Evidence-based medicine: Classifying the evidence from clinical trials – the need to consider other dimensions

Table 4 Summary of components to consider when evaluating the quality of evidence from research

Study design	Randomized
	Allocation concealment
	Blinding (if possible)^a
	Clinically important and objective primary outcome
	Beta-error^b
	Multi-center
Study conduct	Intention-to-treat analysis
	Follow-up or attrition rate
	Completion to planned numbers
Study findings	Biological plausibility
	Strength of estimate of effect
	Precision of estimate of effect
	Observed event rate
Study applicability	Consistency across similar studies
	Reproducibility
	Generalizability

^aBlinding may not be possible in device or protocol/process trials. ^bAdequately powered, appropriate estimate of control event rate and relative or absolute reduction in clinically important primary outcome.

ISSN: 1364-8535