Prep ACVPM – Comprehensive Study Guide and Practice
Material
2 Clinical Study Types - ANS✔✔ Experimental vs Observational
Which clinical trial is the strongest evidence of the clinical efficacy of preventative and
therapeutic procedures - ANS✔✔ Randomized Controlled Clinical Trial
Prospective, analytical study
Indviduals simalr at the beginning are randomly allocated to 2 or more tx groups
Outcomes of groups are compared
Describe Randomized Cross over clinical Trial - ANS✔✔ Indviduals with a chronic condition are
randomly allocated to one of 2 tx groups then switched to the other for the same period
Carry over effects from 1st tx can occur
Symmetry Principle - ANS✔✔ Keep all things between groups similar except for the treatment
of interest
Screening Bias - ANS✔✔ Find the disease sooner but the course of the dz can not be changed
by clinical intervention thus it makes the survival time seem longer because you found it earlier
Non differential bias - ANS✔✔ Opportunities for bias are equivalent in all study groups, biases
the outcome measure of the study toward the null of no dfference between the groups
Differential bias - ANS✔✔ opportunities for bias are different in different study groups, biases
the outcome measure of the study in unknown ways (case control studies are highly susceptible
Matching - ANS✔✔ A way to control confounding
, Individual cases are matched with individual controsl with similar confounding factors to reduce
the effect of confounding factors on the association (most often seen in case control studies)
Restriction (specification) - ANS✔✔ Eligibility for entry into a study is restricted to individuals
within a certain range of values fo ra confounding factor (limits the external validity)
Census - ANS✔✔ A sample tha tincludes every individual in a population or group
Systematic sampling - ANS✔✔ example every 4th animal
Cluster sampling - ANS✔✔ staged sampling like select a kennel or stable and sample all
indviduals within the cluster
How do we get the odds ratio cross equation (ad/bc) - ANS✔✔ Odds that an exposed person
develops a disease (a/b) divided by odds that a non-exposed person develops the disease c/d is
equivalent to ad/bc
In a matched case control study... - ANS✔✔ one or more controls are selected to match to a
case on certain characteristics (age, crace, gender) this then forms a MATCHED PAIR
Concordant pairs - ANS✔✔ Either case and control were both exposed or both were not
exposed
Discordant pairs - ANS✔✔ Either the case was exposed and the control wasn't or the other way
around
When you calculate a matched odds ratio you only care about - ANS✔✔ discordant pairs!! (so
section B and C of your
Material
2 Clinical Study Types - ANS✔✔ Experimental vs Observational
Which clinical trial is the strongest evidence of the clinical efficacy of preventative and
therapeutic procedures - ANS✔✔ Randomized Controlled Clinical Trial
Prospective, analytical study
Indviduals simalr at the beginning are randomly allocated to 2 or more tx groups
Outcomes of groups are compared
Describe Randomized Cross over clinical Trial - ANS✔✔ Indviduals with a chronic condition are
randomly allocated to one of 2 tx groups then switched to the other for the same period
Carry over effects from 1st tx can occur
Symmetry Principle - ANS✔✔ Keep all things between groups similar except for the treatment
of interest
Screening Bias - ANS✔✔ Find the disease sooner but the course of the dz can not be changed
by clinical intervention thus it makes the survival time seem longer because you found it earlier
Non differential bias - ANS✔✔ Opportunities for bias are equivalent in all study groups, biases
the outcome measure of the study toward the null of no dfference between the groups
Differential bias - ANS✔✔ opportunities for bias are different in different study groups, biases
the outcome measure of the study in unknown ways (case control studies are highly susceptible
Matching - ANS✔✔ A way to control confounding
, Individual cases are matched with individual controsl with similar confounding factors to reduce
the effect of confounding factors on the association (most often seen in case control studies)
Restriction (specification) - ANS✔✔ Eligibility for entry into a study is restricted to individuals
within a certain range of values fo ra confounding factor (limits the external validity)
Census - ANS✔✔ A sample tha tincludes every individual in a population or group
Systematic sampling - ANS✔✔ example every 4th animal
Cluster sampling - ANS✔✔ staged sampling like select a kennel or stable and sample all
indviduals within the cluster
How do we get the odds ratio cross equation (ad/bc) - ANS✔✔ Odds that an exposed person
develops a disease (a/b) divided by odds that a non-exposed person develops the disease c/d is
equivalent to ad/bc
In a matched case control study... - ANS✔✔ one or more controls are selected to match to a
case on certain characteristics (age, crace, gender) this then forms a MATCHED PAIR
Concordant pairs - ANS✔✔ Either case and control were both exposed or both were not
exposed
Discordant pairs - ANS✔✔ Either the case was exposed and the control wasn't or the other way
around
When you calculate a matched odds ratio you only care about - ANS✔✔ discordant pairs!! (so
section B and C of your
