Development of cataract-specific item pool to measure patient-reported outcomes

Abstract

Objective Based on the principles of evidence-based medicine, the present study aimed to develop a cataract-specific item pool for the assessment of quality of life (QoL) in ophthalmic patients and the efficacy of specific therapy. Methods The item pool for patient reported outcomes (PROs) of cataract was established based on the guideline of the international PROs development process. Databases including PubMed, Embase, CNKI, WanFang Data, VIP, CBM were thoroughly searched. The items pool of PROs was established using the following steps: Confirm conceptual framework, identify extant items in cataract-specific instruments and the qualitative literature, select items and cross-cultural adaptation, focus groups and semi-structured interviews, item classification and selection, identify items stem and response options, expert review and revision of items, cognitive interviews and develop final version of instrument. Results The conceptual framework of item pool consists of vision-related activity limitation (VRAL) domain, vision symptoms domain and emotional well-being domain. After manual scanning for cataract-specific instruments, 19 questionnaires were extracted for the initial item pool development. After the original identification of items, focus groups and semi-structured interviews, item classification and selection, expert review and cognitive interviews, the number of items were 249, 204, 118 and 94, respectively. After cognitive interviews, all items were sorted into VRAL domain, vision symptoms domain and emotional well-being domain, which contained 41, 28 and 25 items, respectively. Total items utilized four response options. Conclusion Based on the principles of evidence-based medicine for PROs, the final item pool contained majority of the items under VRAL, vision symptoms and emotional well-being domains. Consequently, the language of items under each domain was simplified for interpretation by the patients, and possessed perfect content validity. This cataract-specific item pool has corrected the defects of PROs instruments in ophthalmology, and provided a formal reference for establishing item pools. Key words: Evidence-based medicine; Cataract; Patient reported outcomes; Item pool