Bradley, Clare

Mitchell, Jan

Royal Holloway - Pure

Results  Jan Mitchell and Clare Bradley Health Psychology Research, Department of Psychology, Royal  Holloway University of London, Egham, Surrey, TW20 0EX, UK. Measuring quality of life in macular disease: what use are utilities? Acknowledgements Our thanks go to members of the MD Society who took part in the research and to Alcon Pharmaceuticals, who funded the work  References 1 Arnold JJ and Sarks SH. Age-related macular degeneration. BMJ 2000; 321: 741-744 2 Mitchell J and Bradley C. Design of an individualised measure of the impact of macular disease on quality of life (the MacDQoL). Quality of Life Research; in press                                                                               3 Brown GC, Sharma S, Brown MM et al. Utility values and         age-related macular degeneration.  Archives of Ophthalmology 2000; 118: 47-51 4 Dolan P and Roberts J. To what extent can we explain time trade off values from other information about respondents? Social Science and Medicine 2002; 54: 919-929 Enquiries Corresponding author: Jan Mitchell PhD Research psychologist, Department of Psychology Royal Holloway, University of London Egham, Surrey, TW20 0EX, UK. E-mail: j.mitchell@rhul.ac.uk    Access to questionnaires: Clare Bradley PhD  Professor of Health Psychology Royal Holloway, University of London Egham, Surrey, TW20 0EX, UK. E-mail: c.bradley@rhul.ac.uk  Macular disease (MD): • is a chronic, degenerative, largely incurable but sometimes treatable eye condition resulting in loss of central vision needed for e.g. driving, reading, face recognition • mainly affects over 55s and is the cause of > 90% of new registrations as blind in over 65s in UK and US1  The MacDQoL2 • is an individualised measure of the impact of MD on quality of life (QoL) • has 26 domains, each with an impact score and importance rating, multiplied to give a weighted impact score. A single average weighted impact score (AWI) averages weighted impact across domains applicable to the individual respondent • has 2 QoL overview items (1 generic, 1 MD-specific) • has face validity and preliminary evidence of internal consistency reliability and construct validity2  Time trade-off (TTO) utility values: •  have been obtained for MD patients in other studies3 • factors other than condition severity may influence   utility values4 • Completion rates:  MacDQoL questionnaire = 99%,         health TTO item = 75%, vision TTO item = 71%. • Of those completing TTO items, percentages giving a utility value of 1 (U = 1, usually interpreted as indicating optimal vision) were: vision TTO = 38%, health TTO = 42% • U = 1 distributed equally between blind, partially sighted and not registered groups  Methods • Lower TTO completion rates suggest reduced face validity and less acceptability of TTO questions. • TTO questions less sensitive to subgroup differences than MacDQoL (AWI) and MD-specific overview item. • Frequency and distribution of U = 1 and comments about TTO questions indicate that people may not be willing to co-operate with TTO utilities methodology and, when they are, their responses do not provide a measure of QoL. Conclusions Participants: • 171 recruited from the MD Society (UK) self-help groups (mean age 79 yrs, 77% women; registered blind n = 51, registered partially sighted n = 60,         not registered n = 60) • if able to read, randomised to complete MacDQoL, TTO questions and SF-36 item by telephone interview or self-completion • if unable to read had short telephone interview, completing MacDQoL overview items, TTO questions and SF-36 item • Vision-specific and health-specific TTO utility values were compared with: MacDQoL AWI, generic overview,  MD-specific overview and SF-36 items • Spearman’s correlations (Table 1) indicated: ⇒ TTO questions were not correlated with registration status, health status or MacDQoL variables ⇒ MacDQoL AWI and MD-specific overview item were       associated with registration status • Comments about TTO questions (Figure 1) recorded during phone interviewing indicated:  ⇒ questions difficult to answer ⇒ people considered things other than their own QoL when answering the questions   How many more years do you expect How do I know….?   I could be dead by tonight! Figure 1. Reactions to TTO questions What is the maximum number of hears, if any, would you be willing to give up if you could have this treatment and have perfect vision for your remaining years? At 50 or 60 it would be different. At my time of life it’s not worth considering. Better to be around for the family even though incapacitated. Only god knows the answer to this. I’m blessed with a wonderful partner. As long as we’re together | would not give up any time for perfect vision. If I was on my own I might think differently Nonsense and hypothetical question. I’m amazed at an academic institution coming up with such a ridiculous question!  General health Health TTO Vision TTO MD-specific QoL Generic QoL Registra-tion status MacDQoL AWI  0.089 0.065 0.098 0.639* 0.298* 0.444* Registra-tion status -0.18 0.099 0.033 0.426* 0.004  Generic QoL 0.561* 0.15 0.1 0.069   MD-specific QoL -0.105 0.020 0.117    Vision TTO 0.054 0.731*     Health TTO 0.172      Table 1. Correlations between outcome measures * significant at p < 0.01 

Measuring quality of life in macular disease: what use are utilities? [Abstract 1188]

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Measuring quality of life in macular disease: what use are utilities? [Abstract 1188]

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