Epidemiology Lecture 6 Randomized Trials

Front 1

What is the purpose of randomized trials?

Back 1

To evaluate the effectiveness and side effects of new and established interventions for disease prevention and therapy

Front 2

What are the 3 essential features of effective studies?

Back 2

1) controlled
2) randomized
-patients assigned at random to assigned groups
3) Blind, ideally double blind

Front 3

What does it mean if a study is controlled?

Back 3

Compare a treated group to a control group who did NOT receive the treatment

Front 4

What do we mean by a blind or ideally a double- blind study?

Back 4

Patient and ideally the observer, don't know who is in the treatment group and who is in the control group

Front 5

What is the basic design of a randomized trial?

Back 5

Defined population -----> randomized-----> new treatment + current treatment
-New treatment---> improved + not improved
-Current treatment----> improved + not improved

Front 6

Why should the study population should be defined in writing?

Back 6

because this is the population you can make inference to in terms of your experimental results

Front 7

What are the 2 steps to selection of subjects & allocation to treatment group?

Back 7

1) Defining the study population in writing
2) Randomization

Front 8

What are 2 methods used to randomize a population when performing randomized trials?

Back 8

1) Flip a coin
2) Use a random number table

Front 9

When should the assignment of to control groups and experimental groups be made?

Back 9

Before seeing the patients or by an outside party (NOT the investigator)
---> assignment of the next patient unpredictable to patient and investigator

Front 10

What are 2 things that must be considered when examining a control group compared to an experimental group?

Back 10

Have to consider division by sex and age- were things randomized or is one group more old vs young patients?

Front 11

What is the definition of internal validity?

Back 11

Extent to which study results are corrected for sample of patients being studied

Front 12

What are 3 factors that affect the internal validity of a study?

Back 12

1) Randomized
2) Controlled
3) Blind

Front 13

What is the definition of external validity?

Back 13

Generalizability, the extent to which results of a study can be generalized to the whole population

Front 14

What question do you need to ask yourself when considering the external validity of a study?

Back 14

Is the sample of patients in the study REPRESENTATIVE of the patient population as a whole???

Front 15

What are 7 validity questions you need to ask yourself when examining a study?

Back 15

1) Is the case definition explicitly, exclusive and uniform?
2) Is a comparison group explicitly identified?
3) Are both treated and control patients selected from the same time and place?
4) Are patients allocated to treatment and control groups w/o bias?
5) Is the intended intervention, and only that intervention, experienced by all of the patients in the treated group and not in the control group?
6) Is the outcome assessed without regard to treatment status
7) Is the method used to determine the significance of the observed results defined explicitly? Can we be certain that the observed results could not have occurred by chance alone?

Front 16

What is the best approach for evaluating the effectiveness and side effects of disease and interventions?

Back 16

Randomized trials

Front 17

What are the 3 things that are essential to ensuring internal validity of a trial?

Back 17

1) Randomization
2) Controls
2) Blinding

Front 18

What does the external validity of a study depend on?

Back 18

The study population being representative of the total population of interest

Front 19

What is the only way to get conclusive answers?

Back 19

Performing Experiments