The MacDQoL individualized measure of the impact of macular degeneration on quality of life: reliability and responsiveness.
OBJECTIVE
To investigate the MacDQoL test-retest reliability and sensitivity to change in vision over a period of one year in a sample of patients with age-related macular degeneration (AMD).


METHODS
A prospective, observational study.


METHODS
Patients with AMD from an ophthalmologist's list (n = 135) completed the MacDQoL questionnaire by telephone interview and underwent a vision assessment on two occasions, one year apart.


RESULTS
Among participants whose vision was stable over one year (n = 87), MacDQoL scores at baseline and follow-up were highly correlated (r = 0.95; P < .0001). Twelve of the 22 scale items had intraclass correlations of >.80; only two were correlated <.7. There was no difference between baseline and follow-up scores (P = .85), indicating excellent test-retest reliability. Poorer quality of life (QoL) at follow-up, measured by the MacDQoL present QoL overview item, was associated with deterioration in both the better eye and binocular distance visual acuity [VA] (r = 0.29; P = .001, r = 0.21; P = .016, respectively; n = 135). There was a positive correlation between deterioration in the MacDQoL average weighted impact score and deterioration in both binocular near VA and reading speed (r = 0.20; P = .019, r = 0.18; P = .041, respectively; n = 135).


CONCLUSIONS
The MacDQoL has excellent test-retest reliability. Its sensitivity to change in vision status was demonstrated in correlational analyses. The measure indicates that the negative impact of AMD on QoL increases with increasing severity of visual impairment.
Department of Psychology, Royal Holloway, University of London, Egham, Surrey, United Kingdom. j.mitchell@rhul.ac.uk
Jan
J
Mitchell
James
J
Wolffsohn
Alison
A
Woodcock
Stephen J
SJ
Anderson
Timothy
T
Ffytche
Martin
M
Rubinstein
Winfried
W
Amoaku
Clare
C
Bradley
D000368:Aged; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000503:physiopathology / Q000523:psychology*; D008297:Male; D011446:Prospective Studies; D011594:Psychometrics / Q000295:instrumentation*; D011788:Quality of Life; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D018434:Sickness Impact Profile; D011795:Surveys and Questionnaires; D015348:Vision, Binocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology