Assessing quality of life in patients with prostate cancer: a systematic and standardized comparison of available instruments
Methods: The Japanese version (version 1.2) of the UCLA PCI was developed through a process of translation, back-translation, and refinement after interviewing patients. Reliability and validity were examined for 125 Japanese patients with localized prostate cancer. The patients simultaneously responded to the Japanese version of the RAND 36-Item Health Survey (SF-36) and five representative questions from the International Index of Erectile Function (IIEF). Results: Internal consistency reliability was very high for both urinary and sexual function scales, and lower for bowel function. The test-retest reliability of the urinary and sexual function scales and the urinary bother scales was stable, while that of the bowel function and bother scales was relatively unstable. Sexual function scores did not correlate highly with sexual bother scores. Furthermore, poor sexual function and bother had little association with the SF-36 scores. Missing data as to urinary and bowel function/bother scales were minimal (0.8%–2.4%), while those for sexual function and bother were relatively high (4.8%–11.2%). Conclusions: The results of this pilot study, together with the previous American study, suggest ethnic or cultural difference in how impaired sexual function is integrated into overall QOL. A future cross-cultural comparative study using the UCLA PCI and SF-36 will provide useful information about the influence of cultural or ethnic differences on health-related QOL in prostate cancer patients.