[Creating a specific quality-of-life questionnaire in patients with glaucoma: item generation]

Abstract

The methods for developing Health-Related Quality-of-Life (HRQoL) measures and their application in medical research have demonstrated their utility in various chronic, progressive, or life-threatening diseases. The efforts made to allow the patient's perspective to be included in the methodological framework of evidence-based medicine have been successful. The assumption of a strong relationship between clinical status and daily life is certainly valid in ophthalmology. However, there is a lack of specific HRQoL measures dedicated to ophthalmic diseases. Our work aimed at creating the first Glaucoma-specific Quality of Life scale - the Glau-QoL questionnaire - to provide researchers and physicians with a comprehensive, practical, and validated tool. This article describes the first stage of the process, which consisted in generating items and formatting them in order to create a questionnaire that exhaustively covers the relevant concepts. The whole process was conducted by an expert committee including clinicians and methodologists. The standard recommendations in the development of a HRQoL questionnaire were followed: we first identified existing tools and performed a preliminary collection of concepts from the published literature; we then designed an interview guide with the help of clinicians; a trained psychologist interviewed 22 patients at various disease severity stages (from isolated hypertonic to severely impaired); the interviews were tape-recorded and scripted; general domains and related detailed concepts were identified from the script; they were then analyzed and organized; the format of the questionnaire was set up; and questions were derived from the patient's verbatim to capture the identified detailed concepts. The test questionnaire was applied to seven patients for cognitive debriefing. We finally amended the test questionnaire and designed the pilot questionnaire according to the patients' tests and the clinician's review. The test questionnaire was well accepted by the patients, despite a completion duration ranging from 14 to 35 minutes. The pilot questionnaire contained 151 items, grouped into 5 sections: (1) vision problems, physicians, and daily treatment (49 items); (2) activities of daily living (37 items); (3) self-expression (37 items); (4) vision problems and mood (14 items); and (5) other questions (14 items). The next step of our work will be the item reduction process and the psychometric validation of the Glau-QoL questionnaire.