Table 3.

Hierarchies of data sources and study designs for the components of evaluation

Levela	Analytic validity	Clinical validity	Clinical utility
1	Collaborative study using a large panel of well characterized samples	Well-designed longitudinal cohort studies	Meta-analysis of randomized controlled trials (RCT)
	Summary data from well-designed external proficiency testing schemes or interlaboratory comparison programs	Validated clinical decision ruleb
2	Other data from proficiency testing schemes	Well-designed case-control studies	A single randomized controlled trial
	Well-designed peer-reviewed studies (e.g., method comparisons, validation studies)
	Expert panel reviewed FDA summaries
3	Less well designed peer-reviewed studies	Lower quality case-control and cross- sectional studies	Controlled trial without randomization
		Unvalidated clinical decision ruleb	Cohort or case-control study
4	Unpublished and/or non-peer reviewed research, clinical laboratory, or manufacturer data	Case series	Case series
	Studies on performance of the same basic methodology, but used to test for a different target	Unpublished and/or non-peer reviewed research, clinical laboratory or manufacturer data	Unpublished and/or non-peer reviewed studies
		Consensus guidelines	Clinical laboratory or manufacturer data
		Expert opinion	Consensus guidelines
			Expert opinion

^aHighest level is 1.

^bA clinical decision rule is an algorithm leading to result categorization. It can also be defined as a clinical tool that quantifies the contributions made by different variables (e.g., test result, family history) in order to determine classification/interpretation of a test result (e.g., for diagnosis, prognosis, therapeutic response) in situations requiring complex decision-making.⁵⁵