Term
| Steps for Conducting Biomedical Studies |
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Definition
Assignment
Assessment
Analysis
Interpretation
Extrapolation |
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Term
| Cross-Sectional Design Strengths |
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Definition
Rapid results
Low cost
Little loss to follow-up
Used for prevalence studies |
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Term
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Definition
| start at single point int time, determines who has the disease at that point and time, ask them to recall risk factors they have had in the past |
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Term
| Cross-Sectional Design Weaknesses |
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Definition
bias from recall or volunteer
temporal relationship |
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Term
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Definition
| identify a group of cases, find a similar group of controls, ask them to recall their exposure in the past |
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Term
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Definition
Rapid results
Low cost
Little loss to follow-up
Used for rare diseases |
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Term
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Definition
bais
temporal relationship |
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Term
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Definition
Exposure precedes disease
Relative risk can be directly assessed
Exposure monitored prospectively |
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Term
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Definition
time
expense
loss to follow up |
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Term
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Definition
prospective sutdy design even if it is a retrospective cohort design
strt with a study population and they are free of disease at the start of the design, follow them in time and record when you get the disease at some point in time |
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Term
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Definition
investigator decides who gets the exposures
start with study population that is disease free or have a disease, then apply a treatment/control and follow them in time and see who develops disease in the future |
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Term
| Controlled Experiment Strengths |
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Definition
Exposure carefully controlled and monitored
Used for clinical trials |
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Term
| Controlled Experiment Weaknesses |
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Definition
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Term
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Definition
| the subset of the general populations defined by eligibility criteria |
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Term
| Randomized Control Studies |
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Definition
The standard against which other designs must be compared
All subjects are equally likely to be assigned to the intervention or control |
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Term
| Randomized Control Studies Advantages |
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Definition
Removes the potential of bias is the allocation of subjects to the intervention group or control group
Randomization tends to produce comparable groups
Validity of statistical tests of significance is achieved |
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Term
| Randomized Control Studies Disadvantages |
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Definition
| Ethical and Emotional Reasons |
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Term
| Non-Randomized Concurrent Control Studies |
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Definition
| Controls are subjects treated without the new intervention at approximately the same time as the intervention group is treated |
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Term
| Non-Randomized Concurrent Control Studies Advantages |
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Definition
| Eliminates the need for investigators to convince potential study participants of the need for randomization |
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Term
| Non-Randomized Concurrent Control Studies Disadvantages |
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Definition
| Intervention group and control group are not strictly comparable |
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Term
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Definition
A new intervention is used in a series of subjects; results are compared to the outcome in a previous series of comparable subjects
The design is non-randomized and non-concurrent |
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Term
| Historical Controls Advantages |
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Definition
New subjects all receive the new intervention
Ethically sound
Time to get the required number of subjects will be shorter |
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Term
| Historical Controls Disadvantages |
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Definition
Vulnerable to bias
Claimed success may be due to factors other than intervention
Diagnostic criteria
Change in patient management
Change in patient population
Difficult to establish the accuracy and completeness with which control group data were collected |
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Term
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Definition
This is a special form of a randomized control trial that has appeal to biomedical researchers
The COD allows each patient to serve as his/her own control
In a typical two period cross-over design, each patient will receive either intervention or control (A or B) in the first period and the alternative in the succeeding period
The order in which A or B are given to the patient is randomized
Approximately half of the patients receive the intervention in the sequence AB and the other half in BA |
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Term
| Cross-Over Design Advantages` |
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Definition
The COD allows assessment of whether each patient does better on A or B
Since each patient is used twice, variability is reduced because the measured effect of the intervention is the difference in an individual subject’s response to intervention and control |
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Term
| Cross-Over Design Disadvantages |
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Definition
May have problems with effects of carry-over of the first intervention into the second period
Statistical tests for testing the assumption of no period-treatment interaction are not well developed in terms of power |
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Term
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Definition
Patients are taken off the intervention or have the dose reduced; the objective is to assess the response to discontinuation or reduction
May be validly used to evaluate the duration of benefit of an intervention which is already known to be useful |
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Term
| Withdrawal Studies Advantages |
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Definition
| Useful in assessing the efficacy of an intervention that has never conclusively been shown to be beneficial |
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Term
| Withdrawal Studies Disadvantages |
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Definition
| Only those patients that clinicians think will benefit will be used, this leads to overestimating the benefit and in some cases underestimating the toxicity |
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Term
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Definition
| attempts to evaluate two interventions compared to control in a single experiment |
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Term
| Factorial Design Advantages |
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Definition
very useful where we need to measure interactions of two drugs
actually two interventions are compared at once |
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Term
| Factorial Design Disadvantages |
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Definition
existence of interaction and its impact on the sample size
the effect of intervention X differs depending upon the presence or absence of intervention Y or vice versa |
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Term
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Definition
Also called composite randomization design
A clinic or community are randomized to a particular intervention or control |
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Term
| Group Allocation Design Advantages |
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Definition
| Has been used where there was difficulty in approaching subjects about the idea of randomization |
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Term
| Group Allocation Design Disadvantages |
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Definition
| Unit of comparison is not the individual patient, but groups |
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Term
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Definition
combine two types of designs
not efficient difficult to conduct and analyze |
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