Module 9: Evidence about Prognostic Factors

A prognosis tells us what information?

• Which outcome could happen

• The likelihood that outcomes will happen

• The time-frame for outcome development

• Develop POC and set goals

What is a prognostic indicator?

A variable that may predict any type of event or outcome

What is a risk factor?

A factor that may predict adverse events or outcomes

What is the definition of Relative Risk?

• "What is the risk of this outcome occurring"

• Ratio of risk for developing the adverse outcomes in patients with the risk factor vs patients without the risk factor

• (Comparable to odds ratio BUT depends on incidence of outcomes in both groups)

What is the definition of Odds Ratio?

• "What are the odds of this outcome occurring"

• The odds that an individual with the prognostic/risk factor will develop the variable of interest

How is relative risk calculated?

What does a Relative Risk of >1 indicate?

Increased risk of an adverse outcome

What does a Relative Risk of <1 indicate?

Decreased risk of the adverse outcome

How is the Odds Ratio (OR) calculated?

If the odds ratio is negative, how are the scores interpretted?

OR > 1: odds are in favor of an adverse outcome (problem will develop)

OR < 1: odds are against an adverse outcome (prognostic factor is protective against the problem)

If the odds ratio is positive, how are the scores interpretted?

OR > 1: odds are in favor of an positive outcome

OR < 1: odds are against an positive outcome (prognostic factor is harmful)

What does it mean if an odds ratio is 1.0?

Represnets a 50:50 chance of increasing or decreasing the odds that the outcome will occur?

What does it mean if the Relative Risk (RR) is 1.0?

Represents a 50:50 chance that increasing or decreasing the risk that the outcome will occur

What is an inception cohort?

Subjects enrolled in a study before they develop the outcome of interest