Was a defined representative sample of patients assembled at a similar point in the course
of disease?
Was follow-up sufficiently long and complete?
Were objective and unbiased outcome criteria used?
Was there adjustment for important prognostic factors?
How likely are the outcomes over time?
How precise is the estimates of prognosis?
Were the study patients similar to my own?
Will the results lead directly to selecting therapy?
Are the results useful for counseling patients?
Reference: JAMA 1994; 272:234-237
Prognosis of a disease refers to its possible outcomes and the likelihood that each one will occur.
Prognostic Results are the number of events that occur over time, expressed in:
a. absolute terms: e.g. 5 years survival rate.
b. relative terms: e.g. risk from prognostic factor
c. survival curves: cumulative events over time
A Prognostic Factor is a patient characteristic that can predict that patient’s eventual outcome:
a. demographic: e.g. age, sex, race
b. disease specific: e.g. tumor stage
c. comorbid: other co-existing conditions
Articles that report prognostic factors often use two independent patient samples:
· the Derivation Set asks,
“What factors might predict patient outcomes?”
· the Validation Set asks,
“Do these prognostic factors predict patient outcomes accurately?”
· Explode Cohort Studies
· Prognosis (tw)
[see ACP J Club 1995 July-Aug; A12-A14]