DUMC Library: Evaluating a PROGNOSTIC article

Validity issues

1. Was the sample of patients representative?
2. Were the patients significantly homogeneous with respect to prognostic risk?
3. Was follow-up complete?
4. Were objective and unbiased outcome criteria used?

What are the results?

1. How likely are the outcomes over time?
2. How precise are the estimates of likelihood?

How can I apply the results to patient care?

1. Were the study patients and their management similar to those in my practice?
2. Was the follow-up sufficiently long?
3. Can I use the results in the management of patients in my practice?

Results

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

• absolute terms: e.g. 5 year survival rate
• relative terms: e.g. risk from prognostic factor
• survival curves: cumulative events over time

• demographic: e.g. sex, age, race
• disease-specific: e.g. tumor stage
• comorbidity: other co-existing conditions

Articles that report prognostic factors often use two independent patient samples:

• derivation sets asks - "what factors might predict patient outcomes?"
• validation sets ask - "do these prognostic factors predict patient outcomes accurately?"

Finding articles about a prognosis study

• Use Clinical Queries for Prognosis
• Search terms: cohort studies OR prognosis (MeSH term)

• explode cohort studies/ (MeSH)
• prognosis.mp. (MeSH or textword)
• EBM Filter under Saved Searches: EBMPRO1 (comprehensive/sensitivity)
• EBM Filter under Saved Searches: EBMPRO2 (relevance/specificity)

References:

• JAMA 1994 272:234-237
• ACP Journal Club 1995 July-Aug; A12 - A14

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