Correct Information in Gynaecology
Evidence based and authority based expert opinion are complementary
Evidence based medicine (EBM) is less than 10%
- The double blind randomized controlled trial (RCT) is mathematically correct. If technically well performed it will exclude inclusion bias (randomised controlled) , exclude placebo effect or woman bias (blinded) , and observer bias (double blinded).
- The value of all other studies, as cohort or others studies needs a close evaluation of material and methods and ranges from excellent to poor.
- What is proven should not be discussed unless there is a technical problem in design or in blinding
- What is not clear is ‘not proven’, but should not be dismissed as ‘not true’
- The RCT
- is tedious
- is slow in adding information
- Is not suited for rare events; eg a complication occurring in 1% of surgery needs a RCT of 6000 women in order to have 30 cases in the control group and 30 in the test group. This is rarely realistic.
- The more strict inclusion criteria are, the more difficult ithe extrapolation of results becomes
- A RCT therefore is not suited for multimorbidity, eg the patient with deep endometriosis, AND diabetes AND hypertension AND …….
- A RCT balances between evidence which is already so likely that it is close to unethical to perform the trial and a difference which is so little that the result is clinically not important
- RCT are of limited value when blinding is impossible eg for medical treatment of endometriosis
Authority based expert opinion
- More than 90% of medicine is experience based expert opinion, which integrates what has been demonstrated with the characteristics of the individual patient ie age, weight other diseases etc.
- Experience and rules are often introduced following (near) accidents seen in the past e;g; explosion risk with pure N2O during laparoscopy.
- These authority based rules which are a consensus opinion of experts are undervalued and should be upgraded in the pyramid of evidence
Clinical decision making
For diagnosis= diagnostic accuracy of a test
- consider sensitivity and specificity and the many pittfalls as
- the low predictive value which is low when prevalence is low
- precision of the test
- what does the test evaluate ? especially important for imaging in endometriosis
- Treatment balances the expected benefits with the risks of treatment
- Freedom of treatment is limited to what is accepted at a certain point in time
- a new type of surgery should be performed as a trial with close evaluation
- treatment contract should be explained in informed consent
Therefore who gives information is important
- Check publications
- check presentation
Do not trust personal opinions
Prof P.R. Koninckx
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