Abstract
Purpose: :
To evaluate the longitudinal relationships between change in best corrected distance visual acuity (BC DVA) and change in self reported visual functioning and quality of life in a dataset obtained as part of a controlled clinical trial.
Methods: :
BCVA was available in the subfoveal radiotherapy study at baseline, 6, 12 and 24 months along with data from two quality of life (QoL) instruments, the daily living tasks dependent on vision (DLTV) and the SF-36. To test the relationship between BC DVA and QoL longitudinally, an analysis of covariance (ANCOVA) was performed with QoL domain scores as the outcome variable and BC DVA in better and worse eye as covariates without reference to treatment assignment. Linear regression was performed to examine cross-sectional relationships between BC DVA and domains from the two instruments.
Results: :
Domains 1 and 2 of the DLTV exhibited the strongest relationships with BC DVA with one line of acuity loss in the better eye equating to a drop in domain scores of 2.8 and 2.6 respectively. In the SF-36 the GHP and PF domain scores dropped by 1.1 and 1.3 respectively per line of acuity loss. Effect estimates using a cross-sectional approach were twice as large as those in the longitudinal analysis with the greatest impact seen at baseline.
Conclusions: :
The results of this study indicate that adaptation may be a contributing factor to patient based responses.
Keywords: quality of life • clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • age-related macular degeneration