Use of patient-reported outcomes in medical product development: a report from the 2009 NEI/FDA Clinical Trial Endpoints Symposium

Translation, cultural adaptation, and evaluation of the psychometric properties of the Arabic Gastroesophageal Reflux Disease Questionnaire (Ar-GerdQ)

BACKGROUND

Gastroesophageal reflux disease (GERD) is a common chronic digestive disease that affects people in different communities at different rates. Because of the absence of a validated Arabic tool to assess GERD symptoms, this study aimed to validate and culturally adapt the GERD questionnaire (GerdQ) tool to Arabic speakers.

METHODS

Patients referred for pH testing with symptoms suggestive of GERD were recruited. A cross-sectional study was conducted from March 2023 to April 2023 by administering the Arabic GERD questionnaire (Ar-GerdQ) tool on two different occasions and comparing it with the short-form leeds dyspepsia questionnaire and the Reflux Symptom Index to establish reliability and construct validity.

RESULTS

A total of 52 participants were included in the study. The results of the internal consistency analysis of the Ar-GerdQ indicate that the test has good reliability, with a Cronbach's alpha coefficient of 0.86 (95% CI: 0.75-0.91). Significant positive correlations with the short form leeds dyspepsia questionnaire (r = 0.59, P < 0.001, 95% CI: 0.29-0.78) and the reflux symptom index (r = 0.47, P = 0.01, 95% CI: 0.13-0.71) were demonstrated. Moreover, the intraclass correlation coefficient value was 0.60 (P < 0.001, 95% CI: 0.28-0.77), indicating a substantial level of agreement between the measurements.

CONCLUSIONS

Our findings indicate that the Ar-GerdQ is useful for assessing reflux disease symptoms among Arabic speakers. Effective utilization of Ar-GerdQ will reduce unnecessary endoscopic requests in primary care settings.

Quality of life in patients with CRB1-associated retinal dystrophies: A longitudinal study

PURPOSE

To assess the longitudinal vision-related quality of life among patients with CRB1-associated inherited retinal dystrophies.

METHODS

In this longitudinal questionnaire study, the National Eye Institute Visual Function Questionnaire (39 items, NEI VFQ-39) was applied at baseline, two-year follow-up, and 4-year follow-up in patients with pathogenic CRB1 variants. [Correction added on 20 November 2023, after first online publication: The preceding sentence has been updated in this version.] Classical test theory was performed to obtain subdomain scores and in particular 'near activities' and 'total composite' scores. The Rasch analysis based on previous calibrations of the NEI VFQ-25 was applied to create visual functioning and socio-emotional subscales.

RESULTS

In total, 22 patients with a CRB1-associated retinal dystrophy were included, […] with a median age of 25.0 years (interquartile range: 13-31 years) at baseline and mean follow-up of 4.0 ± 0.3 years. [Correction added on 20 November 2023, after first online publication: The preceding sentence has been updated in this version.] A significant decline at 4 years was observed for 'near activities' (51.0 ± 23.8 vs 35.4 ± 14.7, p = 0.004) and 'total composite' (63.0 ± 13.1 vs 52.0 ± 12.1, p = 0.001) subdomain scores. For the Rasch-scaled scores, the 'visual functioning' scale significantly decreased after 2 years (-0.89 logits; p = 0.012), but not at 4-year follow-up (+0.01 logits; p = 0.975). [Correction added on 20 November 2023, after first online publication: In the preceding sentence, "…after 4 years…" has been corrected to "…after 2 years…" in this version.] The 'socio-emotional' scale also showed a significant decline after 2 years (-0.78 logits, p = 0.033) and 4 years (-0.83 logits, p = 0.021).

CONCLUSION

In the absence of an intervention, a decline in vision-related quality of life is present in patients with pathogenic CRB1 variants at 4-year follow-up. Patient-reported outcome measures should be included in future clinical trials, as they can be a potential indicator of disease progression and treatment efficacy.

Efficacy of a Digital Diabetes Logbook for People With Type 1, Type 2, and Gestational Diabetes: Results From a Multicenter, Open-Label, Parallel-Group, Randomized Controlled Trial

BACKGROUND

In a randomized controlled trial, the efficacy of a digital diabetes diary regarding a reduction of diabetes distress was evaluated.

METHODS

A randomized controlled trial with a 12-week follow-up was conducted in 41 study sites across Germany. Key eligibility criteria were a diagnosis of type 1, type 2, or gestational diabetes and regular self-monitoring of blood glucose. Participants were randomly assigned (2:1 ratio) to either use the digital diabetes logbook (mySugr PRO), or to the control group without app use. The primary outcome was the reduction in diabetes distress at the 12-week follow-up. All analyses were based on the intention-to-treat population with all randomized participants. The trial was registered at the German Register for Clinical Studies (DRKS00022923).

