Interaction between patient and test administrator may influence the results of edrophonium provocative testing in patients with noncardiac chest pain.

Abstract

Edrophonium is a widely used provocative agent in the evaluation of noncardiac chest pain, with reported positivity rates of 30-55%. The influence of a subjective response and psychological factors on test results have not been examined previously. A retrospective analysis was performed to compare positivity rates for three physicians in the same laboratory. This was followed by a prospective study of 62 patients with noncardiac chest pain randomized to two groups. Group 1 patients were told that intravenous medication was given to observe changes in the tracing. Group 2 patients were told that the injection was to elicit their usual pain. During the 2-yr retrospective review, 260 patients were tested. The positivity rate varied from 31.1% with physician A to 20.2% with physician B and 7.5% for physician C (p = 0.001 for A vs. C, and p = 0.04 for B vs. C). In the prospective study, chest pain was elicited in nine of 62 patients (14.5%). Two of the 29 patients in group 1 (6.9%) and seven of 33 patients in group 2 (21.2%) contributed to this result. Contraction amplitude and duration increased similarly in all groups. These data suggest that edrophonium testing may be influenced by coaching, that manometric changes are similar in positive and negative tests, and that the prevalence of positive tests is lower than previously reported.