Proxy assessment of health-related quality of life in african american and white respondents with prostate cancer: perspective matters.

According to the National Cancer Institute, there were 2 million prostate cancer survivors in the United States as of 2004, and the overall death rate from prostate cancer has dropped approximately 4% percent per year from 1994 to 2004.1 Family caregivers, particularly spouses, often have a major role with the patient and physician in shared decision making related to the management of localized prostate cancer. Management choices for localized prostate cancer include radical prostatectomy, watchful waiting, radiotherapy, and hormonal therapy,2,3 and impact on health-related quality of life (HRQL) can be a determining factor in choosing between treatment options.4,5 Not only do treatment alternatives for prostate cancer vary in their impact on the patient’s HRQL,6–18 but these choices can also affect the caregiver’s quality of life.19,20 In more advanced stages of the cancer, a family caregiver may become the primary source of information for clinicians on patient HRQL (ie, as a proxy). For these reasons, the caregiver’s perspective on the patient’s HRQL can be important to prostate cancer treatment decision making and management at any stage of the disease. Although numerous studies have explored the relationship between patient and proxy assessments of HRQL,21 the proxy viewpoint from which patient HRQL is rated has only recently received attention. A framework for understanding proxy perspectives delineated 2 proxy perspectives, where proxies can assess HRQL as they believe the patient would report on their own experience (ie, proxy-patient perspective), or assess HRQL from their own proxy viewpoint (ie, proxy-proxy perspective).22 The difference between HRQL assessments from the proxy-patient and proxy-proxy perspective has been referred to as the intraproxy gap, whereas the inter-rater gap refers to the difference between patient and proxy-patient perspective. Little is currently known about the magnitude of these differences in proxy perspectives or differences between patient and proxy perspectives that can serve as a clinical “red flag” for the treatment or care of the patient. In principle, when proxy assessment is performed for the purpose of eliciting surrogate judgments, the proxy-patient perspective is most appropriate. In this case, strong agreement between patient self-assessment and proxy assessment is desirable. In other circumstances, the proxy’s view of patient HRQL may be different from patient self-assessment yet provide valuable information about the patient that is potentially relevant to clinical decision making. Studies in pediatric oncology have found that HRQL ratings by children and their parents often do not agree yet each perspective provides valid and important information.23,24 HRQL assessments from the caregiver/proxy’s viewpoint can provide useful information that is complementary to the patient perspective, particularly in cases where the patient viewpoint prevents the patient from receiving adequate clinical care, such as when the patient neglects or denies their condition or illness. In such contexts, agreement between ratings from each perspective is not a requisite criterion for validity. In this study, we sought to empirically investigate aspects of a framework for understanding multiple proxy perspectives.22 The goal of this study was to compare HRQL assessments from the patient, proxy-patient, and proxy-proxy perspectives in prostate cancer. We tested whether assessments by patient self-report differed from proxy-patient and proxy-proxy ratings of HRQL by informal caregivers of prostate cancer patients. Drawing from the conceptual framework by Pickard and Knight,22 we hypothesized that the proxy-patient perspective would be closer to patient self-assessment than the proxy-proxy perspective. A secondary objective was to identify factors that explained the intraproxy gap (ie, differences in HRQL assessment between the proxy perspectives).