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Journal of Clinical Oncology, Vol 25, No 21 (July 20), 2007: pp. 3096-3100 © 2007 American Society of Clinical Oncology. DOI: 10.1200/JCO.2006.07.4955 Doctors and Patients Preferences for Participation and Treatment in Curative Prostate Cancer Radiotherapy
From the Departments of Radiation Oncology and Medical Technology Assessment, Radboud University Nijmegen Medical Center, Nijmegen; and Arnhems Radiotherapeutic Institute, Arnhem, the Netherlands Address reprint requests to Peep F.M. Stalmeier, PhD, Radboud University Nijmegen Medical Centre, MTA 138, PO Box 9101, 6500 HB Nijmegen, the Netherlands; e-mail: p.stalmeier{at}mta.umcn.nl
Purpose Physicians hold opinions about unvoiced patient preferences, so-called substitute preferences. We studied whether doctors can predict preferences of patients supported with a decision aid. Methods A total of 150 patients with prostate cancer facing radiotherapy were included. After the initial consultation, without discussing any treatment choice, physicians gave substitute judgments for patients' decision-making and radiation dose preferences. Physicians knew that several weeks later, patients would be empowered by a decision aid supporting a choice between two radiation doses involving a trade-off between disease-free survival and adverse effects. Subsequently, patient preferences for decision making (whether or not they wanted to choose a radiation dose) and for treatment (low or high dose) were obtained. The chosen radiation dose actually was administered.
Results Of the patients studied, 79% chose a treatment; physicians believed that 66% of the patients wanted to choose. Agreement was poor (64%; Conclusion Physicians had problems predicting the preferences of patients empowered with a decision aid. They slightly underestimated patients' decision-making preferences, and underestimated patients' preferences for the less toxic treatment. Counseling might be improved by first informing patients—possibly using a decision aid—before discussing patient preferences.
When patients have unvoiced preferences, the physician decides in the patients' best interest. To make this decision, physicians may try to imagine or judge the unvoiced preferences of patients. These so-called substitute judgments have been studied in end-of-life decision making. A general finding is that agreement between substitute and patient preferences is poor,1-5 suggesting that patients' needs and standards for informed consent may not be met. Other preferences such as preferences for decision making and treatment selection have been studied. Decision-making preferences reflect whether or not the patient wants to choose himself, or leave the decision to the physician. Treatment preferences reflect which medical treatment the patient wants. During the consultation, physicians hold opinions or substitute judgments about particular patient preferences. How are these opinions or substitute judgments formed? It is known that physicians may use their own preferences to form their substitute judgments.1,4 It is also likely that substitute judgments are formed by readily available patient characteristics such as age, education, and disease severity. For example, patients' decision-making preferences are positively associated with female sex and higher education, and decline with age and disease severity.6-9 It is plausible that these factors affect substitute preferences held by physicians. Substitute preferences are relevant for medical decision making. They are likely to steer the information detail and level of involvement that is offered to patients. In clinical practice, physicians may assume that they are a good judge of patients' preferences and preferred roles for decision making are not usually asked.10,11 Patients, in turn, ask few questions.12 Hence, the delivery of information is largely physician driven.13,14 The amount of information provided in practice is variable and often too incomplete to facilitate patient decision making.14,15 The variation in information suggests that physicians know in advance which patients want and which patients reject additional involvement after being informed further. Our study question is whether physicians indeed know these preferences. Given that the physician judgment about patients' involvement wishes precedes the provision of additional information, physicians' opinions were obtained before additional information was provided to patients. The preferences of patients were obtained after additional information was provided because the physician judges what the patient wants after the patient is informed further. In addition, factors affecting agreement between substitute and patient preferences were sought. The context was realistic; that is, the patients' choice was carried out.
Patients Between June 2003 and February 2005, all patients with a primary prostate tumor (T1-3, N0, M0) scheduled to undergo radiotherapy were included in this study.16,17 Exclusion criteria were mental disorders and insufficient knowledge of the Dutch language. Patients were enrolled in two locations: the Radboud University Nijmegen Medical Centre (Nijmegen, the Netherlands) and the Arnhems Radiotherapeutic Institute (Arnhem, the Netherlands).
Procedure In the second visit, on average 19 days after the first visit, the researcher interviewed the patients. In this interview, additional information was provided with a decision aid. After 2 days, decision-making and treatment preferences were confirmed by telephone and noted in the patient's medical record. These latter responses were used for the analyses described in this article. Subsequently, the preferred treatment (high- or low-dose radiation) was delivered. Physicians knew that patients' preferences were to be obtained after receiving the decision aid; physicians were familiar with the content of the decision aid.
Interview With Decision Aid The information was tailored to the patient characteristics in terms of prognostic risk and age category. Four separate information groups were distinguished. The first group consists of low-risk patients, who are characterized by a prostate-specific antigen (PSA) value less than 10 ng/mL, a Gleason score less than 7, and a T status of T1 or T2. The other patients were divided into age categories of younger than 57.5 years, 57.5 to 72.5 years, and older than 72.5 years. After receiving the decision aid, 10% of the patients requested and received an additional consultation with the physician to discuss the choice.
