Self-assessed health-related quality of life in men who have completed radiotherapy for prostate cancer: instrument validation and its relation to patient-assessed bother of symptoms.

The purpose of this study was to develop a psychometrically reliable and valid questionnaire to assess the disease-specific dimensions of health-related quality of life (HRQOL) in the urinary function (UF), bowel function (BF), and sexual function (SF) domains of prostate cancer (PCa) patients treated with radiation therapy. Patients were given a six-page questionnaire using Likert-type questions assessing three HRQOL dimensions during their follow-up visits after completing radiotherapy. Scales created from an earlier study were utilized and tested for reliability and validity. In addition, we assessed the relationship between these dimensions and the degree to which a decreased HRQOL increases the degree to which patients feel bothered about their symptoms. There are two scales within each dimension: BF, Urgency and Daily Living; UF, Urgency and Weakness of Stream; SF, Interest/Satisfaction and Impotence. Internal-consistency reliability coefficients (Cronbach's alpha) for the proposed scales range from 0.48 to 0.92, and all item-scale correlations and divergence correlations validate the use of the scales, ranging from 0.49 to 0.89. The validity of these scales is also confirmed by the rising median scores with rising reported levels of patient-perceived "bother." The different dimensions have differing quantitative influences on patients. We have developed a prostate-specific HRQOL instrument that is an adequate and suitable tool for measuring HRQOL along three distinct dimensions for patients who have completed radiotherapy for PCa. Psychometric standards for reliability and validity were met for the proposed scales. Moreover, positive correlations were found between these dimensions and how bothered patients were by their symptoms, suggesting important relationships that should be followed in PCa patients after radiotherapy. Certain scales have strong influences on patient-perceived "bothersomeness" of symptoms, such as loss of control of BF, urgency of BF, urgency of urination, and level of interest/satisfaction in sex. Compared to our earlier study on patients being treated with radiotherapy for PCa, this study produced very similar results. With some modification, the same questionnaire could be used for both groups of patients. Int. J. Cancer (Radiat. Oncol. Invest.) 90, 163-172 (2000). Copyright 2000 Wiley-Liss, Inc.