AAAA Therapy Flashcards
what is the AAAA framework?
Assess: what type of healthcare question –
what type of study?
Access: finding the ‘best’ evidence (validity
and relevance)
Appraise: evaluating the quality of the
evidence & interpreting the results
Act: is this evidence relevant to my clinical
practice. Should this evidence change my
practice?
why is the AAAA framework
important?
- An essential professional and academic skill
- Medical knowledge is continually evolving.
- The medical profession frequently fails to use
effective treatments even when they are
available. - Keeping up to date is a lifelong commitment for
every doctor. - You need to develop and use the skills to find,
appraise and act on research evidence.
explain the assess part of the AAAA framework
Assess: what type of healthcare question do you have - what type of study would best answer your question?
For this session we looking at effectiveness questions:
Will this therapy cause a beneficial effect in my patient?
Therefore, we will be using population based research (RCT) to answer the question:
how do you formulate an effectiveness question?
We formulate an effectiveness question by using a PICO framework:
Population
Intervention (treatment we are evaluating)
Comparator (alternative treatment/no treatment)
Outcomes (what are outcomes of interest) – benefits and harms
Formulating a PICO is important to:
To help with searching for evidence in electronic bibliographic databases such as MEDLINE
To help with assessment of applicability of population-based research to your patient population
how would you formulate a PICO question with this scenario:
A 45-year-old man consults you (his GP) for treatment for his chronic low back pain. You would normally refer him for a course of physiotherapy but the patient has requested a referral to a chiropractor. You want to know how effective chiropractic treatment is, compared to physiotherapy, for the treatment of low back pain before deciding where to refer him.
P –Adults; with chronic low back
pain
I - Chiropractic treatment
C –Physiotherapy
O - Pain at 3 months
- Ability to walk a mile
- Ability to work
- Harms from treatment
explain the access part of the AAAA framework
Access: finding the ‘best’ evidence
evidence that is most appropriate for your type of research question (RCTs)
evidence that is clinically relevant to your question
- Randomised control trials can be found:
Cochrane Library: https://www.cochranelibrary.com/central
Bibliographic databases like MEDLINE, PUBMED, EMBASE
MEDLINE and EMBASE have study design filters (including an RCT filter)
PUBMED has a clinical queries facility - Search Method
Use the components of your question (PICO) to make a search - usually terms for Intervention of interest and if necessary, to narrow search, the Population
Also if necessary restrict the search to RCT
Often more than one term is used to describe Population and Intervention components. These can be taken from:
bibliographic database thesaurus’ (MEdical Subject Headings)
Non MESH terms for the question component (free Text terms) – terms that you know are used to describe intervention of interest (use mixture to find most relevant terms.
Combine terms using Boolean operators:
“AND” gives search results which include both search terms
“OR” gives search results which include either one or other or both search terms
how is appraisal of the RCT design carried out
looking at how well RCT carried out, is it free from bias?
At its simplest, Appraisal asks:
Does the study address a research question which is relevant to my clinical problem?
(is there a match between my PICO & the study question?)
Did they use the study design most likely to provide a valid answer to the clinical question?
(for effectiveness question was it an RCT?)
Was the study done well / is the study trustworthy?
(were steps taken to reduce bias?) A poorly conducted RCT might be less valid that a well conducted cohort study.
If the study was done well (valid), what were the results?
(direction, size, precision and statistical significance of results)
were steps taken to reduce BIAS?
The targets below represent seven different measures of blood pressure from same person.
The true blood pressure is the centre of the target.
Which targets are biased?
Which targets are imprecise?
A + B are biased:
There is systematic deviation - not only are measurement deviated from the true BP, but deviations are all in the same direction i.e., pattern of deviation is systematically in one direction.
C + D are not biased:
Although measurements are not a true reflection of BP, the nature of deviation from the truth is more random
This is a random error.
No systematic pattern of deviation.
B + D are imprecise because measurements are scattered.
what is the method of a RCT?
A RCT is perspective: exposure (treatment) comes before the measuring of outcomes.
In a RCT individuals are allocated to receive either a new treatment or comparator treatment (existing treatment/no treatment)
The allocation to the two group occurs via randomisation
what are the key features of the RCT that needs to be included?
Comparator Group
Randomisation
Why have a control or comparator group?
