Table 3 — Methodologic Rigor (articles classified according to the purpose categories shown in Table 2 were evaluated for methodologic rigor, except for cost and qualitative studies, and studies classified as something else)

Purpose Category
Definition
Causation (Etiology)
Observations concerned with the relationship between exposures and putative clinical outcomes;Data collection is prospective;Clearly identified comparison group(s);Blinding of observers of outcome to exposure.
Prognosis
Inception cohort of individuals all initially free of the outcome of interest;Follow-up of ³80% of patients until the occurrence of a major study end point or to the end of the study; Analysis consistent with study design.
Diagnosis
Inclusion of a spectrum of participants;Objective diagnostic (“gold”) standard OR current clinical standard for diagnosis;Participants received both the new test and some form of the diagnostic standard;Interpretation of diagnostic standard without knowledge of test result and vice versa;Analysis consistent with study design.
Therapy
Random allocation of participants to comparison groups;Outcome assessment of at least 80% of those entering the investigation accounted for in 1 major analysis at any given follow up assessment;Analysis consistent with study design.
Economics
Question is a comparison of alternatives;Alternative services or activities compared on outcomes produced (effectiveness) and resources consumed (costs);Evidence of effectiveness must be from a study of real patients that meets the above-noted criteria for diagnosis, treatment, quality improvement, or a systematic review article; Effectiveness and cost estimates based on individual patient data (micro-economics); Results presented in terms of the incremental or additional costs and outcomes of one intervention over another;Sensitivity analysis if there is uncertainty.
Clinical Prediction Guides
Guide is generated in one or more sets of real patients (training set); Guide is validated in another set of real patients (test set).
Reviews
Statement of the clinical topic; Explicit statement of the inclusion and exclusion criteria;Description of the methods;³ 1 article must meet the above noted criteria.