Methods for Measuring Personal Costs Associated With Vision Impairment

Abstract

Purpose: To describe and evaluate the procedures used to collect personal costs associated with vision impairment using diaries. Methods: Participants with impaired vision (VA < 6/12 or ≥ 6/12 with restricted visual fields) were recruited. Twelve-monthly diaries, provided in large print and electronic format (with audio and Braille instruction manuals and personal assistance), were used to record vision-related expenditures grouped under four categories. Two questionnaires were used to collect additional information and to test the validity of the self-reported costs. Results: Of 227 people who consented to participate, 66% (n = 150; 91 females; mean age = 64.8 years) completed ≥ 3 monthly diaries. Of the 150 eligible participants, 68% completed the diaries over 12 months, indicating a relatively high completion rate. The median total cost was AUD$2,417 per annum and median values for the four expenditure categories ranged between AUD$206 and AUD$872 per annum. The data were consistent across different months with no significant difference found between any monthly comparison (t-test; p > Bonferroni-adjusted value). Data at 1, 3, and 6 months, extrapolated to annual figures, showed no significant difference from annual total costs, indicating consistency in the data collection periods. A significant association was found between diary data and similar entries in the follow-up questionnaire, confirming the validity of the recorded expenditures (Spearman; p < 0.01). Participants commented that the diary method was useful to obtain personal costs. Conclusion: A high response rate was achieved by using diaries and additional assistance methods. The diary provided an accurate and reliable strategy to determine the major personal costs associated with vision impairment.

KEYWORDS:

• Diaries
• health economics
• healthcare costs
• visual impairment
• vision-related expenditure
• assessment methodology