Test-retest reliabilities of two treatment-preference instruments in measuring utilities

Live liver donors' risk thresholds: risking a life to save a life

BACKGROUND

There is still some controversy regarding the ethical issues involved in live donor liver transplantation (LDLT) and there is uncertainty on the range of perioperative morbidity and mortality risks that donors will consider acceptable.

METHODS

This study analysed donors' inclinations towards LDLT using decision analysis techniques based on the probability trade-off (PTO) method. Adult individuals with an emotional or biological relationship with a patient affected by end-stage liver disease were enrolled. Of 122 potential candidates, 100 were included in this study.

RESULTS

The vast majority of participants (93%) supported LDLT. The most important factor influencing participants' decisions was their wish to improve the recipient's chance of living a longer life. Participants chose to become donors if the recipient was required to wait longer than a mean ± standard deviation (SD) of 6 ± 5 months for a cadaveric graft, if the mean ± SD probability of survival was at least 46 ± 30% at 1 month and at least 36 ± 29% at 1 year, and if the recipient's life could be prolonged for a mean ± SD of at least 11 ± 22 months.

CONCLUSIONS

Potential donors were risk takers and were willing to donate when given the opportunity. They accepted significant risks, especially if they had a close emotional relationship with the recipient.

Comparing clean intermittent catheterisation and transurethral indwelling catheterisation for incomplete voiding after vaginal prolapse surgery: a multicentre randomised trial

OBJECTIVE

To compare clean intermittent catheterisation with transurethral indwelling catheterisation for the treatment of abnormal post-void residual bladder volume (PVR) following vaginal prolapse surgery.

DESIGN

Multicentre randomised controlled trial.

SETTING

Five teaching hospitals and one non-teaching hospital in the Netherlands.

POPULATION

All patients older than 18 years experiencing abnormal PVR following vaginal prolapse surgery, with or without the use of mesh. Exclusion criteria were: any neurological or anxiety disorder, or the need for combined anti-incontinence surgery.

METHODS

All patients were given an indwelling catheter directly after surgery, which was removed on the first postoperative day. Patients with a PVR of more than 150 ml after their first void were randomised for clean intermittent catheterisation (CIC), performed by nursing staff, or for transurethral indwelling catheterisation (TIC) for 3 days.

MAIN OUTCOME MEASURE

Bacteriuria rate at end of treatment.

RESULTS

A total of 87 patients were included in the study. Compared with the TIC group (n = 42), there was a lower risk of developing bacteriuria (14 versus 38%; P = 0.02) or urinary tract infection (UTI; 12 versus 33%; P = 0.03) in the CIC group (n = 45); moreover, a shorter period of catheterisation was required (18 hours CIC versus 72 hours TIC; P < 0.001). Patient satisfaction was similar in the two groups, and no adverse events occurred.

CONCLUSION

Clean intermittent catheterisation is preferable over indwelling catheterisation for 3 days in the treatment of abnormal PVR following vaginal prolapse surgery.

Methodologic evaluation of adaptive conjoint analysis to assess patient preferences: an application in oncology

BACKGROUND

Adaptive conjoint analysis (ACA) is an individually tailored preferences elicitation technique that mimics actual decision-making processes by asking participants to make trade-offs between the various dimensions that underlie decision problems. ACA is increasingly applied in patient preferences assessments but formal evaluation of its validity and reliability is lacking.

OBJECTIVE

To investigate ACA's validity and reliability in elicitation of treatment outcome preferences.

METHODS

Sixty-eight disease-free rectal cancer patients, treated with surgery with or without preoperative radiotherapy were asked to complete exercises to assess their preferences for radiotherapy [using the treatment trade-off method (TTM)] and for key outcomes associated with radiotherapy (using ACA). We assessed (i) rank ordering of ACA-derived outcome-probability utilities, (ii) compensatory decision making, (iii) ACA test-retest reliability, and (iv) concordance of ACA- and TTM-based preferences.

