Baseline

<B>1.</B> Information gathered at the beginning of a study from which variations found in the study are measured.<BR><B>2.</B> A known value or quantity with which an unknown is compared when measured or assessed.<BR><B>3.</B> The initial time point in a clinical trial, just before a participant starts to receive the experimental treatment which is being tested.

At this reference point, measurable values such as CD4 count are recorded.

Safety and efficacy of a drug are often determined by monitoring changes from the baseline values