Evaluation of minimum clinically meaningful changes in scores on the National Eye Institute Visual Function Questionnaire (NEI-VFQ) SST report number 19

Päivi H. Miskala, Joan L. Jefferys, Carol M. Mangione, Eric B. Bass, Neil M. Bressler, Marta M. Gilson, Ashley L. Mann, Cynthia A. Toth, Barbara S. Hawkins

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To evaluate responsiveness of the National Eye Institute Visual Function Questionnaire (NEI-VFQ) to changes in visual acuity and to provide estimates of minimum clinically meaningful changes in NEI-VFQ scores. Methods: Data were combined from three clinical trials of submacular surgery for subfoveal choroidal neovascularization. Patients who completed NEI-VFQ interviews and visual acuity measurements at baseline and 2 years later contributed data for analysis. Data were analyzed using anchor-based (relating 2-year change in NEI-VFQ to 2-year change in visual acuity using correlation and linear regression) and distribution-based (standardized response mean) methods. Results: Of 1,015 patients enrolled, 828 patients completed NEI-VFQ interviews and had visual acuity measurements at baseline and 2 years later. Median age of patients was 75 years (range 18 to 94); all patients had subfoveal choroidal neovascularization in at least one eye. Median overall NEI-VFQ score at baseline was 69.9 (mean, 66.5). Based on anchor-based methods, a 2-line change in visual acuity of the better-seeing eye translated to a 3.4-point change in the overall NEI-VFQ score and from 2.4-point to 7.0-point changes in most subscale scores. The NEI-VFQ was sensitive to both gains and losses in visual acuity; the standardized response mean for the overall NEI-VFQ score in patients with a 2-line gain was 0.6 and for patients with 2-line loss was -0.3. In the subgroup of patients with a 2-line loss of visual acuity in the better-seeing eye, patients who had overall NEI-VFQ scores at baseline greater than the median (59.8) had an standardized response mean of -0.9 for the overall NEI-VFQ score and patients who had overall NEI-VFQ scores at baseline at or below the median had a standardized response mean of 0.2 for the overall NEI-VFQ score. A 4-point change in the overall NEI-VFQ and a 5-point change in individual subscale scores corresponded to a small clinically meaningful change. Conclusions: The NEI-VFQ was responsive to 2-year changes in visual acuity but was less responsive to changes among patients with poorer NEI-VFQ scores at baseline. Based on this analysis, a 4-point change in the overall NEI-VFQ and a 5-point change in individual subscale scores may be considered minimum clinically meaningful within-person changes in NEI-VFQ scores.

Original languageEnglish (US)
Pages (from-to)205-215
Number of pages11
JournalOphthalmic Epidemiology
Volume14
Issue number4
DOIs
StatePublished - Jul 2007
Externally publishedYes

Keywords

  • Anchor-based
  • Distribution-based
  • Responsiveness

ASJC Scopus subject areas

  • Epidemiology
  • Ophthalmology

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