before-and-after trial

(redirected from before-and-after design evaluation)

before-and-after trial

An investigation of therapeutic alternatives in which patients from time-period A, and under treatment-regimen A, are compared to patients at a later time B under treatment B. If the disorder is not fatal and treatment A is not curative, the same individuals may be studied in both the before and after periods, strengthening the study design by increased the comparability of the 2 groups for the 2 periods; a reflexive design in which only a few before-intervention and after-intervention measures are taken.