Substituting proxy ratings for patient ratings in cancer clinical trials: An analysis based on a Southwest Oncology Group trial in patients with brain metastases
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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.
- Moinpour CM, Feigl P, Metch B, Hayden KA, Meyskens FL Jr, Crowley J. Quality of life end points in cancer clinical trials: Review and recommendations. J Natl Cancer Inst 1989; 81: 485-495.
- Osoba D. Lessons learned from measuring health-related quality of life in oncology. J Clin Oncol 1994; 12: 608-616.
- Bernhard J, Cella DF, Coates AS, et al. Missing quality of life data in cancer clinical trials: Serious problems and challenges. Stat Med 1998; 17: 517-532.
- Troxel AB, Fairclough DL, Curran DL, Hahn EA. Statis-tical analysis of quality of life with missing data in cancer clinical trials. Stat Med 1998; 17: 653-666.
- Sprangers MA, Aaronson NK. The role of health care providers and significant others in evaluating the quality of life of patients with chronic disease: A review. J Clin Epidemiol 1992; 45: 743-760.
- Epstein AM, Hael JA, Tognetti J, Son LH, Conant L. Using proxies to evaluate quality of life. Med Care 1989; 27: S91-S98.
- Stephens R, Hopwood P, Girling DJ, Machin D. Randomized trials with quality of life endpoints: Are doctors’ ratings of patients’ physical symptoms interchangeable with patients’ self-ratings? Qual Life Res 1997; 6: 225-236.
- Sneeuw KC, Aaronson NK, Osoba David, et al. The use of significant others as proxy raters of the quality of life of patients with brain cancer. Med Care 1997; 35: 490-506.
- Pierre U, Wood-Dauphinee S, Korner-Bitensky N, Gayton D, Hanley J. Proxy use of the Canadian SF-36 in rating health status of the disabled elderly. J Clin Epidemiol 1998; 51: 983-990.
- Sneeuw KC, Aaronson NK, Sprangers MA, Detmar SB, Wever Lidwina DV, Schornagel JH. Value of caregiver ratings in evaluating the quality of life of patients with cancer. J Clin Oncol 1997; 15: 1206-1217.
- Sneeuw KC, Aaronson NK, Sprangers MA, Detmar SB, Wever Lidwina DV, Schornagel JH. Comparison of patient and proxy EORTC QLQ-C30 ratings in assessing the quality of life of cancer patients. J Clin Epidemiol 1998; 51: 617-631.
- Sloan JA, Loprinzi CL, Kuross SA, et al. Randomized comparison of four tools measuring overall quality of life in patients with advanced cancer. J Clin Oncol 1998; 16: 3662-3673.
- Spitzer WO, Dobson AJ, Hall J, et al. Measuring the quality of life of cancer patients. A concise QL-Index for use by physicians. J Chron Dis 1981; 34: 585-597.
- Slevin Ml, Plant H, Lynch D, Drinkwater J, Gregory WM. Who should measure quality of life, the doctor or the patient? Br J Cancer 1988; 57: 109-112.
- Nelson LM, Longstreth W, Koepsell TD, van Belle G. Proxy respondents in epidemiologic research. Epidemiol Rev 1990; 12: 71-86.
- Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 1: 307-310.
- Deyo RA, Diehr P, Patrick DL. Reproducibility and re-sponsiveness of health status measures. Statistics and strategies for evaluation. Controlled Clin Trials 1991; 12: 142S-158S.
- Lin LI. A concordance correlation coefficient to evaluate reproducibility. Biometrics 1989; 45: 255-268.
- Kramer MS, Feinstein AR. Clinical biostatistics LIV. The biostatistics of concordance. Clin Pharmacol Ther 1981; 29: 111-123.
- Rothman ML, Hedrick SC, Bulcroft KA, Hickam DH, Rubenstein LZ. The validity of proxy-generated scores as measures of patient health status. Med Care 1991; 29: 115-124.