Measures
Preferences of Clinicians
Patient Variables Demographic variables and tumor characteristics. We collected self-report data on demographic variables (age, marital status, having [grand]children, working status, education, and religion). Tumor characteristics (T status, pretreatment PSA value, and Gleason score) were extracted from the medical records. Psychological and well-being variables. The Problem-Solving Decision-Making Scale19 assessed general decision-making preferences using two questions: "When the risks and benefits of radiotherapy are known to you, (1) who decides how acceptable those risks and benefits are to you, and (2) who decides on the choice?" The response scale ranged from "the doctor alone" (1), to "I alone" (5). The second question was also analyzed separately and used as a baseline decision-making preference. The personality traits autonomy and conscientiousness were assessed with five items each from a shortened version of a personality assessment instrument.20 General health in the previous week was assessed with an 11-point horizontal rating scale ranging from worst imaginable (0) to best imaginable health state (10). Hopelessness, avoidance, and fighting spirit were assessed with the Mental Adjustment to Cancer scale.21 Cancer worries were assessed with three questions: "Did you think of prostate cancer last week, did these thoughts affect your mood, and did these thoughts affect your daily activities?"22,23 Data were obtained on anxiety and depression by means of the Hospital Anxiety and Depression Scale.24 Prostate-specific quality of life was assessed by means of the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire PR25 prostate cancer module.25 It contains the following scales: urinary symptoms, bowel symptoms, treatment related adverse effects (bloatedness, hot flashes, edema, weight gain/loss), and sexual functioning. Knowledge. We asked patients to rate their knowledge (subjective knowledge) on prostate cancer and on the advantages and disadvantages of radiotherapy on a 10-point scale (ranging from "very poor" to "excellent"). Numeracy (ie, the ability to handle basic probability concepts) was assessed with three questions (eg, convert 1 in 1,000 to a percentage).26 Information. Patients were asked to rate their preference for information on a scale ranging from 0 ("I want to know nothing about my illness and treatment") to 10 ("I want to know as much as possible concerning my illness and treatment"). The patients' perception of the amount of information provided on prostate cancer and radiotherapy was rated on a 7-point scale ranging from "far too little information" to "far too much information."
Analysis Dichotimized variables associated with agreement at a level of P < .20 were included whenever possible as continuous variables in a hierarchical model for binary outcomes (procedure GENMOD; SAS software, version 8.2; SAS Institute, Cary, NC) with agreement as the dependent variable. This model accounted for patients clustering under physicians. Generalized estimating equations estimates were used to test for significance.
During the inclusion period, a total of 544 patients came for a consultation. More than 60% of these patients were not eligible because of local or distant metastases (n = 121), previous radical prostatectomy (n = 94), avoidance of external-beam radiotherapy (n = 36), cognitive/mental problems (n = 17), insufficient knowledge of the Dutch language (n = 10), and other reasons (n = 31). The remaining 200 patients were asked to participate in the study. One hundred fifty (75%) of these patients provided informed consent and were included in the study. Patient characteristics are categorized by informed consent in Table 1; the two groups did not differ. Physician characteristics are listed in Table 2. Because both centers were training hospitals, physicians differed in experience and number of patients seen for this study.
Decision-Making Preferences The results for decision-making preferences are listed in Table 3. Substitute preferences for decision making were available in 142 of 150 physician-patient pairs. The overall agreement in Table 3 is 64%. The agreement corrected for chance agreement, as expressed by , is 0.13 (P = .11). This indicates a poor agreement. Hierarchical analyses indicated that agreement for decision-making preferences improved with years of training of the radiation oncologist (odds ratio [OR] = 1.09 for each year; P = .02); agreement improved as patients became more hopeful (OR = 4.4 for each unit change; P = .001), hopelessness values varied between 1 and 3, and the possible range was 0 to 3. In physicians with more than 6 years of experience, overall agreement improved but chance corrected agreement remained poor ( = 0.26; P = .02). Similarly, in more hopeful patients, overall agreement improved to 75% but chance corrected agreement remained poor ( = 0.23; P = .02). Agreement was also better in patients with a PSA value greater than 10 ng/mL (OR = 2.1; P = .003) and in patients without bladder or bowel surgery (OR = 2.1; P = .03). Surprisingly, not even patients' own baseline decision-making preference agreed with their final choice behavior (agreement = 64%; = 0.13; P = .1).
Treatment Preferences Thirty-one patients did not want to choose, thus treatment preferences were not recorded; hence, agreement with physicians' substitute preferences was undefined. In addition, physicians did not provide substitute treatment preferences for 25 patients. As a result, agreement was undefined in 49 of 150 patients, leaving 101 physician-patient pairs (Table 4). The overall agreement was 60% ( = 0.20; P = .03), indicating that physicians are able to predict beyond chance which treatment the patient desires; however, the agreement was poor. Agreement was equally poor for male and female physicians. Hierarchical models for treatment preference agreement were not interpretable because the significance of determinants varied strongly depending on the variables included in the model.
