Interpretation of change scores for the National Eye Institute Visual Function Questionnaire-25: the minimally important difference

Jennifer M Burr*, David Cooper, Craig R Ramsay, Jemaima Che Hamzah, Augusto Azuara-Blanco

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


To estimate the minimally important difference (MID) in change in National Eye Institute Visual Function Questionnaire-25 (VFQ-25) composite score using methods aligned with patient perception.

Retrospective analysis of prospectively collected data from adults with primary angle closure or primary angle closure glaucoma enrolled in the Effectiveness, in Angle-closure Glaucoma, of Lens Extraction study. We included data from 335 participants with patient reported visual function (VFQ-25) and health status measured by the EQ-5D-3L over 36 months. We used the recommended anchor-based methods (receiver operating characteristic (ROC), predictive modelling and mean change) to determine the MID of the VFQ-25. EQ-5D-3L anchor change was defined as none (0.075 points).

Mean baseline VFQ-25 score was 87.6 (SD 11.8). Estimated MIDs in the change in VFQ-25 scores (95% CI) were 10.5 (1.9 to 19.2); 3.9 (-2.3 to 10.1); 5.8 (1.9 to 7.2) and 8.1 (1.7 to 14.8) for the 'within-patient', 'between-patient' change, ROC and predictive modelling anchor methods respectively. Excluding estimates from the methodologically weaker 'within-patient' method, the MID of a change in VFQ-25 composite score is 5.8 (median value).

Estimates of the MID using multiple methods assist in the interpretation of the VFQ scores. In the context of early glaucoma related visual disability, a change score of around six points on the VFQ-25 is likely to be important to patients. Further confirmatory research is required. Studies comparing changes in patient-reported outcome measure scores with a global measure of patients' perceived change are required.
Original languageEnglish
Number of pages2
JournalBritish Journal of Ophthalmology
Issue number11
Early online date18 May 2021
Publication statusPublished - 14 Nov 2022


  • Epidemiology
  • Glaucoma


Dive into the research topics of 'Interpretation of change scores for the National Eye Institute Visual Function Questionnaire-25: the minimally important difference'. Together they form a unique fingerprint.

Cite this