wash-in period
A stabilization period at the beginning of a study where patients receive consistent treatment before randomization.
Full Definition
A wash-in period, also called a run-in or stabilization period, is a phase at the start of a clinical trial during which all participants receive the same treatment or placebo before being randomized to different study arms. This period serves multiple purposes: it allows for baseline stabilization, helps identify patients who respond well to placebo (who may then be excluded), ensures medication compliance, and can help reduce the variability in the study population. In psychiatric research, wash-in periods are particularly important because of the high placebo response rates and the need to establish stable baseline symptom levels.
Usage
Usage note: Distinguish carefully from 'washout period' which involves discontinuing medications.
In Context
- "Following a 2-week wash-in period on placebo, eligible patients were randomized to active treatment." — study methodology
- "The wash-in phase allowed researchers to identify high placebo responders for exclusion." — trial design rationale