Study Designs, Advantages, Disadvantages

Front 1

What are the major advantages of cross sectional studies?

Back 1

1. Low Cost, Efficient
2. Generalizability of the results.
3. Generates a hypothesis for further research

Front 2

What are the major disadvantages of cross sectional studies?

Back 2

1. Temporal relationship problems
2. Prevalence Bias (how long did people have the disease)
3. Selection Bias
4. Confounding.
5. Difficult to study rare diseases/exposures

Front 3

What are the major advantages to cohort studies?

Back 3

1. Time sequence. Exposure preceeds disease/event.
2. Ethical to study since exposure is not being created.
3. Can eliminate some information bias since disease/event has not occured
4. Less prone to selection bias since outcome has not occured yet.
5. incidence rates can be measured
6.Multiple outcomes can be investigated for a single exposure

Front 4

what are the major disadvantages to cohort studies?

Back 4

1. cost. fairly expensive.
2. Difficult to study rare disease outcomes
3.. Validity: Confounding, information bias, Lost to follow up
4. Non participation.Only a portion of population eligible will enroll iln study. May not represent true population.

Front 5

What are the major advantages of case control studies?

Back 5

1. Rare diseases can be studies easier.
2. Efficiency and Cost
3. Multiple exposures can be studied
4. The OR is a good estimate of the RR.

Front 6

What are the major disadvantages of case control studies?

Back 6

1. Information Bias
2. selection bias
3. Prevalence bias
4. Confounding
5. Temporal relationship problems

Front 7

What are the major advantages of intervention studies?

Back 7

1. Only study design that can 'prove' causality
2. You can calculate the IR
3. Temporal relationship problem is resolved.
4. Selection bias is ruled out
5. Multiple Outcomes can be studied for a single exposure

Front 8

What are the major disadvantages of intervention studies?

Back 8

1. Exposure is being applied, only preventative programs can be tested through intervention studies. Can not expose people to diseases.
2. Cost; fairly expensive
3. Validity: Placebo effect, info bias, loss to follow up , confounding

Front 9

What are the major advantages of case report/case series studies?

Back 9

1. Cost, Efficient
2. Early warning.
3. Can serve as a basis for creating a hypothesis

Front 10

What are the major disadvantages of case report/case series studies?

Back 10

1. Cannot test any hypothesis ( no compare/control group)
2. Generalizability may be limited. (case reports may be exceptions from the population)

Front 11

What are the major advantages of ecological studies?

Back 11

1. Efficient. (Can be done quickly)
2. Population based measures of outcome
3. Preliminary testing of hypothesis. (serves as a basis for analytic study)

Front 12

What are the major disadvantages of ecological studies?

Back 12

1. Cannot control for many confounding variables.
2.Ecological Fallacy (no garantee that the persons with the disease are the same ones with the exposure)

Front 13

What are the advantages of a historical clinical trial?

Back 13

1. Less people required for the study
2. can be carried out when randomization is not feasible

Front 14

What are the disadvantages of a historical clinical trial?

Back 14

1. Control group may not be comparable. ( so many factors have changed)
2. Lack of uniform inclusion criteria
for control
3. Inferior data quality in control group
4. Differences in evaluatory methods

Front 15

What are the advantages of a factorial design study?

Back 15

1. Two or more treatments can be compared in a single trial using the same number of patients needed to test one treatment

Front 16

What are the disadvantages of a factorial design study?

Back 16

1. Not always possible to give patients combinations of medicine
2. There can be no interaction of the med's

Front 17

What are the advantages of a crossover study?

Back 17

1. Within patient comparisons allow for more precision and smaller sample sizes (patient serves as their own control = Perfect matching)
2.

Front 18

What are the disadvantages of a crossover study?

Back 18

1. Not suitable for unstable diseases
2. cannot be used if there is a carry over effect from one treatment
3. Can not be surgical procedures or long term drug therapy

Front 19

Simultaneous Non-randomized Clinical Trials. Advantages:?

Back 19

1. Study groups are samples of convenience.
2. Eliminates the problem with non-comparibility of data collection ( as seen in historial control trials)

Front 20

Simultaneous Non-randomized Clinical Trials. DisAdvantages:?

Back 20

1. Non comparability of groups remains a disadvantage. In fact maybe even more so than historical controltrials because assignment to groups is not taken at random.

Front 21

Randomized Clinical Trials. Advantages:

Back 21

Randomization will achieve comparability among treatment groups.

Front 22

Why is iodine important to have in the diet?

Back 22

Iodine is needed by the thyroid gland to produce thyroxine (T4). Each T4 has four iodine atoms. In areas of the world where iodine is lacking, the thyroid gland is swollen (goiter)

Front 23

Why the lack of iodine in the diet cause swelling of thyroid gland?

Back 23

lack of dietary iodine to make them, gives rise to high levels of thyroid stimulating hormone TSH, which stimulates the thyroid gland to increase many biochemical processes; the cellular growth and proliferation can result in th characteristic swelling or hyperplasia of the thyroid gland, or goitre

Front 24

Iodine deficiency can lead to:

Back 24

Mental Retardation and other health issues