Epidemiolgy 7-Assesing preventive and Therapeutic measures, randomized trials

Question 1

Why is randomized trials so important ?.

what are two settinng for randomized trails ?

Answer 1

Randomized trials

• Ideal design for evaluating the effectiveness and the side effects of new forms of intervention.
• Clinical setting and community-based trial

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Question 2

Ramdomized trials has many purposes, what are those ?

Answer 2

Randomized trials

•Many purposes

–Evaluating new drugs and other treatments of disease

–Tests of new health and medical care technology

–New programs for screening and early detection

–New ways of organizing and delivering health services

Question 3

.What does randomized trials help us do ?

Answer 3

Randomized trials

• Study population that is randomized to receive the new treatment or current treatment
• Follow up the study population
• To compare the subjects in each group to see how many are improved in the new treatment with the current treatment group.

Question 4

What must be done after the participants are chosen ?

Answer 4

Selection of subjects

•The criteria for determining who will or will not be included in the study must be spelled out with great precision and in writing.

Question 5

What do case study and case series have in common ?

Answer 5

Studies without comparison

•Case study or case series

–No comparison is made with an untreated group or with a group that is receiving some other treatment

Also very descriptive!!!

Question 6

.What purpose does historical control serve ? Where is the information being obtained ?

Answer 6

Historical controls

• We could use a comparison group from the past
• We have a therapy today that we believe will be quite effective and we would like to test it in a group of patients
• For comparison we will go back to the records of patients with the same disease who were treated before the new therapy became available

Question 7

.What is the problem of doing a historical control right now on a current new current population ?

Answer 7

Historical controls

•Problems

–If today we decide to carry out the study we may set up a very meticulous system for data collection from the patients currently being treated

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Question 8

What are some problems with Historical controls, with patient information ?

Answer 8

We cannot do that for the patients who were treated in the past for whom we must abstract data from medical records

–Records were generated for clinical purposes at the time and not for research purposes

Question 9

What is a problem of using historial controls when comparing to a new study findings ?

Answer 9

Question 10

What are problems that arise from comparing historial controls to current studies that were done.

Answer 10

Question 11

When is historial control useful in knowing a certain drug is effective ?.

Answer 11

Question 12

What is an example of simultaneous nonrandomized control using birthday ?

Answer 12

Simultaneous nonrandomized controls

Possible approaches for selecting nonrandomized controls

–Assign patients by the day of the month on which the patient is admitted to the hospital

• Odd numbers -Group A
• Even numbers-Group B
• Selection bias

Question 13

What is a simple and ramdomized way to determine which group gets the drug and the other placebo?

Answer 13

Randomized trials

•Randomization

–Best approach in this design

–Tossing a coin to decide the assignment of a patient to a study group

–Unpredictability of the next assignment

Question 14

What are key points an investigar needs to be insure his randomized group has ?

Answer 14

Diveristy

Using a statistical program

–No subjective biases of the investigator

–Increase the likelihood that the groups will be comparable in regard to characteristics

•sex, age, race, severity disease .

Question 15

What is an example of stratified randomization? What is the purpose of this ?

Answer 15

Stratify by gender and age

•Four groups

–Young females

–Old females

–Young males

–Old males

•Randomization of all participants to treatment groups

–Increase the comparability in terms of sex and age

Question 16

What is called when the participant does not know which group he is in ? Why is this important ?

Answer 16

Masking (Blinding)

•We would like the subjects not to know which group they are assigned to

–If the patient knows that he or she receives a new treatment, enthusiasm and certain psychological factors may operate to elicit an improved response

Question 17

What is the purpose of a placebo during when masking a participant ? How does the placebo compare to the real drug ? What is double blinding ?

Answer 17

Masking (Blinding)

• We could use a placebo (inert substance)
• Placebo (looks, tastes and smells like the active agent)
• We also want to mask the observers or data collectors in regard to which group a patient is in.

–Double blinding

Question 18

What is a planned cross over ?

Answer 18

Crossover

•A planned crossover

–New treatment is being compared with current treatment

–Subjects are randomized

–Follow up and measures

–Patients are switched to the other therapy

–Follow up and measures

Question 19

During a crossover, what is vital during a residual treatment ? When is a crossover design not possible ?

Answer 19

Crossover

•Problems

–Residual treatment

•We need a time period

–A crossover design is not possible if the new therapy is surgical or if the new therapy cures the disease

Question 20

What is unplanned crossover ? What kind of consent is given using randomization ? Example using surgery and medical treatment

Answer 20

Unplanned crossover

• Randomization is carried out after informed consent has been obtained
• Some subjects assigned by randomization to bypass surgery or medical treatment only

–Subjects may begin to have seconds thoughts and decide not to have the surgery. They are therefore crossovers into the medical care group or vice versa

Question 21

What is factorial design ?.

Answer 21

When there multiple indepedent variable for the outcome .

X+Y+Z=#

Factorial design

•Assuming that the 2 groups are to be tested the anticipated outcomes for the 2 drugs are different and their modes of action are independent one can economically use the same study population for testing both drugs.

Gordis,