Purpose: We examined the extent of agreement in health related quality of life ratings provided by patients with metastatic prostate cancer and their spouses. This agreement is important for determining the feasibility of using spouses as potential proxy raters in quality of life studies in this patient population.
Materials and methods: The study sample consisted of 72 pairs of patients with metastatic prostate cancer in remission or progression and their spouses. Patients and spouses independently completed the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-C30 and a prostate cancer specific questionnaire module. Together the 2 questionnaires assess a wide range of symptoms and functional limitations for a total of 21 quality of life outcomes.
Results: For 5 of the 21 patient-proxy comparisons we noted systematic differences in the mean score with spouses rating more impairment in patients than patients indicated. Most patient-proxy correlations were 0.40 to 0.75, indicating moderate to good agreement in patient and spouse ratings. A low patient-proxy correlation of less than 0.40 was noted only for the 2 measures of sexual function.
Conclusions: Our findings suggest that the spouses of men with metastatic prostate cancer evaluate with a fair degree of accuracy how patients experience physical and psychosocial functioning, symptoms and overall quality of life. However, caution should be exercised when relying on proxy raters for assessing sexual functioning and satisfaction.