Urinary incontinence (UI) is a common symptom in patients with prostate cancer following various treatments. Despite the recognition of the negative impact of severity of UI on quality of life (QoL) in patients with prostate cancer after treatment, treating UI symptoms may not necessarily improve the QoL of the patients with UI. Evidence indicated that self-reported UI and subjective wetting outcome have a negative effect on patients’ QoL; however, the current gold standard assessment for UI is only to reduce the frequency of UI episodes or pad weight for medical solutions. According to the emotional factors, such as psychological distress is involved in perceived severity of UI, it might be inadequate in measuring symptom distress or its interference with daily life in patients with UI. However, little is known about the moderating role of depressive symptoms underlying these relations. 

Hypothesis: Depressive symptoms moderated the direct and indirect effects of the relationship of patient-perceived severity of UI and quality of life in prostate cancer patients after treatment.

Aim: To determine whether the perceived severity of UI can predict QoL following treatments in patients with prostate cancer after adjustment of covariates and then to explore whether depressive symptoms moderated the direct and indirect effects of the relationship of patient-perceived severity of UI and QoL in prostate cancer patients after treatment. In addition, to examine the differences in QoL between the radical prostatectomy (RP) group and the non-radical prostatectomy (non-RP) group.

Study design: A cross-sectional study with outpatients with prostate cancer after treatment was conducted.

Materials and methods: All patients with prostate cancer who had received treatment for prostate cancer, aged ≥ 20 years, and could read and communicate in Mandarin Chinese or Taiwanese were eligible for enrollment in this study. Patients who had cognitive impairments, resided in institutions, had a major comorbid terminal illness, or receiving hormone therapy treatment were excluded. Six scales were administered to collect data: the Taiwan version of The International Physical Activity Questionnaire - Short Form, International Index of Erectile Dysfunction questionnaire, the Chinese version of the Cancer Fatigue Scale, the Chinese version of the Beck Depression Inventory, Second Edition, the Chinese version of the Beck Anxiety Inventory, and the Chinese version of the incontinence quality of life questionnaire. Multiple linear regression analysis was used to identify independent predictors of QoL. A moderated mediation analysis was conducted to test the model obtained from prostate cancer patients after treatment. In addition, Mann-Whitney U-test was used to examine the median of QoL comparison between two groups for samples that were not normally distributed. All analyses were analyzed using SPSS 19.0 and the model was analyzed using PROCESS v3.3.

Results: Among the 66 patients with mean age of 72.12 years, most patients had localized cancer (73.0%) and had undergone radical prostatectomy (65.2%). In multivariate modeling, the most powerful predictor of QoL was depression (32.0%). Average monthly outcome more than 100000 was also a significant predictor. The patients’ perceived severity of UI was statistically significant as an independent predictor of QoL. Together, these variables explained 47% of variance in I-QoL among patients with prostate cancer after treatment. The moderated mediation analysis revealed that the depressive symptoms significantly moderated the conditional indirect effect of quality of life through patient-perceived severity of UI (Index of moderated mediation: B = -0.85, SE = 2.40, 95% bootstrapped confidence interval: −7.002, −2.780) (Table 1).  Although all the mean scores of I-QOL and the three subscales in the non-RP group were higher than those of the RP group, only in the psychosocial impact domain the mean score in the non-RP group was significantly higher than that in the RP group (p < 0.05) (Table 2).

The patients’ perceived severity of UI was an independent predictor of QoL and the patient-perceived severity of UI was modeled to exert an effect on quality of life indirectly through depressive symptoms as well as directly, with moderation of the effect of depressive symptoms on quality of life. Prostate cancer patients with non-RP treatment have higher scores in the psychosocial impact domain of quality of life than that in the those who with RP.

According to our current study, to combine the evaluation of the psychological function with the standard assessments in patients with prostate cancer may be more relevant in accurate appraisal for post-treatment UI and QoL. In further study, patients’ perceptions of treatment success and satisfaction should be emphasized in the assessment method.

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