Implementation methods for vision related quality of life questionnaires

Abstract

AIM To determine the most reliable and consistent method and time interval over which to implement a vision impairment quality of life assessment tool.

METHODS 117 patients with low vision aged 9–101 years were assigned into three age, sex, and visual function matched groups (n = 39 in each) to answer the Low Vision Quality of Life (LVQOL) questionnaire by post, telephone, or in person. The LVQOL questionnaire was completed on four occasions, each separated by four weeks.

RESULTS Postal implementation was the most cost effective method, showed the highest internal consistency of LVQOL items, but resulted in a lower apparent quality of life score than either telephone or in-person interviews (p<0.001). There was no difference in test-retest reliability between the three methods of implementation (p = 0.12). The profile of LVQOL scores showed a trend towards reduced quality of life scores 3 months after the baseline measures, although this was not significant.

CONCLUSION Posting may be the method of choice for clinical measurement of vision related quality of life. Patients with greater visual impairment were no less likely to complete a questionnaire when implemented by post and there was no apparent bias from other people assisting them. The quality of life measure can occur at any time up to 2 months after low vision rehabilitation for the progressive nature of conditions causing low vision not to cause a decreased baseline score. The LVQOL was shown to be a highly internally consistent and reliable method for measuring quality of life in the visually impaired.