RESULTS

All participants completed the TTM and 66 completed the ACA questionnaire, in 15 min on average. Outcome utilities were rank ordered in agreement with probabilities from best to worst in most participants, except for sexual dysfunction. Most participants were willing to trade survival and their most important outcome. Mean importance ratings were similar at retest. ACA- and TTM-based preferences differed. TTM-based preferences were related to past treatment, ACA-based preferences were not.

CONCLUSIONS

ACA assesses group-level preferences reliably over time and captures individual preferences independently from treatment experience in treated cancer patients. ACA seems a valid treatment outcome preference elicitation method in a context in which trade-offs between cure and quality of life need to be considered.

Evaluation of the treatment tradeoff method in rectal cancer patients: is surgery preference related to outcome utilities?

BACKGROUND

The treatment tradeoff method (TTM) has been developed specifically for decision making at the level of the individual patient. The task is tailored to the clinical decision problem at hand and may therefore be more relevant to patients than methods of outcome valuation. Despite its wide use in oncology research, few methodological studies regarding validity have been conducted.

OBJECTIVE AND METHODS

The present study evaluates the validity of the TTM in rectal cancer patients who had undergone either 1 of 2 surgery types: 1 requiring a permanent stoma (stoma group) and 1 involving a postoperative risk of fecal incontinence (no-stoma group). The authors relate the surgery preference scores to the utilities of the 2 main surgery outcome states as well as to their utility difference.

RESULTS

Surgery preference was more strongly associated with the utility difference (r > 0.54 in the total patient group) than with the utilities of the surgery outcome states per se (r < 0.44 in the total patient group). In the stoma group, surgery preference was especially related to the utility of incontinence and in the no-stoma group especially to the utility of a permanent stoma.

CONCLUSIONS

Patients indeed use their valuations of treatment outcomes states, especially those they are less familiar with, in determining their preference for one treatment over another. In clinical practice, the TTM may be used to obtain an indication of the treatment preference of an individual patient and may also be helpful to detect patients' motives to choose one treatment over another.

Review of Determinants of Patients’ Preferences for Adjuvant Therapy in Cancer

Purpose

Many studies have determined cancer patients’ preferences for adjuvant therapy, for example, by asking patients the extent of benefit they would need in order to accept the therapy. However, little is known about the determinants that influence these preferences. Our research goal was to explore which determinants underlie patients’ preferences by means of a literature review.

Methods

PubMed searches were conducted to identify studies in which cancer patients’ preferences for adjuvant therapy had been elicited by means of a treatment preference instrument. Twenty-three papers were evaluated with regard to reported relationships between preferences and potential determinants. A total of 40 determinants were recorded and classified into one of seven categories: (1) treatment-related determinants, (2) sociodemographic characteristics and current quality of life, (3) clinical characteristics, (4) measurement instrument-related determinants, (5) time-related determinants, (6) cognitive/affective determinants, and (7) specialist-related determinants.

Results

The benefit and toxicity of treatment, experience of the treatment, and having dependents (eg, children) living at home were important determinants of patients’ preferences. Furthermore, qualitative data suggested that cognitive/affective and specialist-related determinants might have a large impact on patients’ treatment preferences.

Conclusion

Our results show that patients’ preferences cannot fully be explained on the basis of treatment-related determinants and patient and clinical characteristics. More research is needed in the area of cognitive/affective and specialist-related determinants because of the lack of quantitative results. Furthermore, we recommend carrying out larger studies in which the (internal) relationships between determinants and preferences are assessed in the context of a cognitive cost-benefit model.

Patients' preferences for adjuvant chemotherapy in early-stage breast cancer: is treatment worthwhile?

