2017 Nashville

Question 1

Power calculation

Answer 1

estimates the number of subjects required to find a clinically significant difference between exposure groups

Question 2

Confounding factors

Answer 2

factors that confuse analytical study results because they influence both independent and dependent variables.

Question 3

prevalence

Answer 3

number of cases in the population of interest at a given time

Question 4

point prevalence

Answer 4

prevalence at once specific time

Question 5

period prevalence

Answer 5

prevalence of a condition over a specific defined time period

Question 6

incidence

Answer 6

number of new cases that develop a condition over a defined time period, none of which had the condition at the instant the defined time period begins.

Question 7

incidence proportion also called cumulative incidence

Answer 7

proportion of animals that developed a condition over that period

Question 8

incidence rate

Answer 8

takes into consideration the time component; ints numerator is the same as in incidence proportion ( the number of patients who developed the condition) but the denominator is different and is expressed in # patients x time at risk (patient-hours or patient-days etc)

Question 9

Hypothesis-Generating Studies

Answer 9

Observational Study Designs:
Descriptive
Analytical
Case-control

Question 10

Descriptive studies

Answer 10

Case Report: description of singe case with a novel course of a known disease

• can provide information about emerging diseases or new diagnostic or treatment options
• information cannot be generalized to other individuals

Case Series:
description of multiple cases without a comparison group

Same advantages and disadvantages as case report

Question 11

Analytical Studes

Answer 11

compare > or = to 2 groups and allow associations between variables to be made

Cross-sectional study: all measurements taken at a single time point without a flow up period of a population of animals divided into those affected by X condition and those unaffected

Variables can be sex, breed, other putative risk factors and are compared between affected and unaffected groups.

Variables and contain X are generally expressed as an odds ratio.

They can determine prevalence but not incidence since they are a snapshot in time

Case-control study: ALWAYS retrospective and longitudinal as they follow subjects over time. Good for studying rare diseases or outcomes because the researcher first identifies affected cases and selects the matched control after.
No prevalence or incidence information can be generated and by design only a single outcome can be investigated.

Question 12

Hypothesis-Testing Clinical studies

Answer 12

ALL ARE ANALYTICAL

Observational study:

Cohort study: divide an at-risk population into groups based on their exposure vs non exposure to X putative causal factor and flow them over time.

Can be prospective or retrospective
Prospective can determine incidence

Cohorts are more statistically reliable than case control studies as pertains to determination of causality because the researcher starts with the putative causal factor and looks forward for the outcome of interest

Interventional Studies:
Controlled clinical trial: determine superiority of a treatment or intervention by comparing outcomes between groups that receive different assigned treatments.

Randomized and Nonrandomized