Comparison of preferences for health outcomes in schizophrenia among stakeholder groups

Abstract

Background: To determine the effectiveness of psychiatric interventions for use in cost-effectiveness analysis, we assessed the feasibility of using a multimedia computer survey to study preferences (utilities) for health outcomes among persons with schizophrenia, family members of persons with schizophrenia, health professionals, and the public.

Methods: We developed videos depicting two patterns of mental health impairment in schizophrenia, both with and without pseudo-parkinsonism side-effects. These descriptions were integrated into a computer program that measured preferences using two psychometric methods: (1) standard gamble and (2) a visual analog scale. This program was used to compare preferences among potential stakeholder groups.

Results: 20 persons with schizophrenia, 11 family members, 20 healthy volunteers and 14 health professionals participated in the computerized interview. All but one subject completed the survey. The correlation among ratings of various states was high (r=0.7–0.95) and ratings were internally consistent in 89% of participants. There were significant differences in values between groups for health states (p=0.024) and in values for the effects of pseudo-parkinsonism on quality of life (p<0.001). Persons with schizophrenia valued the disease states more highly and placed more significance than did other groups on the effects of pseudo-parkinsonism on quality of life.

Conclusions: Computer-based multimedia techniques can offer a feasible and valid approach to measure preferences for outcomes in schizophrenia. The study found significant differences in preferences among stakeholder groups for schizophrenia outcomes. Further work is needed to clarify how these differences affect clinical decision-making and policies for health resource allocation.

Introduction

As health care dollars tighten, there is more interest in the determination of the effectiveness of psychiatric interventions. Assessments of the efficacy of anti-psychotic drugs have typically been performed using symptom rating scales (Overall and Gorham, 1962, Kay et al., 1987, Andreasen and Olsen, 1982) where scores are based on the number and degree of symptoms. However, these types of measurements are disease specific and do not lend themselves to use in cost-effectiveness analysis, a discipline that has become an important evaluative tool in a climate where new pharmacological therapies for diseases such as schizophrenia, appear to treat a wider range of disease symptoms and have fewer side effects (Davis and Janicak, 1996, Sanger, 1997, Beasley et al., 1997), but at considerably higher costs than conventional agents.

Given the increasing cost constraints in the medical environment, the question of whether the health benefits of the newer anti-psychotic drugs are a good value relative to other opportunities for improving the collective health of persons with schizophrenia has become crucial. The issue of whether an intervention constitutes a good health-dollar value is the focus of the discipline of cost-effectiveness analysis (Fuchs and Garber, 1990, Weinstein and Stason, 1977). One method of evaluating outcomes for use in cost-effectiveness analysis is by comparing preferences for health states generated by an intervention, to preferences for health states from no intervention. In other words, cost-effectiveness analyses are not driven by the presence or degree of health abnormality, but by the significance of the abnormality to the global mental and physical well-being of the individual. Numerical judgments of the significance of health impairments are called “preferences,” “values,” or “utilities.” In this paper, we will use the term preferences to refer to the generic concept of weights. This study is a step toward obtaining value weights for use in cost-effectiveness analyses of treatments for schizophrenia.

However, measuring perceptions of the significance of a health abnormality is nontrivial. Preferences for levels of health are measured using various psychometric techniques. The most common method is the double-anchored visual analog scale. Typically the top anchor of the scale is “perfect health,” the bottom anchor is “death,” and the preference rating for the state is the scaled distance between the two anchors (Gold et al., 1996). Another approach, known as the Standard Gamble method, scales the desirability of the health outcome in terms of the maximum risk of death the individual would accept, to not live with the health outcome (Bennett and Torrance, 1996, von Neumann and Morgenstern, 1947). One way to think of the standard gamble is as an opportunity to undergo a hypothetical therapy that would yield perfect health after the treatment is complete. In the gamble, a subject determines the maximum risk of death, he or she might be willing to accept as part of such a treatment. The utility of the state is (approximately) 1.0 minus the maximum acceptable risk of death for the treatment. The Standard Gamble is considered the reference method for measurement of preferences for use in cost-effectiveness analysis (von Neumann and Morgenstern, 1947). Only a few studies have applied the Standard Gamble to measure values for health outcomes in schizophrenia or related areas (Lenert et al., 1997, Morss et al., 1993, Revicki et al., 1996, Chouinard and Albright, 1997).

Another obstacle inhibiting studies of values for health outcomes in schizophrenia has been the difficulty of describing the effects of schizophrenia to persons who are naive to this disorder. This difficulty has largely precluded elicitation of preferences from the general public. In addition, the complexity of the value assignment task has also limited the participation of persons with schizophrenia. It has also hindered comparative studies aimed at understanding the differences in the perceived value of novel anti-psychotics among other stakeholders groups, such as health professionals and family members of persons with schizophrenia. If patients cannot participate in preference studies, due to cognitive impairments related to their disorder, family members and health professionals are two potential groups that could act as proxy’s for patients in preference studies. However, little data exists on the similarity or differences in preferences between patients, family members and health professionals for health outcomes in schizophrenia. The only published study examining this issue, conducted in the United Kingdom, found similarities in preferences (Revicki et al., 1996).

To address these issues, we developed a multimedia computer instrument that depicts how schizophrenia can affect lives. These depictions, in turn, permit us to assess the feasibility of using this computer survey to obtain preferences (utilities) for health outcomes in schizophrenia among: (1) persons with schizophrenia; (2) family members of persons with schizophrenia; (3) health care providers; and (4) the public. We hypothesized that the health values of these groups differed and that the choice of group in which to perform measurements might affect the results of cost-effectiveness analyses for treatments of schizophrenia. In this study, we conducted a preliminary assessment of this hypothesis.