Johns hopkins Course Module 6

Question 1

How to put hyerarchy of a evidence?

Answer 1

At a very bottom to the top:
Unsystematic clinical observations
Pshysiologic studies
Single observational studies adressing patient-important outcomes
Systematic review of observational studies adressing patient-important outcomes
Single randomized trial
Sistematic review of RCTs

Question 2

what can lover the level of evidence of trials?

Answer 2

1, risk of bias

2. Inconsistency
3. Indirectiness
4. Imprecision (confidence interval)
5. Publication bias

Question 3

Key strenghts of RCTs?

Answer 3

Randomization:
unbiased assignment of treatment
link between prognosis and precriscption is broken
comparable groups on known and unknown factors
application of statistical methods based on random sampling

Standardization:
treatments
outcomes assesments

Question 4

Why there are different results of observational and clinical studies (VItamin C)?
only one

Answer 4

residual confounding- social and enviromental exposures across life

Question 5

Resdiual confundingl 4000 women?

Answer 5

o they took these 4,000 women and broken them up into four groups based on their serum level of vitamin C.

1. Socioeconimc factors
2. behavioural and lifestyle risk factors
3. biomarkers childhood environment

Everyone of these indicators was individually associated. So if you adjusted for the other ones you still saw this effect

Question 6

What are Lawler findings?

Answer 6

SES factors have strong linear effect

independent effect: adult behavioural factors independently assoiciated; child development factors also

Question 7

What are life course cofounders consideration?

Answer 7

dont assume dependance
may not be linear
there may be interaction

Question 8

Conclusions of difference between Nurse and WHI studies on HRT?

Answer 8

Ascertaintment bias combined with misclasification and selction bias (residual confounding) can explain the difference
Ascertaintment bias affects outcomes for which there is belief about effect (CHD, not stroke)
Patience expectations influence outcome
all studies should include: Masked evaluation of outcomes: objectivly defined outcomes

Question 9

what is survival bias?

Answer 9

different use of treatment by study type:
observational -users vs nonusers
RCTs- intiators vs noninitiators