Epi 1-3

Question 1

threats to validity

Answer 1

Bias

Confounding

Question 2

confounding aanpakken:
design:
analyse:

Answer 2

design: randomiseren, restrictie, matching
analyse: stratificatie, regression

Question 3

relatie tussen odds en proportions

Answer 3

small proportions geeft gelijke odds, hoge getallen zal grote verschillen geven: prop 0.5 = OR 1.0

Question 4

Prevalence =

Answer 4

proportie op 1 punt in tijd ziekte/totale populatie

s functie incidence & ziekte duration

Question 5

problemen met cum incidence

Answer 5

• competing risk
• loss to follow upv (problamtscih als non random lost to follow up).

oplossing: incidence rate (IR / T).

Question 6

MoA: RR, RD (attributable risk), OR

Answer 6

RR: R1/R0
RD = R1-R0
OR = (R1/1-R1)/[R0/1-R-]

Question 7

unieke eigenschap OR:

Answer 7

Symmetrisch/reciprocal: Odds NOT develop disease = 1/odds develop disease.

Niet waar voor andere MoA

Question 8

wat is meestal groter: RR of OR

Answer 8

OR

Question 9

Attributatble fraction

Answer 9

+1portion of risk AMONG EXPOSED that is attirbutatble to exposure. = AR%

AR% = (RR-1)/RR = RD/R1

among xposed, ..% of risk is attibutable to hypertension.

Question 10

Population attributable fraction

Answer 10

Tot AF: portiomn of risk in POPULATION that is attributable to exposure: PAR%

PAR% = [(p)(RR-1)][(p)(RR-1)+1].

p = prevalence of exposure = % exposed in population

Question 11

PAF% uitgeschreven in zin

Answer 11

..% of risk in this population is attributable to E.

Question 12

NNT

NNH

Answer 12

om 1 case te veroorzaken of voorkomen

NNT = 1/RD (als R1 < R0)
E verlaagt R

NNH = 1/RD (als R1 > R0)
(E verhoogt R)

Question 13

In geval van competing risks welke MoA kan je wel gebruiken en welke niet?

Answer 13

RR, OR niet

Rate ratio wel!

Question 14

Justification for RCT

Answer 14

equipoise: uncertainty about risk and benefits of treatment
meaning: sufficient expected benefit to gife treatment, sufficient doubt to withhold treatment from others

Question 15

Waarom is RCT goede benadering echte ffect?

Answer 15

geeft best mogelijke weergave van countferfactual (incidence controle groep).

Question 16

Oplossing dat er in kleine trials imbalance is:

Answer 16

random permutation (blocked randomization)

evt gecombineerd stratification: binnen stratum blocked randomization.

Question 17

Effictiveness =

efficacy =

Answer 17

expected effect of a treatment in actual practice

expected effect of a treatment in an ideal situation.

Question 18

Effect non compliance

Answer 18

observed effect of intervation towards 1.

Question 19

Doel blinding

Answer 19

Masks treatment assignment, to ensure that conduct of study post-randomization is fair

Question 20

hawthorne effect

Answer 20

subject acts differently when studied.

Question 21

primaire analyse RCT is altijd:

Answer 21

ITT

secundair kan wel compliers only (dit is dan non randomized want patietnen zelf selecteren).

Question 22

Pro cons factorial design

Answer 22

Can increase efficiency by studying multiple interventions in same populations, can examine whether effect of one treatment depends on another.

Cons: if there is interaction (effect modification) between treatments, decreased statistical power.

Question 23

Cluster randomized trials

Answer 23

randmonizeren per groep

limit: individuele chars niet evenredig verdeld,