1050 Validation of the quality of life-radiation therapy instrument (QOL-RTI) in patients receiving definitive radiation therapy for locally advanced prostate cancer

Abstract

Purpoealobjectfve: Ths incidence of prostate cancer has tripled over the last 10 years, co&led over the last four years and continues to increase. A common method of treating prostate cancer is with external bsam radiotherapy with or without hormones. Accurate and comprehensive documentation through prospective studies with long term follow-up is necessary to reduce the negative impact of treatment on a patient% quality of life. While it is increasingly recognized that radiation therapy tmatment for prostate cancer may result in permanent alteration of the patient’s quality of life, the extent and timing of this change in quality of life has not been adequately investigated in a comprehensive and prospective manner. Furthermore, there are limited instruments developed for use with patients undergoing definitive radiotherapy. The purpose of this paper is to report on the validation of the Quality of Lie Radiation Therapy Instrument (QOL-RTI), a 24-item visual analogue general quality of life tool developed for use with patients receiving radiotherapy. Materials & Methods: Health related quality of life was assessed in a prospective study of 62 patients treated with either combined hormonal therapy (HT) plus external beam radiotherapy (EBRT) or EBRT alone for locally advanced prostate cancer. Quality life was measured prospectively before, during, and after radiation therapy. Results: The estimeted reliability of the subscales was assessed with coefficient alpha which ranged from 0.57 to 0.66. Internal consistency was calwlated using initial questionnaires for tha entire sample, yielding a Cronbach’s alpha of 0.82. Test-retest produced a correlation coeffitient of 0.75 (p<O.OOOl) [n=60). Construct validity was assessed by a repeated measures design to look for time effect, group effect, group and time interaction effect. We examined quality of life total scores, subscale total scores and performance status scores for patients who were treated with HT+ EBRT and patients who received EBRT alone, at various time frames before, during and after treatment. Analysis of Variance showed evidence of time effect in two subscales of the instrument: functional health (p<O.O002) and emotional/psychological functioning (p~O.007). Kamofsky Performance Status (KPS) scores were also significant for the time effect. These findings suggest that the QOL-RTI is capable of detecting changes in certain domains of quality of life in this population. There was no evidence of treatment group effect or time/group (treatment) interaction effect for all the above variables. Conclusion: These findings suggest that the QOL-RTI is a reliable and valid instrument for use with prostate cancer patients. The data also suggests that the salience of different domains of quality of life varies in this patient population and it also appears to suggest the need for a disease specific module for use with the QOL-RTI in prostate cancer patients. Additionally, several methodological issues related to administration and data management for the visual analogue tool are discussed. The experience in this study and in a previous pilot study have inspired new directions in the further development of the QOL-RTI for other sites.