Patient expectancy and post-chemotherapy nausea : a meta-analysis

Post-chemotherapy nausea remains a significant burden to cancer patients. While some studies indicate that expecting nausea is predictive of experiencing nausea, there are a number of conflicting findings. The purpose of this study was to conduct a meta-analytic review to determine the strength of the relationship between expectancy and post-chemotherapy nausea. The findings from 17 relevant studies (n=2,400) identified through systematic searches of Medline, PsycInfo, and Cinhal were analyzed using a combination of meta-analytic techniques. Overall, there was a robust positive association between expectancy and post-chemotherapy nausea (ESr=0.18, equivalent to Cohen’s d=0.35), suggesting that patients with stronger expectancies experience more chemotherapy-induced nausea. Although weaker associations were found in studies employing multivariate analysis, specifically controlling for a history of nausea, and involving breast cancer patients, none of the moderators assessed were statistically significant. These findings suggest that patient expectancies may contribute to post-chemotherapy nausea and that expectancy-based manipulations may provide a useful intervention strategy.