Purpose: To develop and assess the psychometric properties of a quality of life (QoL) assessment tool for Chinese patients treated with intravitreal injection (IVI) of anti-vascular endothelial growth factor (anti-VEGF).
Methods: We developed a 31-item IVI-QoL questionnaire using semi- structured patient interviews and expert panel consultation, drawing on a study of the literature. After pretesting on a subset of patients undergoing IVI, the questionnaire was pared down to 23 items. In total, 364 completed questionnaires were received. The IVI-QoL was further developed and evaluated using Rasch analysis.
Results: The final IVI-QoL version was constructed with 23 items in four dimensions: visual function, emotional subscale, social function, and healthy behavior, based on item reduction and exploratory factor analysis. The person separation indices for the four subscales ranged from 2.05 to 2.60. No items had a differential item functioning (DIF) contrast greater than 0.5 logits. The IVI-QoL-23 scale showed satisfactory internal consistency (Cronbach's alpha > 0.9).
Conclusions: The IVI-QoL-23 is reliable and valid for evaluating the QoL of Chinese patients treated with intravitreal injection of anti-VEGF drugs.