Evidence Based dentistry Flashcards
abstract
- Condensed version of full paper
- Structured abstracts outline important elements
- Backgrounds/aim
- Methods
- Results
- Conclusion
- Good for screening but does not replace reading full paper
background/introduction
- What do we already know?
- What is not known?
- Justification/rationale
- Aims/objectives/hypotheses
Scan
Not important critical appraisal as not on methods or results
materials and methods
- KEY for critical analysis
- Used PICO to define the research question
- Sample size estimates
- Statistical analysis
- What tests and data manipulation
- Randomised controlled trial
- Randomisation method
- Allocation concealment
- Masking (blinding)
results
know aims, methods and controls already
Tables, charts and narratives
- Study characteristics
- Table 1 – what study population look like – should be similar on both side, can see if representative to your pts
- Outcomes
- Allows reader to judge how representative study sample is of target population
In RCTs – how balanced arms are
- Do results favour intervention?
- Is intervention better?
- Estimate effect size
- Risk difference
- Risk ratio (relative risk)
- Odds ratio
- Precision of estimate - CI
discussion, conclusion and references
- Context of study, given prior research
- Implication of these results on health condition involved
- Study limitations
- The likelihood that chance, bias and confounding have influenced the findings
- What else could have caused change
- The likelihood that chance, bias and confounding have influenced the findings
- References
acknowledgment and sources of funding
- Publication bias
- Trials more likely to be published if
- They produce positive results
- They reflect well on a product
- They are funded by industry
- Do authors have a financial conflict of interests
CONSORT flow chart
Describes flow of participants through study
See consort guidelines
Evidence Based Dentistry
- An approach to oral health care that requires the judicious integration of:
- Systematic assessments of clinically relevant scientific evidence, relating to the patient’s oral and medical conditions and history, together with Dentist’s clinical expertise and the patient’s treatment needs and preferences
ADA
critical appraisal
- The process of assessing and interpreting evidence through the systematic consideration of its validity, relevance and results
- What are the studies strengths and weaknesses and can it be used to inform your practice?
why critically appraise research papers
- To gain a full and in-depth understanding of a subject.
- To see if your intended research subject has been done before and avoid duplication.
- To avoid any errors made in similar research.
- To enable you to place your study within its context (ie so that you can show how your research will add to the existing sum of knowledge).
- To provide you with information with which to compare and contrast your findings.
- To provide you with ideas to help you define or amend your own research topic.
- To make sure that your ‘on the right track’ !
what decisons need to be made of evidence based dentistry
all clinical decisions
e.g
- Placing a stainless-steel crown Vs conventional restoration (GIC, composite)?
- Analgesia before treatment to reduce post-operative pain?
- Powered versus manual toothbrush?
- Recommending flossing to your patients?
- Is there any difference in effectiveness when undertaking root canal treatment in one visit compared to over several visits?
- What are the effects on pain and complications?
- What is the optimal interval for dental check-ups?
- 6 months – but what’s the evidence
- How effective are non-pharmacological interventions to manage orthodontic pain?
- Laser irradiation; laser devices; chewing patterns; brain-wave music; text messages
Does it differ for different pt groups? E.g. elderly Vs adult Vs child Vs special needs
RCT
Randomised Controlled Trials
- For research questions about effectiveness of one treatment compared to another RCTs are considered the gold standard study design (primary)
CASP Checklist
different tools for different types of studies
checklist for critical appraisal
3 main issues to consider when critically appraising
Are the results of the trial valid?
- Focussed question (PICO)
- Conduct of study (randomization, blinding, allocation concealment, flow of participants)
What are the results?
- Effect of treatment – what has been measured? what direction? How large?
- Precision - CIs
Are the results relevant to your clinical practice?
- Generalizable – people in trial reflect your pts
- Clinically important outcome measures
- Adverse effects/ harms?
did the trial address a clearly foccussed issue?
(making it valid)
SHOULD BE CLEAR AND SPECIFIC
- Population
- Intervention
- Comparison
- Outcome
PICO
Population
Intervention
Comparison
Outcome
how to assess if paper valid to you?
does the defined PICO match your patient population
how to assess if results valid
- Was the assignment of treatments to patients randomized?
- Were all of the patients who entered the trail accounted for at its conclusion?
- Were patients, health workers and study personnel “blind” to treatment?
- Were the groups similar at the start of the trial?
- Aside from the experimental intervention, were the groups treated equally?