When making decisions about adjuvant chemotherapy for early-stage breast cancer, costs and benefits of treatment should be carefully weighed. In this process, patients' preferences are of major importance. The objectives of the present study were: (1) to determine the minimum benefits that patients need to find chemotherapy acceptable, and (2) to explore potential preference determinants, namely: positive experience of the treatment, reconciliation with the treatment decision, and demographic variables. Preferences were elicited from patients scheduled for adjuvant chemotherapy (chemotherapy group: n = 38) before (T(1)), during (T(2)), and 1 month after chemotherapy (T(3)), and were compared to responses from patients not scheduled for chemotherapy (no-chemotherapy group: n = 38). The patients were asked, for a hypothetical situation, to indicate the minimum benefit (in terms of improved 5-year disease-free survival) to find adjuvant chemotherapy acceptable. In the chemotherapy group, the median benefit was 1% at all 3 measurement points. In the no-chemotherapy group the attitude towards chemotherapy became more negative over time, although not statistically significantly so (T(1): 12%, T(2): 15%, T(3): 15%; P = 0.10). At all measurement points, the patients in the chemotherapy group indicated that they would accept chemotherapy for significantly (P< 0.01) less benefit than the patients in the no-chemotherapy group. Of the demographic variables, age was related to preferences, but only at T(2)and only in the no-chemotherapy group. The more positive attitude towards chemotherapy and the stability of preferences in the chemotherapy group indicated that reconciliation with the treatment decision was a more important determinant of patients' preferences than positive experience of the treatment.

Patient preference for cancer therapy: an overview of measurement approaches

PURPOSE

In the era of evidence-based medicine and shared decision making, the formal assessment of patient preference for treatments or treatment outcomes has attracted much attention. In this article, the two most common approaches to the evaluation of preference, ie, utility assessment and probability trade-off assessment, are described. The purpose is to provide clinicians with the background knowledge needed to interpret preference studies published in the literature and to judge whether the reported findings are relevant to their own patients.

METHODS

An overview is given of the methods used to assess utilities and probability trade-off scores. Evidence on determinants of such scores is presented. Examples from oncology are provided. Because experience with the treatment plays an important role as a determinant of preferences for both treatments and treatment outcomes, special attention is paid to the interpretation of studies in the light of subject selection. Directions for future research are suggested.

CONCLUSION

The choice of approach and the measuring instrument depend on the goal of the preference assessment. Normal psychologic processes, such as coping, adaptation, and cognitive dissonance reduction, cause patients who are about to undergo a therapy or have experienced a therapy to rate it more favorably than other patients do. This should be remembered when using evidence from the literature to inform patients or for patient decision making.

A trial for comparing methods for eliciting treatment preferences from men with advanced prostate cancer: results from the initial visit

OBJECTIVE

The objective of this study was to evaluate the convergent validity of 3 types of utility measures: standard gamble, time tradeoff, and rating scale.

RESEARCH DESIGN

A prospective cohort of 120 men with advanced prostate cancer were first asked to rank order 8 health states, and then utility values were obtained from each participant for each of the 8 health states through 2 of the 3 techniques evaluated (standard gamble, time tradeoff and rating scale). Participants were randomly assigned to 1 of 3 possible pairs of techniques. The validity of the 3 methods, as measured by the convergence and raw score differences of the techniques, was assessed with ANOVA. The ability of the techniques to differentiate health states was determined. The inconsistencies between rankings and utility values were also measured. Proportions of illogical utility responses were assessed as the percent of times when states with more symptoms were given higher or equal utility values than states with fewer symptoms.

RESULTS

There were significant differences in raw scores between techniques, but the values were correlated across health states. Utility values were often inconsistent with the rank order of health states. In addition, utility assessment did not differentiate the health states as well as the rank order. Furthermore, utility values were often illogical in that states with more symptoms received equal or higher utility values than states with fewer symptoms.

CONCLUSIONS

Use of the utility techniques in cost-effectiveness analysis and decision making has been widely recommended. The results of this study raise serious questions as to the validity and usefulness of the measures.

