Transcript Table: Prognosis I. Are the results in the study valid? Primary Guides

Prognosis study EBM questions
Prognostic factors
Characteristics of patient that may predict
eventual outcome
Several types:
demographic (eg age)
disease-specific (eg tumor stage)
comorbid (eg other conditions accompanying the
disease in question)
Prognostic factors
Can predict any outcome, whether good (eg cure or
survival) or bad (eg death or complication).
Need not necessarily cause the outcomes – just be
associated with them strongly enough to predict their
development.
Are distinguished from risk factors = patient
characteristics associated with initial development of the
disease
Example: smoking is an important risk factor for lung
cancer, but is not as important a prognostic factor as
tumor stage in someone who has lung cancer.
Are the results
in the study valid?
Was there a representative and well-defined
sample of patients at a similar point in the course
of the disease?
 Was follow-up sufficiently long and complete?
 Were objective and unbiased outcome criteria
used?
 Was there adjustment for important prognostic
factors?

What are the results?
How large is the likelihood of the outcome
event(s) in a specified period of time?
How precise are the estimates of likelihood?
Will the results help me in caring
for my patients?
Were the study patients similar to my own?
Will the results lead directly to selecting or
avoiding therapy?
Are the results useful for reassuring or
counseling patients?