Medical Diagnostic Tests: A Review of Test Anatomy, Phases, and Statistical Treatment of Data
Table 1
Anatomy on phases of a diagnostic test.
Phase
What?
Design
I
Determination of normal ranges (pharmacokinetics, pharmacodynamics, and safe doses)
Observational studies on healthy subjects
II
Evaluation of diagnosis accuracy
Case-control studies on healthy subjects and subjects with the known (by a gold standard test) and suspected disease of interest (i) Phase IIa: healthy subjects and subjects with the known disease of interest, all diagnosed by a gold standard method (ii) Phase IIb: testing the relevance of the disease severity (evaluate how a test works in ideal conditions) (iii) Phase IIc: assess the predictive values among subjects with suspected disease
III
Evaluation of clinical consequences (benefic and harmful effects) of introducing a diagnostic test
Randomized control trials, randomization determine whether a subject receive or not the diagnosis test
IV
Determination of the long-term consequences of introducing a new diagnostic test into clinical practice
Cohort studies of consecutive participants to evaluate if the diagnostic accuracy of a test in practice corresponds to predictions from systematic reviews of phase III trials