Validity and interpretation of preference-based measures of health-related quality of life

Utilities are numeric measurements that reflect an individual's beliefs about the desirableness of a health condition, willingness to take risks to gain health benefits, and preferences for time. This report discusses the approaches to assess and compare the validity of methods used to assign utilities for cost-utility analysis. Threats to validity include construct underrepresentation and construct-irrelevant variance. Construct underrepresentation occurs when a stimulus presented to a judge fails to fully represent the depth and complexity of information required in actual judgments. Construct-irrelevant variation occurs when factors irrelevant to preferences influence measurements of utilities. Among several factors that cause construct-irrelevant variation are cognitive abilities, numeracy skills, emotions and prejudices, and the elicitation procedure. Commonly used elicitation methods (visual-analog scales, time tradeoff, and standard gamble) capture different facets of utilities (desirableness of states, time preferences, and risk attitude) to different degrees. The validity of an elicitation protocol depends (1) on the degree to which its scaling method captures the relevant facets of utility and (2) on the degree to which measurements are influenced by construct-irrelevant variation. Discrete-state health index models provide an alternative to direct elicitation of utilities and work by attaching fixed preference weights to observable health states. The creation of discrete-state models with current technologies requires the adoption of strong assumptions about the scaling properties of utilities. Future research must refine methods of eliciting utilities and identify sources of construct-irrelevant variability that reduce the validity of utility assessments. Because of the impact of variation in techniques on measurements, we do not recommend the combination of utilities elicited with different protocols in cost-utility analysis and do not recommend the display of cost-utility ratios from different studies in comparison or "league" tables.

Exploring health preferences in sociodemographic and health related groups through the paired comparison of the items of the Nottingham health profile

BACKGROUND

Preference weighted measures of health related quality of life are necessary for cost effectiveness calculations involving quality of life adjustment. There are conflicting data about the influence of factors such as sociodemographic and health related variables on health preferences.

STUDY OBJECTIVE

The relative values attached to the items of the Spanish version of the Nottingham Health Profile (NHP) were assessed to make comparisons across social and health subgroups.

DESIGN AND PARTICIPANTS

Preference values were obtained in sets of 250 to 253 persons (total n=1258) using the method of paired comparisons after all possible pairs of NHP items had been presented to respondents for judgement of severity. chi(2) Tests and Spearman's correlations among item ranks were calculated.

MAIN RESULTS

Findings show that preferences elicited with the method of paired comparisons are consistent and independent of the sample from which they are obtained (mean correlation coefficients across subgroups range from 0.87 to 0.96). Conclusion-The evaluation of health did not seem to be related to sociodemographic variables (gender, age, social class) or to the health status of the respondents, suggesting that health preferences are stable across different populations.

A treatment trade-off based decision aid for patients with locally advanced non-small cell lung cancer

Purpose To describe the structure and use of a decision aid for patients with locally advanced non-small cell lung cancer (LA-NSCLC) who are eligible for combined-modality treatment (CMT) or for radiotherapy alone (RT). METHODS: The aid included a structured description of the treatment options and trade-off exercises designed to help clarify the patient's values for the relevant outcomes by determining the patient's survival advantage threshold (the increase in survival conferred by CMT over RT that the patient deemed necessary for choosing CMT). Additional outcome measures included each patient's strength of treatment preference, decisional conflict, objective understanding of survival information, decisional role preference, and evaluation of the aid itself. RESULTS: Twenty-five patients met the eligibility criteria for study. Of these, seven declined the decision aid because they had a clear treatment preference (four chose CMT and three chose RT). The remaining 18 participants completed the decision aid; 16 chose CMT and two chose RT. All 18 patients wished to participate in the decision to some extent. All patients reported that using the decision support was useful to them and recommended its use for others. No patient or physician reported that the aid interfered with the physician-patient relationship. Patients' 3-year survival advantage thresholds, and their median survival advantage thresholds, were each strongly correlated with their strengths of treatment preference (rho=0.80, P < 0.001 and rho=0.77, P < 0.001, respectively). For all but one patient, either their 3-year or median survival threshold was consistent with their final treatment choice. Eight patients reported a stronger treatment preference after using the decision aid. CONCLUSIONS: We conclude that a treatment trade-off based decision aid for patients with locally advanced non-small cell lung cancer is feasible, that it demonstrates internal consistency and convergent validity, and that it is favourably evaluated by patients and their physicians. The aid seems to help patients understand the benefits and risks of treatment and to choose the treatment that is most consistent with their values.

