinical research and why
experimental studies (clinical trials)
as it is the best way to prove something, we do something/there is an intervention
what are the 3 forms of study in observational studies and when does each occur
- retrospective study - in the past
- present time
- prospective study - in the future
name the 4 types of observational studies and what differentiates them
- case reports
- case-control study
- cross-sectional study
- cohort study
the time when the studies were done
which 2 types of study is a retrospective study (done in the past)
- case reports
- case-control study
information and data were done in the past
which type of study is carried out at present and give an example
cross sectional study e.g. a survey
which type of study is a prospective study (done in the future)
cohort study
which type of retrospective study is typically done on one person
case report
give an example of how a case report is carried out
- look through patient records
- e.g. select a patient with AMD
- assess whether they are smokers
name the advantages of a case report
quick, simple and cheap
name the disadvantage of a case report
no control group - px may have developed AMD anyway, so not sure if its to to with the attribute your looking at or to do with the person itself
which type of retrospective study is considered to be at the bottom of the hierarchy of EBM and why
case reports
it is a type of anecdotal evidence and carries the least weight
what can a case report lead to
bigger sorts of questions
what is the next best type of retrospective study to do if you dont have a case report
case-control study
what is the difference between a case report and a case-control type of retrospective study
case-control type has control group
list the advantages of a case control study
- relatively easy to do
- provides a measure of risk of smoking beyond chance (compared to what it would be if your won’t a smoker)
what can be difficult with a case-control study
selecting the ‘matched’ control group
e.g. it is difficult to make sure your control group are exactly the same as the patient with the AMD, but only difference is they haven’t got AMD = hard to match the group
list 3 disadvantages of a case-control study
- recall bias
- inaccuracy of retrospective data
- detection bias
how is recall bias a disadvantage of a case-control study
it is interviewing and selectively recalling past event - it is done by other people, so may not have real truth in it especially if it is remembered and not recorded as this can be forgotten
what is an example of inaccuracy of retrospective data, as a disadvantage of a case-control study
incomplete hospital notes
so your relying on other people to collect the data and not done yourself so the information may not be collected properly
explain how detection bias is a disadvantage of a case-control study
exposure related to risk of detection e.g. diabetes or obesity
the way we collect our data is important as well
how are cross-sectional studies carried out
done via a survey or questionnaire, done in one snapshot at a time/at present
what is another work for prospective observational studies
longitudinal studies
what is the idea of a prospective/cohort study
to identify a study group and follow them in the future
what is the advantages of a prospective/cohort study
- better data and extra information
- no recall bias and people entering the data incorrectly
list the 3 disadvantages of a prospective/cohort study
- long and expensive
- loss to follow up (subjects change habits, move or die)
- surveillance bias (at risk group is monitored too closely) e.g. done too carefully which is how you wouldn’t normally do it in real life
what arises in all observational studies
confounding
what is a confounder
a 3rd variable which explains or masks the observational effect
how can you figure out the confounders
it is to match the people your looking at with controls
how can you avoid confounding
by careful matching
what is the confounder in ‘number of limb fractures is lower in student nurses than in the age-matched university population of the same size’
gender
what is the confounder in ‘several published observational studies have indicated a high rate of lung cancer in professional chefs’
gender, smokers, stress
what is the confounder in ‘a published study indicates that myopia development in children is affected by ambient light in the bedroom’
genetic/parents
list the hierarchy of observational studies from highest to lowest rank
- cohort studies
- case-control studies
- cross-sectional studies
- case reports
