Defining anticipatory nausea and vomiting: differences among cancer chemotherapy patients who report pretreatment nausea.

It is important to distinguish patients whose reports of pretreatment nausea and vomiting reflect classically conditioned anticipatory nausea and vomiting (ANV) from those whose reports reflect the influence of other pharmacological and psychological factors. Therefore, Andrykowski (J. Behav. Med. 9: 33-41, 1986) has suggested that only patients who report pretreatment nausea on Day 1 of a chemotherapy cycle be considered to have developed ANV. As part of a prospective, longitudinal investigation of side effects associated with cancer chemotherapy, three groups of patients were identified: those who (a) never reported pretreatment nausea (noPTN), (b) reported pretreatment nausea but never prior to a Day 1 infusion (PTN), and (c) reported pretreatment nausea prior to a Day 1 infusion (PTND1). Discriminant analysis revealed that the PTN and noPTN groups did not differ, while both differed from the PTND1 group, particularly with respect to factors presumed to facilitate classical conditioning. The results justify excluding PTN patients from the criterion group of patients considered to have developed ANV.