A comparison of two approaches for assessing patient importance weights to conduct an Extended Q-TWiST analysis

OBJECTIVE

Patient-centered methods for evaluating treatments require validated preference-elicitation techniques. We describe the validation of two preference-elicitation approaches for use in an Extended Q-TWiST treatment evaluation. The first method was an "idiographic" approach, which attempts to capture intra-individual differences in the degree to which each domain distracted from and interfered with life activities. The second method, a Likert-scaled approach, asks patients to evaluate the importance of each quality-of-life (QOL) domain.

METHODS

Patient-reported QOL and preferences were assessed in participants with gastroesophageal reflux disease at baseline (n = 172), one week (n = 25), and 4 weeks after baseline (n = 100).

RESULTS

Both approaches demonstrated high internal consistency and the ability to discriminate known groups based on reported pain and number of days with symptoms. The idiographic approach exhibited responsiveness, although it was more highly correlated with QOL than the Likert-scaled approach. The Likert-scaled approach had good face validity but demonstrated low reliability compared to the idiographic approach.

CONCLUSIONS

Both preference-elicitation methods exhibited promise as well as limitations. Future research should focus on increasing the reliability of the Likert-scaled approach, reducing the overlap between the idiographic approach and QOL, and examining the relationship between reliability and responsiveness for a range of illness trajectories.

Systemic methotrexate therapy versus laparoscopic salpingostomy in tubal pregnancy. Part II. Patient preferences for systemic methotrexate

OBJECTIVE

To investigate patient preferences for systemic methotrexate therapy relative to laparoscopic salpingostomy in the treatment of tubal pregnancy.

DESIGN

Preference assessment in controlled clinical study.

SETTING

Four hospitals and one infertility clinic.

PATIENT(S)

Forty patients who had been treated for tubal pregnancy and 40 nonpregnant controls.

INTERVENTION(S)

Preference for methotrexate therapy relative to salpingostomy was established during an interview. Two scenarios were offered for methotrexate therapy: one with and one without preceding diagnostic laparoscopy. Hypothetical tubal patency rates after methotrexate therapy were varied in both scenarios until patients switched in their initial preference.

MAIN OUTCOME MEASURE(S)

Preference for systemic methotrexate therapy.

RESULT(S)

Only a few patients switched in their initial preference when the tubal patency rate after systemic methotrexate therapy was varied. Most preferred methotrexate therapy without an increase in the tubal patency rate in a scenario without preceding diagnostic laparoscopy. A small group never opted for methotrexate therapy even when it would guarantee a 100% tubal patency rate.

CONCLUSION(S)

Systemic methotrexate therapy would be preferred by most patients as part of a completely nonsurgical management strategy. Tubal patency was a decisive factor for treatment preference in a minority of patients only.

Using a treatment-tradeoff method to elicit preferences for the treatment of locally advanced non-small-cell lung cancer

The study was designed to evaluate a treatment-tradeoff method for its potential in helping lung cancer patients make treatment decisions. A treatment-tradeoff interview was conducted to determine how patients weighed potential survival benefits against the potential toxicities of different treatment options: 1) low-dose versus high-dose radiotherapy, and 2) high-dose radiotherapy versus combination chemo-radiotherapy. Fifty-six patients who had experienced cancer and 20 clinic staff participated; twenty of these participants repeated the interview in an assessment of response consistency. The treatment-tradeoff method proved feasible: all staff and 53 of the 56 patients were able to complete the process. A wide range of threshold scores across participants was observed for both tradeoffs. Sixty percent of the patients would accept the more toxic combination therapy over high-dose radiotherapy if the former offered a 10% absolute improvement in three-year survival. The method also proved reliable: test-retest correlations were high (tau ranged from 0.7 to 0.87 and r from 0.82 to 0.94) and test-retest mean score differences were low (1.3-4.2). The most clinically useful measure of consistency was a "preference consistency" index, which revealed that most patients declared the same treatment preference at test and retest. The authors conclude that, while there is great interindividual variability in willingness to accept aggressive treatments for lung cancer, patients' values can be consistently elicited with the tradeoff method. The method has potential for clinical application in decision making and for health-care policy development.

