Multi-center validation of Catquest-9SF visual function questionnaire in Ontario, Canada

Area of Science:

• Ophthalmology
• Health Outcomes Research
• Psychometrics

Background:

• Cataract surgery aims to improve visual function and daily task performance.
• Patient-reported outcome measures (PROMs) are crucial for evaluating the effectiveness of interventions like cataract surgery.
• The Catquest-9SF questionnaire was developed to assess visual function related to daily tasks.

Purpose of the Study:

• To evaluate the psychometric performance of the Catquest-9SF questionnaire.
• To assess the responsiveness of the Catquest-9SF to changes in visual function after cataract surgery.
• To validate the Catquest-9SF in a Canadian population undergoing cataract surgery.

Main Methods:

• A pooled analysis of prospective data from 934 patients undergoing cataract surgery in Ontario, Canada.
• Rasch analysis was used to assess psychometric properties including threshold order, precision, unidimensionality, targeting, and differential item functioning.
• Catquest-9SF scores were administered pre- and post-operatively to measure responsiveness.

Main Results:

• The Catquest-9SF demonstrated ordered response thresholds, adequate precision (person separation index = 2.01), and confirmed unidimensionality.
• One item ('satisfaction with vision') showed slight misfit (outfit = 1.51).
• A significant improvement in Catquest-9SF scores (mean 1.47 logit) was observed post-cataract surgery (p<0.001), indicating responsiveness.

Conclusions:

• The Catquest-9SF is a psychometrically sound and reliable tool for assessing visual function in cataract patients.
• The questionnaire is responsive to clinical improvements following cataract surgery in the Ontario population.
• Catquest-9SF provides valuable patient-reported data on visual function post-cataract surgery.