Legal Issues in Surgery Flashcards
what are the two types of diathermy?
monopolar and bipolar
Advantages of bipolar?
heating is localised to the area between the two electrodes and surrounding tissue damage is minimised
Hazards of diathermy?
Patient burn
Explosion or fire
How to calculate relative risk?
relative risk = EER / CER
Event rate/control event rate
How to calculate positive predictive value?
Positive predictive value = TP / (TP + FP)
The chance that the patient has the condition if the diagnostic test is positive
How to calculate sensitivity?
TP / (TP + FN )
Proportion of patients with the condition who have a positive test result
How to calculate specificity?
TN / (TN + FP)
Proportion of patients without the condition who have a negative test result
How to calculate negative predictive value?
TN / (TN + FN)
The chance that the patient does not have the condition if the diagnostic test is negative
How to calculate likelihood ratio for a positive test result?
sensitivity / (1 - specificity)
How much the odds of the disease increase when a test is positive
How to calculate the likelihood ratio for a negative test result?
(1 - sensitivity) / specificity How much the odds of the disease decrease when a test is negative
what is the bolam test?
The Bolam test defines if a decision made by a doctor is in agreement with the professional standard of medical practise.
What is consent 1?
For competent adults who are able to consent for themselves where consciousness may be impaired (e.g. GA)
What is consent 2?
For an adult consenting on behalf of a child where consciousness is impaired
What is consent 3?
For an adult or child where consciousness is not impaired
What is consent 4?
For adults who lack capacity to provide informed consent
what components are needed to make a power calculation?
Size of effect
Significance level
Sample size used to detect the effect
Desired power value
What is a type 1 statistical error?
A test rejects a true null hypothesis. Analogus to false positive. It usually equates to the significance level assigned to a test.
what is a type 2 statistical error?
A test fails to reject a false null hypothesis. It is related to the power of a test.
What is statistical power?
Statistical power
The power of a test is the probability that the test will reject the null hypothesis when it is false (thereby avoiding a type 2 error)
Usually a value of 0.8 is selected.
What is pre-test probability?
The proportion of people with the target disorder in the population at risk at a specific time (point prevalence) or time interval (period prevalence)
What is post-test probability?
The proportion of patients with that particular test result who have the target disorder
Post-test probability = post test odds / (1 + post-test odds)
what are pre test odds?
The odds that the patient has the target disorder before the test is carried out
Pre-test odds = pre-test probability / (1 - pre-test probability)
What are post-test odds?
The odds that the patient has the target disorder after the test is carried out
Post-test odds = pre-test odds x likelihood ratio
where the likelihood ratio for a positive test result = sensitivity / (1 - specificity)
which test corrects against multiple statistical analyses that might provide an erroneous result?
Bonferroni method in which the observed p values are multiplied by the number of tests performed