RESULTS

Between February 11, 2021, and June 24, 2022, 424 participants (50% female, 50% male) were included, with 282 being randomized to the intervention group (66.5%) and 142 to the control group (33.5%). A total of 397 participants completed the trial (drop-out rate: 6.4%). The median reduction in diabetes distress was 2.41 (interquartile range [IQR]: -2.50 to 8.11) in the intervention group and 1.25 (IQR: -5.00 to 7.50) in the control group. The model-based adjusted between-group difference was significant (-2.20, IQR: -4.02 to -0.38, P = .0182) favoring the intervention group. There were 27 adverse events, 17 (6.0%) in the intervention group, and 10 (7.0%) in the control group.

CONCLUSIONS

The efficacy of the digital diabetes logbook was demonstrated regarding improvements in mental health in people with type 1, type 2, and gestational diabetes.

Person-reported outcomes in diabetes care: What are they and why are they so important?

In this review, we aim to show how person-reported outcomes (PROs) and person-reported experiences (PREs) can significantly contribute to the way diabetes care is delivered, the involvement of people with diabetes in diabetes care, and the collaboration between health care professionals and people with diabetes. This review focuses on the definition and measurement of PROs and PREs, the importance of PROs and PREs for person-centred diabetes care, and integrating the perspectives of people with diabetes in the evaluation of medical, psychological and technological interventions. PROs have been increasingly accepted by Health Technology Assessment bodies and are therefore valued in the context of reimbursement decisions and consequently by regulators and other health care stakeholders for the allocation of health care resources. Furthermore, the review identified current challenges to the assessment and use of PROs and PREs in clinical care and research. These challenges relate to the combination of questionnaires and ecological momentary assessment for measuring PROs and PREs, lack of consensus on a core outcome set, limited sensitivity to change within many measures and insufficient standardization of what can be considered a minimal clinically important difference. Another issue that has not been sufficiently addressed is the involvement of people with diabetes in the design and development of measures to assess PROs and PREs.

Daily Functionality of People with Low Vision: The Impact of Visual Acuity, Depression, and Life Orientation-A Cross-Sectional Study

Background

Low vision (LV) has a significant negative impact on the activities of daily life as well as on the psychological health of patients.

Objectives

The objective of this study is to investigate psychological, clinical, and demographic factors that may impact the daily functionality of patients with LV.

Methods

A convenience sample of 53 patients, meeting the WHO criteria for LV, was recruited. Questionnaires on daily functionality, depression, and life orientation (in terms of optimism/pessimism) were administered along with a semistructured personal interview. Key Findings. The main results revealed a significant negative correlation between daily functionality and depression (r = -0.423, p < 0.001). Conversely, there is a positive correlation between daily functionality and visual acuity (r = 0.415, p < 0.001), while years since diagnosis were negatively correlated with depression (r = -0.345, p < 0.001). Depression seems to be a moderate predictor of a person's daily functionality (β = -0.389, p < 0.002), followed by visual acuity (β = -0.344, p = 0.006), explaining the 31.1% of the total variance.

Conclusions

The study supports a correlation between daily functionality and both depression and visual acuity. Optimism as a personality characteristic did not factor into the prediction model for daily functionality, but it showed a strong correlation with lower levels of depressive symptoms. This highlights the potential for developing coping strategies for chronic disease management. Recommendations. The study could serve as a useful guide and may urge clinicians to pay attention to the psychological evaluation of these patients, supporting their unique emotional needs. Mental health professionals can use patients' positive resources to provide appropriate counseling and embrace the coping skills that encourage their engagement in activities of daily life.

Development and Validation of the Low Vision Severely Constricted Peripheral Eyesight (LV-SCOPE) Questionnaire

PURPOSE

To develop and validate a novel patient-reported outcome (PRO) measure to assess vision-related functioning in individuals with severe peripheral field loss (PFL).

DESIGN

Prospective outcome measure development/validation study.

METHODS

A 127-item questionnaire was developed based on a prior qualitative interview study. A total of 116 participants with severe PFL due to retinitis pigmentosa (RP) or glaucoma were recruited at the Kellogg Eye Center and completed the Likert-scaled telephone-administered questionnaire. Included participants had a horizontal extent of their visual field <20 degrees (RP) or a mixed or generalized stage 4 to 5 defect using the Enhanced Glaucoma Staging System (glaucoma) in the better seeing eye (or in 1 eye if the fellow eye visual acuity was <20/200). Response data were analyzed using exploratory factor analysis and Rasch modeling. Poorly functioning items were eliminated, confirmatory factor analysis was used to ensure scale unidimensionality, and the model was refit to produce the final instrument.