Subjective health estimations (SHE) in patients with advanced breast cancer: an adapted utility concept for clinical trials

We wished to develop and validate a simple linear analogue self-assessment (LASA) scale to assess utility values in multicentre, multicultural breast cancer trials. We compared two variants of a LASA scale (score range 0-100) with different anchoring points [perfect health to worst possible health (subjective health estimation, SHE) and perfect health to death (SHED)] in 84 patients with advanced breast cancer. Feasibility was explored in the first 48 patients interviewed. Values from the LASA scales were compared with each other and with a time trade off (TTO) interview. Scores from the two LASA scales were highly correlated (r=0.8, P < 0.0001, Spearman). The relationship between TTO interview and SHE was confirmed with tests for trend across ordered groups (linear-trend test P < 0.001). Most patients preferred SHE to SHED. SHE scores (in which high scores indicate high-health-state values) were significantly different by type of treatment, time from diagnosis and age. Thus, significantly different mean SHE scores were obtained from patients receiving no treatment or hormone therapy, mild and intensive chemotherapy (ANOVA P=0.03) and from patients with diagnosis 2 years, 2-5 years, 5-10 years and more than 10 years before interview (ANOVA P=0.02). Older patients (> 56 years) had a lower mean on the SHE scale (53 vs 61; ANOVA P=0.04). We found that the two versions of the LASA scale were equivalent for clinical purposes. SHE appeared to provide a feasible, patient-preferred and valid alternative to lengthy TTO interviews in assessing the value patients attach to their present state of health in large-scale cancer clinical trials.

Preference values for visual states in patients planning to undergo cataract surgery

To assess how preference values that cataract surgery patients assign to their preoperative visual states relate to visual acuity and problems in specific aspects of daily life, the authors interviewed 47 patients scheduled to have cataract surgery. Using a rating-scale technique with a scale from 0 (death) to 1 (excellent health), the patients had a mean preference value of 0.68 for their preoperative vision. Patients' preference values for their preoperative vision were more closely related to problems in specific aspects of daily life (especially feelings of depression and problems interacting with people) than to visual acuity in the operative eye, better eye, or worse eye, or a weighted average of visual acuities in both eyes. These results provide a rationale for relying more on patients' views about the effects of visual impairment than on measures of visual acuity when assessing the need for cataract surgery.

The use of confidence intervals for individual utilities: limits to formal decision analysis for treatment choice

This paper discusses the use of confidence intervals for utility measurements. Classic test theory is applied to estimate confidence intervals for utilities. The theory is enhanced to calculate confidence areas for combined utilities and confidence bands for the threshold line. As an example it is shown that, if confidence intervals are taken into account, the implied preferred treatment of T3-larynx carcinoma patients is uncertain for a wide range of utilities, considering the mediocre reliability of most methods of utility assessment. This implies that although utility measurement and formal decision analysis can be a useful way to look at the decision problem, ambiguity, which must be resolved by other means, will often remain.

Tradeoffs between quality and quantity of life: development of the QQ Questionnaire for Cancer Patient Attitudes

The patient's perspective is of prime concern in weighing the benefits and side effects of oncologic treatment. Little is known about patients' preference and attitudes. The authors developed a short questionnaire to assess patient attitudes concerning trade-offs between quality of life and length, or quantity, of life (the QQ Questionnaire). The questionnaire turned out to be feasible for use in various groups of cancer patients. In a factor analysis, the questionnaire was shown to consist of two factors, a Q(uality) and a L(ength) factor. Values of Cronbach's alpha for the Q and L scales (consisting of four items each) were 0.68 and 0.79, respectively. Younger patients and patients who have children assigned relatively more importance to striving for prolonged survival. Contrary to our expectation, no association was found between scores on the two scales and time tradeoff utility scores. The QQ Questionnaire can be used in research settings to study patient attitudes and the stability and determinants of patients' preferences.