Use of verbal protocol analysis for identification of ADE signals.

We describe the use of verbal protocol analysis for evaluating the textual signals used by pharmacists for detection of adverse drug events (ADEs). "Think aloud" technique was used to gain insight into how pharmacists reason about ADE occurrence, when reading patient progress notes. We used case-scenarios for five ADEs consisting of information regarding patient history, medications, laboratory results, vital signs and patient progress notes. Pharmacists extensively used information present in the progress notes to make inferences about ADEs.