CONSORT Flow
flow participants from randomisation to results
- Want to know that those that are initially randomised into the trial have the outcome measure
Occasional drop outs OK
Need to check systematic drop outs
- e.g. deaths – check not as consequence of intervention
- Were all of the patients who entered the trail accounted for at its conclusion?*
- affect validity*
importance of study personnel and HCP ebing ‘blind’ to treatment
- Not unknowingly placing bias/influencing results
- Less likely blinded more likely to get large effects on forrest plot
- Try to mask personnel as far as possible – can be hard – for more fair results
affect validity
how to check if radomised groups similar at start of trial
table 1
run down of characteristics of people at start of trial
Want to be balanced – should be done by randomisation but check
affect validitiy
bar the experimental intervention - were the groups equally treated?
affects validity
- If more than one intervention, then cannot deem it down to one thing*
- Everything else needs to be similar bar one*
e. g.
RCT for ankle bracelets for monitoring alcohol
- Intervention group
- “anklet”
- Counselling
- Control group
- TAU
F varnish to prevent caries
- Intervention
- Twice yearly application of FV at dentist
- Dentist will deliver dietary advice and OHI at each visit
- Control
- TAU (attend dentist as routine)
results - look at
difference between 2 groups results
e. g. absolute risk difference with CIs
* Need this 2:2 contingency table to get this information*
Absolute risk difference
- Difference in risk between groups
Risk in paracetamol group= 40/63= 63%
Risk in placebo group=5/27= 18%
Risk Difference = 63% - 18% = 45%
- 45% more patients experienced pain relief in the paracetamol group
*
confidence intervals
The range of values the ARD will take in the population
- 95 times out of 100 the CI will contain the TRUE population ARD
What value would ARD take if there was no benefit of paracetamol over placebo?
- 0 (value of no difference)
- So 95% CI should not overlap “0”
ARD= 45%
- 95% CI= [30% to 55%] never have to calculate this – should be given
- “Sufficient evidence”
value of no difference
0
CI cannot overlap 0 = insufficient evidence
number needed to treat
NNT
The number of patients you would need to treat to prevent one patient from developing the disease/ condition/ outcome
- Numerically:
- 1/ Absolute Risk Difference
NNT for paracetamol = 1/ 0.45 = 2.22
- Would need to treat 3 people with paracetamol post-operatively to have one person experience pain relief of >50% in 4 hours
- Compare to NNT for statins ~ 33 (paracetamol has a good NNT)
advantages of split mouth design
- Each participant acts as own control-reduces inter-individual variation
- Therefore, fewer participants are required to obtain same study power as parallel group
- Every participant receives each intervention, therefore good for determining preferences
- Experience both
split mouth design
Control treatment and intervention in the same mouth
- Caries in both sides of arch – randomise the side of mouth getting intervention compared to TAU
e. g. Lower arch with Hall PMC on tooth 85 (LRE) and Control restoration (mesio-occlusal composite) in tooth 75 (LLE).
possible disadvantages of split mouth design
- Carry-across effects (“leakage”)
- E.g. toothpastes, mouthwashes
- Selection of patients (need to have matching carious teeth) might limit external validity
- May not have appropriate carious sites
- Statistical analysis more sophisticated, and is usually not done!
Own control and intervention – can be missed in analysis
what happens when some study participants drop out before the end of trial or switch treatment?
Eg RCT for a tooth bleaching agent
- Participants randomized to NEW agent or Current market leader
- A few participants who were randomized to the NEW agent do not like the bad taste and go to their own dentist and ask for the current market leader
- Switched but didn’t inform you at point
- Can occur by mistake – need ways to analyse
- A few participants who were randomized to the NEW agent do not like the bad taste and go to their own dentist and ask for the current market leader
Intention to treat (ITT) should be clear how many people have switched treatments
- Analyse the data as though the switchers were still in the NEW agent group
- More conservative (PREFERRED)
- Pragmatic- in real life this will happen
- Drop outs
- Can impute data
- (LOCF/ BOCF)
Per Protocol
- Analyse the data according to the treatment actually received
- Efficacy to explain the effects of the intervention itself
stats that can be used in results
- Absolute risk differences
- CIs (+/- 95%)
- Odds ratio (OR)
- Relative risk, or risk ratio (RR)
- Percent risk reduction, or relative risk reduction (RRR)
- Risk difference, or absolute risk reduction (RD)
- Number needed to treat (NNT) (1/RD)
preferred method to use is participants drop out or switch Tx
Intention to treat (ITT) should be clear how many people have switched treatments
- Analyse the data as though the switchers were still in the NEW agent group
- More conservative (PREFERRED)
- Pragmatic- in real life this will happen
- Drop outs
- Can impute data
- (LOCF/ BOCF)