If the comparator group was no treatment, it allows us to evaluate whether patients would get better without any treatment
Or if the comparator was another an existing treatment it, it allows us to see which treatment creates a better prognosis.
Why shouldn’t the drug manufacturer decide which patients are allocated to the new treatment or the comparator?
In any study the population will have a range of prognoses.
This is because individuals may have more/less severe form of the disease or the may have comorbidities.
Therefore, the ability of the tested treatment to benefit them will be different.
If we allow the manufacture to decide who receives new treatment and who gets existing treatment, there may be a tendency for people with a vested interest to make treatment look good to select people who have a better prognosis for their new drug and to allocate people who will receive competitor treatment into other arm.
You have an imbalance in patient characteristics of two arms that are being compared.
So regardless of how effective new treatment is, we would expect outcome to be different.
This is called selection bias
Why shouldn’t the patient’s Dr decide whether they want the new treatment or the comparator?
The Dr and their patient may feel that if they have more severe disease they have more to benefit from receiving a new treatment.
Therefore, again get an imbalance in the two arms so we have another selection bias.
We would expect outcomes to be different in two groups, irrespective to how effective new treatment it.
what needs to be done to ensure comparison of groups?
To ensure a valid comparison we want the groups to be similar on the outset of the trial.
This ensures any characteristics of participants that may affect the outcome will be equal across the groups compared.
This is done by randomisation.
Randomisation mitigates against section bias.
In a RCT of chiropractic treatment versus physiotherapy for chronic back pain, pain was measured after 3 months.
Which of the following measures is least likely to undermine the validity of RCT?
The most objective will be least prone to manipulation by those who are measuring outcomes or by patients.
This means it is least likely to undermine the validity of the RCT.
In an RCT of a new pain killer (intervention) compared to ibuprofen (comparator) for chronic back pain, some of the patients allocated to the new pain killer did not take this as directed but resorted to buying ibuprofen over the counter.
To uphold the validity of the RCT what should we do with the patients who did not take the new pain killer?
- Patients who did not take the new drug should be analysed with the group allocated the new drug (ignoring the fact they did not take the new drug)
- Patients who did not take the new drug should be excluded from analysis
- Patients who did not take the new drug should be analysed in the ibuprofen group (because they actually took ibuprofen instead)
Answer: Patients who did not take the new drug should be analysed with the group allocated the new drug (ignoring the fact they did not take the new drug)
Why? – This is called an intention to treat analysis
Patient characteristics associated with prognosis are often reasons why people “swap arms”.
People who have milder disease who have less to benefit from a new treatment but most to lose from side effects are most likely to not adhere.
If we exclude those participants, we get imbalance in arms of our trial and we undo randomisation.
If we preserved the swap, we also preserve an imbalance – we undo randomisation.
So, if we get people who swap arms, we analyse them as if they had not swapped.
This preserves randomisation.
In a randomised controlled trial to compare physiotherapy and chiropractic treatment in adults with chronic low back pain….
look at the table and predict what happened
53 adults were randomised to physiotherapy and after 3 months 33 were pain free.
In comparison 48 of the 57 adults randomly allocated to chiropractic treatment were pain free at 3 months.
Outcome: pain free – we want more of that
After we have our results, we should construct a 2x2 table of effectiveness.
Because the two groups of comparable size we can see chiropractic treatment is more effective than physiotherapy as a greater proportion of chiropractic group appear to be pain free after 3 months.
how do you measure effectiveness: (risk of benefit)?
The way we conceptualise effectiveness is by calculating risk of benefit.
Risk of benefit in chiro group (no pain after 3 months) is 48/57 = 84%.
Risk of benefit in physio group is 33/53 = 62%.
Therefore, it looks like chiropractic is more effective.
You can express this difference in effectiveness is by:
Calculating a risk difference:
Take the risk of benefit in the comparator group and take that away from the risk of benefit in intervention group.
So, we can express that difference as an increase in outcomes of 22% in our intervention group
Calculate a relative risk.
We divide risk of getting better in intervention group by risk of getting better in comparator group
0.84/0.62 = 1.35 🡪 35% higher risk of getting better in chiropractic group.
Number needed to treat:
Equation: 1/Risk difference.
The number needed to treat tells how many patients we need to treat with intervention for one more person to get better compared to comparator.
