The MacDQOL Individualized Measure of the Impact of Macular Disease on Quality of Life

Abstract:

The MacDQOL is an individualized measure of the impact of macular disease (MD) on quality of life. It was designed with reference to people who had MD, using focus groups, and to the literature. An early draft was pilot tested with a postal study in which participants (N = 65) were recruited from the membership of the UK Macular Disease Society. This study showed significant differences in MacDQOL scores between people who were not registered and those who were registered blind (p < 0.001) or partially sighted (p < 0.001) and the findings offered early evidence of construct validity.

There followed a longitudinal study (N = 156) to enable further validation of the MacDQOL. Participants were recruited from an ophthalmic specialist’s patient list. Principal components analysis revealed a single scale with excellent internal consistency reliability (Cronbach’s alpha = 0.946). Test-retest reliability was excellent with MacDQOL scores at time 1 and time 2 highly correlated (r = 0.946) and no differences in scores between time 1 and time 2 (p = 0.85). Construct validity was demonstrated by the MacDQOL’s sensitivity to several measures of vision (near and distance visual acuity, contrast sensitivity, reading speed, color recognition). There was some correlational evidence of responsiveness to change in vision over time.

Good response rates and completion rates indicated that the MacDQOL is acceptable to participants and does not impose too great a burden.

The MacDQOL has been used in clinical trials and a number of other studies. Evidence to date indicates that MD has a negative impact on the quality of life of people with the condition and that the negative impact increases with increasing severity of MD. The MacDQOL promises to be a valuable tool in the investigation of changes in patients’ quality of life in clinical trials of medical treatments and rehabilitative interventions.