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J.E. Keeffe, R. Misajon, S. Peacock, G. Hawthorne, A. Iezzi, J. Richardson; Estimation of Vision–Related Disutility Values Using VisQoL . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1966.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To examine the disutility values in the first stage of the modelling of VisQoL (Vision & Quality of Life Index), a vision–related utility measure. To develop VisQoL–II based upon the generic health–related utility instrument AQoL–II (Assessment of Quality of Life – Mark 2) that incorporates VisQoL to increase sensitivity to vision–related quality of life. The goal is to demonstrate that VisQoL is a suitable tool for the economic evaluation of eye care and rehabilitation programs. Methods: Participants were recruited for Time–trade–off (TTO) interviews. Adults with a vision impairment (VA in better eye <20/30) were recruited from eye clinics and vision–related services. Participants were also recruited from the general community. Recruitment was based on place of residence to represent the various socioeconomic levels within Melbourne metropolitan community. The TTO interview consisted of the 6 items from VisQoL and 6 dimensions from AQoL–II (i.e. senses, pain, mental well–being, independent living, family and social well–being, and coping). Positive and negative utilities were converted into disutilities, where 0.00 and 1.00 represent best health and death respectively, and values above 1.00 represents ‘worse than death’ health states. Disutilities were then estimated from the TTO data using a multiplicative model. Results: TTO interviews were conducted with 366 participants; 162 adults with a vision impairment and 166 from the general community. Item disutilities were greatest for the items measuring the impact of vision on the ability to cope with life demands, ability to fulfil roles and to have friendships (.37, .33 and .31 respectively on a best–worst vision health state scale). The item scores for organising assistance, confidence to join in activities, and likelihood of injury were .30, .28 and .27 respectively. The VisQoL all–worst health state disutility of 0.87 (on a life–death scale) was higher than the scores determined previously for all six dimensions of AQoL–II. The VisQoL–II (VisQoL + AQoL–II dimensions) all–worst health state disutility was 1.12 (worse than death), which is similar to the previous disutility found for AQoL–II all–worst health state. Conclusions: Vision has an important impact on quality of life. Although further modelling is required, VisQoL and VisQoL–II will provide a vision–specific utility measure for the economic evaluation vision–related programs and services.
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