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Prognosis Article Appraisal Guide

Understanding an Article on Prognosis

The prognosis of a disease refers to its possible outcomes and the likelihood that each one will occur.

A prognostic factor is a patient characteristic that can predict that patient's eventual outcome:

blue arrowdemographic: e.g. age
blue arrowdisease-specific: e.g. tumor stage
blue arrowcomorbid: other conditions present

Prognostic results are the number of events that occur over time, expressed in:

blue arrowabsolute terms: e.g. 5 year survival rate
blue arrowrelative terms: e.g. risk from prognostic factor
blue arrowsurvival curves: cumulative events over time

Questions to Ask Yourself

Are the results valid?

1. Was there a representative and well-defined sample of patients at a similar point in the course of disease?

blue arrowInclusion and exclusion criteria?
blue arrowSelection biases?
blue arrowStage of disease?


2. Was follow-up sufficiently long and complete?

blue arrowReasons for incomplete follow-up?
blue arrowPrognostic factors similar for patients lost- and not lost-to-follow-up?

What are the results?

1. How likely are the outcomes over time?

blue arrowSurvival curves (Kaplan-Meier)?

2. How precise are the estimates of likelihood?

blue arrowConfidence intervals?


3. Did the study have a sufficiently large sample size?

Vanderbilt- Power and Sample Size Calculator

Will the results help me in patient care?

1. Were the study patients similar to my own?

red ball imagePatients similar for demographics, severity, co-morbidity, and other prognostic factors?
red ball imageCompelling reason why the results should not be applied?

2.Will the results lead directly to selecting therapy?


3. Are the results useful for reassuring patients?