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Abstract

In studies of the effect of cancer treatment in the advanced disease setting, researchers have attempted to avoid missing data for quality of life (QOL) assessments by either substituting proxy for patient assessments from the outset or by interspersing proxy measures when patients are unable to respond. Although poor agreement between patient and proxy assessments has been amply demonstrated in the literature, interest in using proxy measures persists. Completion of the Spitzer QL-Index by a small sample of patients with brain metastases and family member proxies provided data for evaluating the ability to substitute proxy for patient QOL assessments. These data cannot address treatment efficacy due to the modest sample size. Rather, the analyses serve to alert researchers to the important distinction (in a clinical trial setting) between agreement and the use of the proxy as a surrogate. We present several methods for evaluating the accuracy of proxy measures and for identifying other sources of error and bias that may vary with time or with treatment arm. Lin's concordance correlation coefficient suggests that proxies are generally a poor substitute for capturing a patient's perspective of his/her QOL. A longitudinal analysis suggests that the use of proxy rather than patient responses could lead to different conclusions concerning radiation therapy's effect on QOL.

Systematic review of caregiver responses for patient health-related quality of life in adult cancer care

“…A variety of generic tools ( N = 8, 25%) were used, including the Short Form-36 (SF-36) ( N = 2, 6%) [55, 56], the EuroQol five dimensions questionnaire (EQ-5D) ( N = 1, 3%) [33], the World Health Organisation Quality of Life Assessment-Bref (WHOQOL-BREF) ( N = 2, 6%) [36, 57], and the Primary Care Cooperative Information Project/World Organization of National Colleges, Academies, and Academic Associations of General Practices/Family Physicians (COOP/WONCA) ( N = 3, 9%) [32, 58, 59]. Of the papers using end-of-life specific tools ( N = 6, 19%), most employed the McGill Quality of Life (MQOL) ( N = 3, 9%) [29, 60, 61], followed by the Spitzer Quality of Life Index (SQLI) ( N = 2, 6%) [31, 62] and the Hospice Quality of Life Index (HQLI) ( N = 1, 3%) [27]. For those studies not restricted to spouses/partners as proxies, spouses usually comprised half or more of the proxies.…”

“…For the total score, where means for each group were provided [27, 62], the patient score was higher than the proxy score. One study using the Spitzer QLI [31] provided means for individual domains (which are items in the questionnaire), but no SDs; for both of these domains, the patient mean score was higher, indicating better QOL. However, as with other measures, the LOA were wide and encompassed a substantial proportion of the scale (Table 4).…”

Poor Accrual in Palliative Research Studies: An Update From the Rapid Response Radiotherapy Program

“…Also, as patients deteriorate, the family or caregiver will play a prominent role in proxy data collection [ 6 ]. The collection of proxy data represents a promising means to overcome significant drop-offs of data points for patients too ill to complete assessments, but patient-proxy agreement seems to vary by population and assessment tools [ 23 - 25 ]. Nevertheless, caregiver and family involvement is an important aspect of patient accrual.…”