- Marshall GN, Hays RD, Nicholas R. Evaluating agree-ment between clinical assessment methods. Int J Methods Psychiatr Res 1994; 4: 249-257.
- Prentice RL. Surrogate endpoints in clinical trials: Definition and operational criteria. Stat Med 1989; 8: 431-440.
- Fleming TR, Prentice RL, Pepe MS, Glidden D. Surrogate and auxiliary endpoints in clinical trials, with potential applications in cancer and AIDS research. Stat Med 1994; 13: 955-968.
- Wood-Dauphinee S, Williams JI. The Spitzer quality-life index: Its performance as a measure. In: Osoba D ed Effect of cancer on quality of life. Boston: CRC Press, Inc., 1991: 169-184.
- Cronbach LJ. Coefficient alpha and the internal structure of tests. Psychometrika 1951; 16: 297-334.
- Folstein MF, Folstein SE, McHugh PR. Mini-Mental State Examination (MMSE): A practical method for grading the cognitive state of patients for the clinician. J Psychiatr Res 1975; 12: 189-198.
- Folstein MF, Fetting JH, Lobo A, Niaz U, Capozzoli KD. Cognitive assessment of cancer patients. Cancer 1984; 53: 2250-2255.
- Altman DG, Bland JM. Measurement in medicine: The analysis of method comparison studies. Statistician 1983; 32: 307-317.
- Efron B, Tibshirani RJ. An introduction to the Bootstrap. New York: Chapman and Hall, 1993.
- Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics 1977; 33: 159-174.
- Cohen J. Weighted kappa: Nominal scale agreement with provision for scaled disagreement or partial credit. Psychol Bull 1968; 70: 213-220.
- Verbeke G, Molenberghs S. Linear Mixed Models in Practice. New York: Springer, 1997.
- Galecki A. A general class of covariance structures for two or more repeated factors in a longitudinal data analysis. Communications in Statistics: Theory and Methods 1994; 23: 3105-3119.
- Littell RC, Milliken FA, Stroup WW, Wolfinger RD®. SAS. Cary, NC: SAS Institute Inc., 1997.
- SAS Institute. SAS/STAT Software: Changes and Enhancements Through Release 6.12. Cary, NC: SAS Institute, Inc., 1997.
- Sneeuw K, Aaronson NK, de Haan R, Limburg M. Assessing quality of life after stroke: The value and limitations of proxy ratings. Stroke 1997; 28: 1541-1549.
- Hogan J, Laird N. Mixture models for the joint distribution of repeated measures and event times. Stat Med 1997; 16: 239-257.
- Hays RD, Vickrey B, Hermann B, et al. Agreement between self reports and proxy reports of quality of life in epilepsy patients. Qual Life Res 1995; 4: 159-168.
- Farrow DC, Samet JM. Comparability of information provided by elderly cancer patients and surrogates regard-ing health and functional status, social network, and life events. Epidemiology 1990; 1: 370-376.
- Humble CG, Samet JM, Skipper BE. Comparison of self-and surrogate-reported dietary information. Am J Epidemiol 1984; 119: 86-98.
- Armstrong BK, White E, Saracci R. Principles of Exposure Measurement in Epidemiology. Oxford: Oxford University Press, 1992; p 197.
- Substituting proxy ratings for patient ratings in cancer clinical trials: An analysis based on a Southwest Oncology Group trial in patients with brain metastases
Quality of Life Research
Volume 9, Issue 2 , pp 219-231
- Cover Date
- Print ISSN
- Online ISSN
- Kluwer Academic Publishers
- Additional Links
- Proxy measures
- Quality of life
- Industry Sectors
- Author Affiliations
- 1. Southwest Oncology Group Statistical Center, Seattle, WA, USA
- 2. Janssen Research Foundation, Titusville, NJ, USA
- 3. Freeman Health System, Joplin, MO, USA
- 4. University of Kentucky Medical Center, Lexington, KT, USA