Objectives: To evaluate whether the relationship between sexual desire and quality of life (QOL) is moderated by sexual functioning in 91 men who had received treatment for localized prostate cancer within the past 18 months.
Methods: Items from the University of California, Los Angeles, Prostate Cancer Index and Expanded Prostate Cancer Index Composite were used to assess sexual factors, and the Functional Assessment of Cancer Therapy--General Module was administered to evaluate QOL. Education, income, and the Charlson comorbidity index were significantly related to QOL and controlled in all analyses. We tested a moderated regression model to predict QOL.
Results: Although a main effect was detected for sexual functioning, the interaction of sexual desire and sexual functioning added a significant amount to the explained variance in QOL. Post hoc tests of moderation revealed that men with lower sexual functioning had significantly lower QOL scores as the level of sexual desire increased, suggesting that desire in the absence of adequate functioning may result in poorer QOL. Additionally, a tendency was found for men with better sexual functioning to have higher QOL scores as the level of sexual desire increased.
Conclusions: The results of our study suggest that both sexual desire and sexual functioning are necessary for optimal QOL and highlight the utility of considering these two facets of sexuality independently to maximize the prediction of variance in QOL scores.