Physicians' substitute treatment preferences were associated strongly with their own preferred treatment plan ( 2 = 10; P = .001; Table 5). Additional analyses (data not shown) showed that physicians' own preferences are driven by the medical status of the patient, such as higher T status. Male physicians were four times more likely to prefer the higher dose ( 2 = 15; P < .001).
Do physicians know the preferences of empowered patients? Decision-making and treatment preferences were assessed in physicians, and afterward in patients empowered by a decision aid. Slightly more patients (79%) wanted to decide themselves than the number expected by physicians (66%). Physicians could not indicate reliably which patients wanted to choose. Patients could not foresee their final preferences either. Regarding treatment preferences, patients favored the less toxic treatment (lower dose) more frequently (71%) than expected by physicians (51%). Physicians foresaw patients' treatment preferences to some extent, but agreement was poor. Physicians' own preference favored the lower dose in only 20% of the patients. Strong points of this study are that a concrete therapeutic choice was made by patients facing treatment, and that the treatment chosen was actually delivered. The agreement between physician and patient preferences was poor. This has been observed before.1-4,29-31 One could argue that the low agreement arises because the clinicians did not discuss the treatment choice with patients. This procedure, however, followed from our research rationale. In practice, physicians may vary information or involvement using their judgment of patient preferences for decision making. The judgment about patient preferences is made before extra information is provided to patients. This study intended to assess the accuracy of such prior judgments. Accordingly, patients' preferences were obtained after decision making was facilitated, and physicians' substitute preferences were measured before decision making was facilitated. Agreement was not uniformly poor. In more experienced physicians, agreement regarding decision making improved: this is a new finding, and it provides evidence for the claim of older physicians that experience improves their judgments of patients. In more hopeful patients, agreement also improved: this finding is also new and deserves additional interpretation. The rates of patient and substitute preferences in more or less hopeful patients were considered, but could not explain that agreement improves in more hopeful patients. An alternative explanation takes into account communication patterns in less hopeful patients. Less hopeful patients are more anxious and depressed. Such patients utter more concerns, requests, and receive more information, directives, empathy, and longer visits.32-35 Hence, such patients are more demanding,34 giving physicians less time to judge patient preferences, which in turn leads to a lower agreement. Other comments can be made. Physicians often believed they were guessing about patients' preferences. They would have preferred to use a "don't know" category while judging patients' decision-making and treatment preferences. "Don't know" responses, unfortunately, can not be analyzed, leading to a loss of valuable data. More importantly, by being forced to guess, some residual agreement might still be detected. In any case, varying the amount of information is a daily routine in clinical practice, so forcing a judgment is not unreasonable. One may argue further that the decision aid is new for physicians, thus confusing their judgment. One should consider, however, that several physicians were involved in the design of the decision aid. All physicians knew the content of the decision aid. These findings raise concerns about the provision of information and the incorporation of patient preferences in decision making. There are two implications. First, the findings illustrate that physicians need help to determine patient preferences. Physicians can discuss the preferences of the patient, but this is not always common practice. In such a discussion, decision aids may improve agreement36 because they present decision-making information in a format that patients understand, thus helping patients to develop and state their preferences. Second, patients could not foresee their own decision-making preferences. This raises the issue whether decision-making preferences should be obtained before (uninformed preferences) or after (informed preferences) information disclosure. The use of uninformed preferences overlooks the important role information or decision aids play in creating more active patients. Asking patient preferences after having shown a decision aid will satisfy standards for informed consent and patient autonomy.
The author(s) indicated no potential conflicts of interest.
Conception and design: Peep F.M. Stalmeier, Julia J. van Tol-Geerdink, Emile N.J.Th. van Lin, Henk Huizenga, Willem A.J. van Daal, Jan-Willem Leer Financial support: Peep F.M. Stalmeier, Henk Huizenga, Willem A.J. van Daal, Jan-Willem Leer Administrative support: Willem A.J. van Daal, Jan-Willem Leer Provision of study materials or patients: Julia J. van Tol-Geerdink, Emile N.J.Th. van Lin, Erik Schimmel Collection and assembly of data: Peep F.M. Stalmeier, Julia J. van Tol-Geerdink Data analysis and interpretation: Peep F.M. Stalmeier, Julia J. van Tol-Geerdink Manuscript writing: Peep F.M. Stalmeier, Julia J. van Tol-Geerdink Final approval of manuscript: Peep F.M. Stalmeier, Julia J. van Tol-Geerdink, Emile N.J.Th. van Lin, Erik Schimmel, Henk Huizenga, Willem A.J. van Daal, Jan-Willem Leer
Supported in part by a grant from the Dutch Cancer Society, Amsterdam, the Netherlands (Project No. KUN 2001-2379 and KUN 2005-3457). The funding agreement ensured the authors' independence in designing the study, interpreting the data, and writing and publishing the report. P.F.M.S. and J.J.V.T.-G. are supported by the sponsor. Presented at the 10th Biennial European Meeting of the Society for Medical Decision Making, June 11-13, 2006, Birmingham, United Kingdom. Authors' disclosures of potential conflicts of interest and author contributions are found at the end of this article. Clinical Trials Registry ISRCTN97145188.
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Copyright © 2007 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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