Abstract
Purpose: :
To evaluate the reliability of the Visual Function 14-item Questionnaire (VF-14) to repeat testing by telephone after initial administration by interviewer in elderly subjects at the time of their pre-operative assessment for their cataracts.
Methods: :
A total of 42 consecutive cases awaiting cataract extraction by phacoemulsification were recruited. The main outcome measure was a composite score for the 14-item visual function questionnaire (VF-14) obtained from interviewer administered versus telephone questionnaires.Scores were converted to a 100-point scale in which 100 represents the best possible score and 0 represents the worst. Agreement between repeated assessments was investigated using the methods suggested by Bland and Altman.
Results: :
The study population comprised 21 (50%) males and 21 (50%) females having a mean (SD) age of 77 (8.0) years. The mean (SD) of aggregate VF-14 scores from interviewer administered questionnaires was 78 (21)compared to 82 (17) for the telephone questionnaires. The mean (SD) of the difference in scores, 3.4 (15) indicated no evidence of any systematic bias (p = 0.17). However, the 95% limits of agreement, - 33.6 to + 26.8, indicate poor repeatability.
Conclusions: :
Composite scores for VF-14 obtained by telephone questionnaires do not show good agreement to those obtained by interview during pre-operative assessment.