Variation in the readability of items within surveys

Area of Science:

• Health Services Research
• Patient-Reported Outcomes
• Health Literacy

Background:

• Health-related quality-of-life (HRQoL) surveys are essential tools in clinical research and practice.
• The National Eye Institute Visual Functioning Questionnaire-25 (VFQ-25) and the Short Form Health Survey, version 2 (SF-36v2) are widely utilized HRQoL instruments.
• Survey readability impacts patient comprehension and the validity of collected data.

Purpose of the Study:

• To assess the variability in readability of individual items within the VFQ-25 and SF-36v2 surveys.
• To determine if item readability levels align with general population reading abilities.
• To highlight the importance of item-level readability analysis in survey evaluation.

Main Methods:

• Applied Flesch-Kincaid and Flesch Reading Ease formulas to estimate readability of each survey item.
• Calculated descriptive statistics and mean readability scores for both the VFQ-25 and SF-36v2.
• Graphically represented the variation of individual item readability scores from the mean for each survey.

Main Results:

• The VFQ-25 had a mean reading grade level of 7.8 (fairly easy), while the SF-36v2 had a mean of 6.4 (easy).
• Both surveys exhibited considerable variation in item readability, with scores ranging from 3.7 to 12.0 for VFQ-25 and 2.2 to 12.0 for SF-36v2.
• Individual items presented a wide spectrum from very easy to difficult to read.

Conclusions:

• Significant variation in item readability exists within commonly used HRQoL surveys.
• Readability levels exceeding a respondent's reading ability can impede comprehension and data accuracy.
• There is a need for established standards to measure and report survey item readability.