RESULTS

The final Low Vision Severely Constricted Peripheral Eyesight (LV-SCOPE) Questionnaire contains 53 items across 6 domains: mobility, object localization, object recognition, reading, social functioning, and technology. There were 74 items removed because of high missingness, poor factor loadings, low internal consistency, high local dependency, low item information, item redundancy, or differential item functioning. Using Rasch item calibrations, person ability scores could be calculated for each of the 6 unidimensional LV-SCOPE domains with good test-retest stability.

CONCLUSIONS

The LV-SCOPE Questionnaire provides a valid and reliable measure of vision-related functioning across 6 key domains relevant to individuals with severe PFL. Findings support the clinical utility of this psychometrically valid instrument.

Development and validation of the 40-item Glaucoma Visual Functioning Questionnaire

AIMS

To evaluate the psychometric properties of a newly designed questionnaire, the 40-item Glaucoma Visual Functioning Questionnaire (GVFQ-40), in a Chinese sample to capture the visual ability of patients with glaucomatous vision impairment in five domains.

METHODS

Eighty-four glaucoma suspects (controls) and 270 glaucoma patients were recruited from the Glaucoma Clinic at Zhongshan Ophthalmic Centre in this cross-sectional, observational study. All subjects completed two questionnaires during routine clinical visits: the GVFQ-40 and the validated National Eye Institute Visual Functioning Questionnaire-25 (NEI VFQ-25). The discriminant, criterion-related and construct validity of the GVFQ-40 were assessed. A subset of subjects completed the GVFQ-40 twice, with an interval of 7-21 days, to determine test-retest reliability.

RESULTS

Domain-specific and total GVFQ-40 scores were significantly higher (worse visual ability) in glaucoma patients than in controls (all p<0.001). All pairwise subgroup comparisons were statistically significant except for the 'mobility' domain comparison between the mild visual field loss and control groups (p=0.189). Significant differences between these two groups were observed in only 2 of the 12 dimensions on the NEI VFQ-25. The GVFQ-40 results demonstrated strong correlations with better-eye mean deviation and Visual Field Index (glaucoma severity measures). Exploratory factor analysis tended to confirm a three-domain structure. Test-retest intraclass correlation coefficients were higher than 0.927 for domain-specific and total GVFQ-40 scores.

CONCLUSIONS

The GVFQ-40 possesses good validity and reliability. It can be used to evaluate the impact of glaucomatous damage on visual ability and has potential in the evaluation of intervention efficacy.

TRIAL REGISTRATION NUMBER

NCT04722861.

Amblyopia and the whole child

Amblyopia is a disorder of neurodevelopment that occurs when there is discordant binocular visual experience during the first years of life. While treatments are effective in improving visual acuity, there are significant individual differences in response to treatment that cannot be attributed solely to difference in adherence. In this considerable variability in response to treatment, we argue that treatment outcomes might be optimized by utilizing deep phenotyping of amblyopic deficits to guide alternative treatment choices. In addition, an understanding of the broader knock-on effects of amblyopia on developing visually-guided skills, self-perception, and quality of life will facilitate a whole person healthcare approach to amblyopia.

The NEI VFQ-25C: Calibrating Items in the National Eye Institute Visual Function Questionnaire-25 to Enable Comparison of Outcome Measures

Purpose

To improve the usefulness of the National Eye Institute Visual Function Questionnaire-25 (NEI VFQ-25) by enabling estimation of measures on an invariant scale and comparisons between patients and across studies.

Methods

Datasets of baseline NEI VFQ-25 responses from nine studies (seven retina randomized trials, n = 2770; two low vision studies, n = 572) were combined. The method of successive dichotomizations was applied to patient ratings of the main NEI VFQ-25 and six supplemental items to estimate Rasch model parameters using the R package 'msd.' Calibrated item measures and rating category thresholds were estimated for the NEI VFQ-25, as well as for two domain-specific versions: the NEI VFQ-VF that includes only visual function items and the NEI VFQ-SE that includes only socioemotional items.

Results

Calibrated item measures were estimated from study participants (n = 3342) ranging in age from 19 to 103 years, with mean (SD) age of 69.3 (11) years and a mean logMAR visual acuity of 0.30 (Snellen 20/40). Item measure estimates had high precision (standard error range, 0.026-0.085 logit), but person measure estimates had lower precision (standard error range, 0.108-0.499 logit). Items were well targeted to most persons, but not to those with higher levels of function.

