Psychometric evaluation of the Health-Risk Attitude Scale (HRAS-13): assessing the reliability, dimensionality and validity in the general population and a patient population.

OBJECTIVES: The aim of this study was to assess the reliability, dimensionality and validity of the self-report questionnaire Health-Risk Attitude Scale (HRAS-13) in a sample of the general population and a patient population. METHODS: Sample 1 (n = 930) was recruited from the general population aged 18-65 years in the Netherlands. Sample 2 (n = 486) was recruited from the population of knee and hip osteoarthritis patients aged 45 and over, also from the Netherlands. Reliability was assessed using Cronbach's alpha, average inter-item correlation and item-total correlations. Dimensionality was examined using confirmatory factor analysis (CFA), principal component analysis (PCA) and bifactor analysis. Validity was assessed by performing known-group analysis using ANOVA tests. RESULTS: Cronbach's alphas of the HRAS-13 were 0.73 in sample 1 and 0.69 in sample 2. Reliability and dimensionality analyses differed slightly between the samples, and suggest that a short version of the HRAS may capture a general component of health-risk attitude. Validity assessment of known groups showed that the HRAS-13 and a likely HRAS-6 distinguished between subgroups of respondents based on most of the assessed characteristics, but not all. DISCUSSION: These findings are a preliminary indication that the HRAS-13 is a promising multidimensional instrument for measuring health-risk attitude. However, further research in various samples on decisions where health risks play a role is warranted to confirm the dimensionality of the HRAS-13 and the items to be retained in a full or a shorter version.

The construction of standard gamble utilities.

Health effects for cost-effectiveness analysis are best measured in life years, with quality of life in each life year expressed in terms of utilities. The standard gamble (SG) has been the gold standard for utility measurement. However, the biases of probability weighting, loss aversion, and scale compatibility have an inconclusive effect on SG utilities. We determined their effect on SG utilities using qualitative data to assess the reference point and the focus of attention. While thinking aloud, 45 healthy respondents provided SG utilities for six rheumatoid arthritis health states. Reference points, goals, and focuses of attention were coded. To assess the effect of scale compatibility, correlations were assessed between focus of attention and mean utility. The certain outcome served most frequently as reference point, the SG was perceived as a mixed gamble. Goals were mostly mentioned with respect to this outcome. Scale compatibility led to a significant upward bias in utilities; attention lay relatively more on the low outcome and this was positively correlated with mean utility. SG utilities should be corrected for loss aversion and probability weighting with the mixed correction formula proposed by prospect theory. Scale compatibility will likely still bias SG utilities, calling for research on a correction.

Exploring the reference point in prospect theory: gambles for length of life.

Attitude toward risk is an important factor determining patient preferences. Risk behavior has been shown to be strongly dependent on the perception of the outcome as either a gain or a loss. According to prospect theory, the reference point determines how an outcome is perceived. However, no theory on the location of the reference point exists, and for the health domain, there is no direct evidence for the location of the reference point. This article combines qualitative with quantitative data to provide evidence of the reference point in life-year certainty equivalent (CE) gambles and to explore the psychology behind the reference point. The authors argue that goals (aspirations) in life influence the reference point. While thinking aloud, 45 healthy respondents gave certainty equivalents for life-year CE gambles with long and short durations of survival. Contrary to suggestions from the literature, qualitative data argued that the offered certainty equivalent most frequently served as the reference point. Thus, respondents perceived life-year CE gambles as mixed. Framing of the question and goals set in life appeared to be important factors behind the psychology of the reference point. On the basis of the authors' quantitative and qualitative data, they argue that goals alter the perception of outcomes as described by prospect theory by influencing the reference point. This relationship is more apparent for the near future as opposed to the remote future, as goals are mostly set for the near future.

Understanding VAS valuations: qualitative data on the cognitive process.

Eliciting people's value is a central pursuit in health economics. We explored approaches to valuing a health state on a visual analog scale (VAS). Additionally, we examined whether dual processing (an interaction between automatic and controlled information processing) occurred during VAS valuation. In the first experiment, respondents were probed for their approach after valuation on a VAS. After inductive generalization, we grouped the approaches: (1) 'Sort-of ' (automatic processing), (2) 'Bisection of line first', (3) 'Numerical expression', and (4) 'Dividing into smaller segments'. In the second experiment, a short questionnaire followed the VAS in which these approaches were systematically assessed, as was awareness of the approach used, intention to re-use the approach the next time (confidence), and basis of the approach. Data showed that the 'Sort-of' approach was used most often, followed by the 'Bisection-first' approach. We argue that dual processing occurs during performance on the VAS. Awareness of the approach used was lower when an intuitive approach was used. A reasoned approach had a higher correlation with confidence. Thus, awareness of approach may improve reliability. Reducing the number of health states to be valued concurrently diminishes the complexity of the task; this may enhance the validity of the VAS.

Correcting biases in standard gamble and time tradeoff utilities.

The standard gamble (SG) method and the time tradeoff (TTO) method are commonly used to measure utilities. However, they are distorted by biases due to loss aversion, scale compatibility, utility curvature for life duration, and probability weighting. This article applies corrections for these biases and provides new data on these biases and their corrections. The SG and TTO utilities of 6 rheumatoid arthritis health states were assessed for 45 healthy respondents. Various corrections of utilities were considered. The uncorrected TTO scores and the corrected (for utility curvature) TTO scores provided similar results. This article provides arguments suggesting that the TTO scores are biased upward rather than having balanced biases. The only downward bias in TTO scores was small and probably cannot offset the upward biases. TheTTOscores are higher than the theoretically most preferred correction of the SG, the mixed correction. These findings suggest that uncorrected SG scores, which are higher than TTO scores, are too high.