Catquest-9SF questionnaire and eCAPS: Validation in a Canadian population

Area of Science:

• Ophthalmology
• Health Services Research
• Psychometrics

Background:

• Visual acuity alone is insufficient for prioritizing cataract surgery.
• Patient-reported outcome measures (PROMs) like Catquest-9SF and eCAPS assess visual function related to daily tasks.
• Validation of these tools in diverse populations is crucial for clinical applicability.

Purpose of the Study:

• To validate the Catquest-9SF questionnaire and the electronic cataract appropriateness and priority system (eCAPS) in a Canadian population.
• To develop shorter versions of Catquest-9SF and eCAPS for enhanced clinical utility.
• To assess the psychometric properties of both instruments using Rasch analysis.

Main Methods:

• The English versions of Catquest-9SF and eCAPS were administered to pre-operative cataract patients in Ontario, Canada.
• Rasch analysis was employed to evaluate category threshold order, item fit, unidimensionality, precision, targeting, and differential item functioning.
• 313 patients completed both self-administered questionnaires.

Main Results:

• Catquest-9SF demonstrated favorable psychometric properties, including ordered response thresholds, adequate precision (PSI=2.09, reliability=0.81), and unidimensionality.
• eCAPS exhibited inadequate precision (PSI=0.19, reliability=0.04) and required exclusion of 3 items due to misfit with the Rasch model.
• A significant proportion of participants (78.8%) scored low on eCAPS, indicating potential ceiling effects.

Conclusions:

• The Catquest-9SF is validated for assessing visual function in Canadian patients seeking cataract surgery.
• eCAPS demonstrated limitations in differentiating patients with impaired visual function and requires further refinement.
• Mistargeting in Catquest-9SF suggests tasks were relatively easy, aligning with prior research.