Conclusions

Calibrated item measures and rating category thresholds enable researchers and clinicians to estimate visual, socioemotional, and combined measures on an invariant scale using the NEI VFQ-25.

Translational Relevance

Applying NEI VFQ 25C calibrated item measures (software provided) to the NEI VFQ-25, users can estimate overall, visual, and socioemotional function measures for individual patients.

Interviewer Administration Corresponds to Self-Administration of the Vision Impairment in Low Luminance (VILL) Questionnaire

Purpose

To quantify the impact of the mode of administration (MOA) on scores of the Vision Impairment in Low Luminance (VILL) questionnaire.

Methods

The VILL questionnaire was implemented using different MOAs (paper, interview, electronic), in addition to a demographical survey of adult participants recruited at an outpatient eye clinic, with the initial MOA being either paper or interview. Polytomous Rasch models were used to generate person measure scores for the three subscales of the VILL questionnaire (reading, VILL_R; mobility, VILL_M; and emotional, VILL_E). Measures of agreement among the different MOAs were calculated (self-administered paper/interview, self-administered paper/self-administered electronic, and interview/self-administered electronic). An age-matched analysis was performed to control for the impact of the initial MOA, administration interval, visual acuity, and self-reported hearing difficulties.

Results

We included 309 participants (mean age, 63 ± 14 years; 61% female). Intra-class correlation coefficients were 0.930, 0.919, and 0.799 for paper versus interview assessment; 0.951, 0.959, and 0.916 for paper versus electronic; and 0.967, 0.955, and 0.907 for interview versus electronic assessment (VILL_R, VILL_M, and VILL_E, respectively). Mean differences were 0.35, 0.41, and 1.74 logits; 0.32, 0.18, and 0.68 logits; and 0.08, 0.22, and 0.63 logits, respectively. None of the mentioned factors significantly affected the results (corrected P ≥ 0.11).

Conclusions

Paper, interview, and electronic MOAs of the VILL can be considered equivalent. Reporting across the main MOAs of self-administration (paper) and interviewer-administration was unaffected by better eye visual acuity and self-reported hearing difficulties.

Translational Relevance

The results support use of the VILL questionnaire with flexible modes of administration.

Quality of life of older adults with primary open angle glaucoma using Bahasa Malaysia version of Glaucoma Quality of life 36 questionnaire

BACKGROUND

Primary open-angle glaucoma (POAG) is an age-related chronic optic neuropathy causing progressive constriction of visual field, which compromised quality of life (QoL) of older adults.

OBJECTIVE

The study aims to determine the QoL according to the severity of visual field using Bahasa Malaysia version of the Glaucoma Quality of Life- 36 (Glau-QoL 36) in older adults with POAG in Malaysia.

METHODS

A cross-sectional study was conducted in two tertiary hospitals in Malaysia: Hospital Universiti Sains Malaysia, Kelantan, and Hospital Selayang, Selangor. POAG patients who were ≥ 60 years old at the time of recruitment had minimal cataract, underwent cataract or trabeculectomy surgery at least 3 months prior and were on medical and surgical treatment. The severity of POAG was based on the modified Advanced Glaucoma Intervention Study (AGIS) score on two reliable reproducible Humphrey visual field SITA program 24-2 analysis. Face to face, one-on-one interview was conducted using validated Bahasa Malaysia version of GlauQol 36.

RESULTS

A total of 360 older adults with POAG were recruited. Majority were between ages 60-67 (38.3%) with 64 (17.8%) mild, 93 (25.8%) moderate, 115 (31.9%) severe POAG and 88 (24.4%) end-stage severity of POAG. The majority of the recruited patients were not working (88.9%) and live with their families (68.1%). There was a significant association between GlauQoL 36 score of all domains: daily living, driving, physiological well-being, self-image, anxiety, burden of treatment and confidence in healthcare with the severity of POAG (p<0.001). Increased severity of POAG was associated with decreased QoL in all GlauQoL 36 domains except confidence in healthcare. There was also a significant increase in dependency, with a majority of the end-stage were living with their families (p<0.001).

CONCLUSIONS

QoL and independency of older adults with POAG decrease with worsening of visual field defect. Addressing the problem of visual-related activities in older adults with POAG may reduce their dependency and QoL. Happy living is important to lead to healthy living among older adults with POAG.

A Scoping Review of Quality of Life Questionnaires in Glaucoma Patients

PRECIS

Multiple questionnaires exist to measure glaucoma's impact on quality of life (QoL). Selecting the right questionnaire for the research question is essential, as is patients' acceptability of the questionnaire to enable collection of relevant patient-reported outcomes.

