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Quality of life and relative importance: a comparison of time trade-off and conjoint analysis methods in patients with age-related macular degeneration
  1. P A Aspinall1,
  2. A R Hill1,
  3. B Dhillon1,
  4. A M Armbrecht1,
  5. P Nelson2,
  6. C Lumsden2,
  7. E Farini-Hudson2,
  8. R Brice3,
  9. A Vickers3,
  10. P Buchholz3,4
  1. 1Princess Alexandra Eye Pavilion, Edinburgh, UK
  2. 2Visual Impairment Research Group, School of the Built Environment, Heriot-Watt University, Edinburgh, UK
  3. 3Adelphi Research Group, Bollington, Cheshire, UK
  4. 4Allergan Europe, Pforzheimersts, Ettlingen, Germany
  1. Correspondence to: Professor P A Aspinall Heriot-Watt University, Riccarton, Edinburgh EH14 3AZ, Scotland, UK; p.a.aspinall{at}


Aim: To investigate the relative priorities in quality of life (QoL) in patients with age-related macular degeneration (AMD).

Methods: Measures of visual function, QoL and utility associated with visual loss were obtained from 122 patients with AMD classified according to macular morphology. The two methods of utility assessment were time trade-off (TTO) and conjoint analysis (CA), which have been recommended by the UK’s National Institute of Clinical Excellence as techniques for the assessment of healthcare priorities.

Results: Results show that the two methods for assessing utility are poorly related: TTO relates moderately to visual function and disease severity but CA does not. CA identified two different subgroups of patients: one with outdoor mobility and the other with reading as their main priority.

Conclusion: Further work is needed and caution required in interpreting data obtained using these methodologies for determining their relative importance in vision-related QoL studies.

  • AMD, age-related macular degeneration
  • ANOVA, analysis of variance
  • CA, conjoint analysis
  • logMAR, logarithm of the minimum angle of resolution
  • QoL, quality of life
  • TTO, time trade-off
  • VA, visual acuity

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  • i The five attributes of daily living were identified from previous studies as being relatively independent (see appendix). These were: “difficulty reading or seeing fine detail”, “difficulty pouring liquids and performing household chores”, “difficulty with glare from bright lights”, “difficulty getting about outside the house alone” and “difficulty recognising faces”. The first two attributes in the preceding list were excluded from the three-attribute version for patients with poorer visual acuity who were unable to read 36-point print. Three levels of difficulty were used to describe each attribute (ie, “no difficulties”, “a few difficulties” and “a lot of difficulties”).

  • Published Online First 17 January 2007

  • Competing interests: None.