Catquest-9SF questionnaire: validation of the Portuguese version using the Rasch analysis

Area of Science:

• Ophthalmology
• Health Sciences
• Psychometrics

Background:

• Cataract surgery is a common procedure aimed at restoring vision.
• Patient-reported outcome measures (PROMs) are crucial for evaluating the effectiveness of interventions.
• The Catquest-9SF is a widely used questionnaire for assessing visual functioning.

Purpose of the Study:

• To validate the Portuguese version of the Catquest-9SF questionnaire.
• To assess its applicability in a Brazilian population with cataracts.
• To determine the correlation between questionnaire scores and preoperative visual acuity.

Main Methods:

• Translation and back-translation of the Catquest-9SF into Portuguese.
• Prospective study involving 120 Brazilian patients awaiting cataract surgery.
• Rasch analysis to evaluate psychometric properties and item response theory.

Main Results:

• The Portuguese Catquest-9SF demonstrated acceptable item fit, unidimensionality, and good category organization.
• Adequate person separation index (3.07) and absence of differential item functioning were observed.
• A statistically significant correlation was found between visual acuity (logMAR) and the Catquest-9SF logit score (r=0.282, p=0.004).

Conclusions:

• The Portuguese version of Catquest-9SF is valid, reliable, and culturally appropriate for Brazilian patients.
• The questionnaire is easy to use and effectively estimates subjective visual functioning in cataract patients.
• A significant correlation between visual acuity and questionnaire scores supports its clinical utility.