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The impact of patients' subjective life expectancy on time trade-off valuations
Linköping University, Department of Medical and Health Sciences, Health Technology Assessment and Health Economics. Linköping University, Faculty of Health Sciences.
Department of Health Policy and Management, Erasmus University, Rotterdam.
Linköping University, Department of Medical and Health Sciences, Health Technology Assessment and Health Economics. Linköping University, Faculty of Health Sciences.
2013 (English)In: Medical decision making, ISSN 0272-989X, E-ISSN 0112-0006, Vol. 33, no 2, 261-270 p.Article in journal (Refereed) Published
Abstract [en]

Background. Quality-adjusted life-year (QALY) calculations in economic evaluations are typically based on general public or patient health state valuations elicited with the time tradeoff method (TTO). Such health state valuations elicited among the general public have been shown to be affected by respondents subjective life expectancy (SLE). This suggests that TTO exercises based on time frames other than SLE may lead to biased estimates. It has not yet been investigated whether SLE also affects patient valuations. Objective. To empirically investigate whether patients SLE affects TTO valuations of their current health state. Methods. Patients with different severities of diabetic retinopathy were asked in a telephone interview to value their own health status using TTO. The TTO time frame (t) presented was based on age- and sex-dependent actuarial life expectancy. Patients were then asked to state their SLE. Simple and multiple regression techniques were used to assess the effect of the patients SLE on their TTO responses. Results. In total, 145 patients completed the telephone interview. Patients TTO values were significantly influenced by their SLE. The TTO value decreased linearly with every additional year of difference between t and the patients SLE; that is, patients were more willing to give up years the shorter their SLE compared with t. Conclusion. Patients SLE influenced their TTO valuations, suggesting that respondents SLE may be the most appropriate time frame to use in TTO exercises in patients. The use of other time periods may bias the TTO valuations, as the respondents may experience the presented time frame as a gain or a loss. The effect seems to be larger in patient valuations than in general public valuations.

Place, publisher, year, edition, pages
SAGE Publications (UK and US) , 2013. Vol. 33, no 2, 261-270 p.
Keyword [en]
utility measurement, preferences and quality of life, health state preferences, utilities, valuations, utility inconsistencies, time tradeoff, quality adjusted life year weights, QALYs
National Category
Medical and Health Sciences
URN: urn:nbn:se:liu:diva-76282DOI: 10.1177/0272989X12465673ISI: 000316684200014OAI: diva2:513380

Funding Agencies|Astra Zeneca AB Sweden||Ostergotland County Council||

Available from: 2012-04-02 Created: 2012-04-02 Last updated: 2013-05-06Bibliographically approved
In thesis
1. Health economic aspects of diabetic retinopathy
Open this publication in new window or tab >>Health economic aspects of diabetic retinopathy
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

To ensure that the resources of the health care sector are used effectively, new technologies need to be evaluated before implementation to examine if they generate health outcomes at an acceptable cost. This information can be collected by performing health economic evaluations in which the costs and health outcomes of different technologies are compared. To estimate the effect on health care budgets, there is also a need for information about the prevalence of the specific disease. Health outcomes in health economic evaluations are often measured in quality-adjusted life years (QALYs), which are calculated by multiplying the remaining life years after an intervention by a weight representing the health-related quality of life (HRQoL) during those years.

This thesis aims to provide deeper knowledge of the health economic aspects of diabetic retinopathy (DR), an eye complication that affects patients with diabetes and may in the worst case lead to blindness. The focus is on three empirical and two methodological health economic research questions. The empirical research areas cover prevalence, costs, and HRQoL related to patients with DR. The methodological research questions explore the performance of different methods for estimation of QALY weights. This is of interest since it has been argued that the most common methods for estimating QALY weights may not capture all relevant vision-related aspects of quality of life. The analyses comprehend the validity of different methods for estimating QALY weights among patients with DR and if the results of one of the specific methods for estimating QALY weights, the time trade-off (TTO) exercise, are affected by patients’ subjective life expectancy (SLE).

The empirical results demonstrate that DR is seen in approximately 40% and 30% of patients with type I and type II diabetes respectively, indicating that the prevalence of DR has decreased in both of these patient groups. Healthcare costs vary considerably between different severity levels of the disease, being estimated at €26, €257, €216, and €433 per patient per year for background retinopathy, proliferative diabetic retinopathy (PDR), diabetic macular oedema (DMO), and PDR combined with DMO respectively. Blindness due to DR is associated with an increased use of transportation services, caregiving services, and assistive technologies as well as productivity losses. This suggests that preventing the progression of DR may lower healthcare costs. Patients with vision impairment due to DR have lowered HRQoL in various dimensions, but the diagnosis of DR in itself has only a limited effect on HRQoL.

The results on the methodological research questions show that different methods for estimating QALY weights seem to give different results. In comparison to EQ-5D, the Health Utilities Index Mark 3 (HUI-3) is the most sensitive method for detecting differences in QALY weights due to DR, and if decisions are to be made based on values from the general public, it can be recommended for use in cost-utility analyses of interventions directed at DR. Neither of the direct methods, TTO and the visual analogue scale, seems to be sensitive to differences in visual function, and more research is needed concerning the role of vision in people’s responses to the TTO exercises. In TTO exercises with time frames based on actuarial life expectancy, the patients’ SLE has an effect on their willingness to trade off years for full health. Thus, applying time frames deviating from patients’ SLE may result in biased QALY weights. Such bias may appear stronger within patient populations than within the general public.

In conclusion, this thesis offers estimates for prevalence, costs, and QALY weights that can be used in economic evaluations of interventions directed at DR and as benchmarks for future DR research in order to follow up consequences of changes in diabetes care. In addition, it demonstrates that the choice of method for estimating QALY weights may have an impact on whether an intervention is considered cost-effective.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2012. 137 p.
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1293
diabetes, diabetic retinopathy, health economic evaluations, quality-adjusted life years, costs, quality of life, prevalence
National Category
Health Care Service and Management, Health Policy and Services and Health Economy
urn:nbn:se:liu:diva-76283 (URN)978-91-7519-964-1 (ISBN)
Public defence
2012-05-04, Eken, Entrance 65, Campus US, Linköping University, Linköping, 09:00 (English)
Available from: 2012-04-03 Created: 2012-04-02 Last updated: 2012-04-12Bibliographically approved

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