Patient-reported outcomes (PRO's) in glaucoma : a systematic review

The aim of this review was to summarize literature in view of patient-reported outcome (PRO) instruments for glaucoma and provide guidance on how outcomes are best assessed based on evidence about their content and validity. A systematic literature review was performed on papers describing the developmental process and/or psychometric properties of glaucoma or vision-specific PRO-instruments. Each of them was assessed on their adherence to a framework of quality criteria. Fifty-three articles were identified addressing 27 PRO-instruments. In all, 18 PRO's were developed for glaucoma and 9 for diverse ophthalmologic conditions. Seven instruments addressed functional status, 11 instruments quality of life and 9 instruments disease and treatment-related factors. Most of the instruments demonstrated only partially adherence to predefined quality standards. The tools for assessing functional status were of poor quality, while the Glaucoma Quality of Life Questionnaire and the Vision Quality of Life Index were well-developed QoL measures, yet only validated using classical techniques. The Rasch-scaled QoL-tools, IVI and VCM1 need to improve their item-content for glaucoma patients. The questionnaires to measure adherence should improve their validity and the Treatment Satisfaction Survey for Intra Ocular Pressure pops out as the highest quality tool for measuring topical treatment side effects. This review revealed that most PRO-instruments demonstrated poor developmental quality, more specifically a lack of conceptual framework and item generation strategies not involving the patients' perspective. Psychometric characteristics were mostly tested using classical validation techniques.