Patient-reported outcomes (PROs) in glaucoma: a systematic review

Methodological quality of the review: Medium confidence

Author: Vandenbroeck S, De Geest S, Zeyen T, Stalmans I, Dobbels F

Geographical coverage: Not reported

Sector: Glaucoma

Sub-sector: Patient-reported outcomes

Equity focus: None specified

Review type: Systematic review

Quantitative synthesis method: Narrative synthesis

Qualitative synthesis method: Not applicable

Background: Measurement of visual acuity and visual field may not be able to fully capture the impact of glaucoma on a patient’s daily life. Effects of some glaucoma treatments are only known by the patients and are not detectable or interpretable by the healthcare provider. To fully understand the impact of glaucoma and its treatment on a patient’s functioning and wellbeing, the patient’s perspective is important and should be more integrated in clinical practice and research evaluations.

Objectives: The objectives of this systematic review were to summarise the literature in view of patient-reported outcome (PRO) instruments for glaucoma and to provide guidance on how specific outcomes are best assessed based on published evidence about their content and validity.

Main findings: In this review, 53 articles addressing 27 PRO instruments were identified. Of them, 18 PROs were developed for glaucoma and nine for diverse ophthalmologic conditions. Functional status, quality of life, and disease and treatment-related factors were addressed by seven, 11 and nine instruments respectively. It was found that most of the instruments partially adhere to the pre-defined quality standards.

Authors stated that the quality of tools for assessing functional status was poor, while the glaucoma quality of life (QoL) questionnaire and the vision QoL index were well-developed QoL measures. Findings of the review showed that the item content for glaucoma patients in the Rasch-scaled QoL-tools, IVI and VCM1 needs to be improved. Also, the validity of the questionnaires to measure adherence should be improved.

Authors noted that the treatment satisfaction survey for intra-ocular pressure (IOP) was 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.

Methodology: The following databases were searched; PUBMED, CINAHL, Psycinfo and EMBASE (from 01-01-1980 to 31-12-2010) for relevant articles. In addition, the reference lists of the selected publications were hand-searched. Another search was done using the names of the instruments and the names of the first authors as search terms.

The following studies were selected: English articles describing the developmental process and/or psychometric properties of a glaucoma-specific self-report instrument capturing a PRO, vision-specific instruments developed for a broad range of ophthalmic conditions including glaucoma, and generic instruments adapted for use in glaucoma patients specifically.

Glaucoma instruments that were validated in other eye disease populations were included in this review. The following papers were excluded if the instruments were:

(a) Only used in studies without reporting information on their development or validation

(b) Developed to assess the need for or the effect of vision-related rehabilitation services

(c) Specifically developed for children

(d) Translated to another language or adapted for a specific population

(e) Developed for use in a specific minority population

(f) Only a subset of items of an instrument was further validated or

(g) If a specific scoring algorithm or item response theory was tested in an already existing PRO instrument without further validating the tool.

The titles and abstracts of all identified citations were screened by a researcher and the full text of potentially eligible articles was obtained. Identified instruments were classified and quality assessed according to well-defined criteria. All the selected and classified PROs were assessed on their quality using both the FDA guidelines and the framework of Pesudovs et al.

Applicability/external validity: Authors did not discuss the applicability or external validity of findings.

Geographic focus: Authors did not report the geographical location of included studies.

Summary of quality assessment: Authors conducted literature searches using relevant databases and on reference lists of relevant studies. Authors used appropriate methods to synthesise evidence and appraise quality of included studies, reporting each quality assessment criteria for each tool.

Authors ensured that similar studies were included in the review and appropriately reported their limitations. However, language bias was not avoided and it is not clear from the method that identification, selection and quality appraising of relevant studies were conducted by two researchers independently. Overall, a medium confidence was attributed to the conclusion about the effects of this review.