PURPOSE

QoL relating to a disease and its treatment is an important dimension to capture. This scoping review sought to identify the questionnaires most appropriate for capturing the impact of glaucoma on QoL.

METHODS

A literature search of QoL questionnaires used in glaucoma, including patient-reported outcomes measures, was conducted and the identified questionnaires were analyzed using a developed quality criteria assessment.

RESULTS

Forty-one QoL questionnaires were found which were analyzed with the detailed quality criteria assessment leading to a summary score. This identified the top 10 scoring QoL questionnaires rated by a synthesis of the quality criteria grid, considering aspects such as reliability and reproducibility, and the authors' expert clinical opinion. The results were ratified in consultation with an international panel of ophthalmologists (N=49) from the Educational Club of Ocular Surface and Glaucoma representing 23 countries.

CONCLUSIONS

Wide variability among questionnaires used to determine vision related QoL in glaucoma and in the responses elicited was identified. In conclusion, no single existing QoL questionnaire design is suitable for all purposes in glaucoma research, rather we have identified the top 10 from which the questionnaire most appropriate to the study objective may be selected. Development of a new questionnaire that could better distinguish between treatments in terms of vision and treatment-related QoL would be useful that includes the patient perspective of treatment effects as well as meeting requirements of regulatory and health authorities. Future work could involve development of a formal weighting system with which to comprehensively assess the quality of QoL questionnaires used in glaucoma.

PRAGMATISM OF RANDOMIZED CLINICAL TRIALS ON RANIBIZUMAB FOR THE TREATMENT OF DIABETIC MACULAR EDEMA: Impact on Clinical Outcomes

PURPOSE

To evaluate the pragmatism and generalizability of randomized clinical trials (RCTs) on ranibizumab for diabetic macular edema and determine whether clinical outcomes would differ based on whether or not patients fulfill the eligibility criteria of these RCTs.

METHODS

Pragmatism and generalizability of three RCTs on ranibizumab for diabetic macular edema (DRCRnet Protocols I and T, and RESTORE) were rated using the PRECIS-2 tool. A cohort of consecutive patients with diabetic macular edema was assessed to determine whether clinical outcomes differed based on whether or not patients met the RCT eligibility criteria. Univariable and multivariable regression analyses, adjusted for baseline best-corrected visual acuity, central retinal thickness and number of injections received, were used.

RESULTS

All RCTs were rated as being more pragmatic than explanatory, with DRCRnet trials being the most pragmatic. Of the 216 eyes (176 patients) included in the cohort, 63% would have met eligibility criteria for Protocol T, 61% for Protocol I, and 56% for RESTORE. When adjusted for best-corrected visual acuity, central retinal thickness, and number of ranibizumab injections received, there were no statistically significant differences in best-corrected visual acuity or central retinal thickness found between "eligible" and "ineligible" patients.

CONCLUSION

Randomized clinical trials evaluating ranibizumab for diabetic macular edema were more pragmatic than explanatory. "Ineligible" patients still benefited from ranibizumab therapy.

Predictors of Vision-Related Quality of Life After Endothelial Keratoplasty in the Descemet Endothelial Thickness Comparison Trials

PURPOSE

To determine which baseline characteristics are associated with vision-related quality of life (QOL) after endothelial keratoplasty.

METHODS

A patient- and outcome-masked randomized clinical trial. Consecutive patients presenting with isolated endothelial disease requiring endothelial keratoplasty at Oregon Health Sciences University and Stanford University. Study eyes randomized to one of the 2 types of endothelial keratoplasty were given the national eye institute vision function questionnaire 25 at baseline and 12 months. In this prespecified secondary outcome, we assessed the role of recipient and donor characteristics as predictors of the 12-month national eye institute vision function questionnaire 25 change score.

RESULTS

The mean vision function questionnaire (VFQ) score was 74 (SD 14) at baseline and increased to 82 (SD 12) at 3 months and 87 (SD 10) at 12 months. We were unable to find a difference in vision-related QOL in study participants who underwent Descemet membrane endothelial keratoplasty compared with ultrathin Descemet stripping endothelial keratoplasty [coef -0.98, 95% confidence interval (CI) -9.27 to 7.31; P = 0.82]. In multivariable analysis, patients who underwent endothelial keratoplasty in 2 eyes had approximately 8 points higher VFQ at 12 months after the second eye than those who had only one eye enrolled (95% CI 0.10-15.72; P = 0.047). Posterior densitometry produced an approximately 1-point increase each in the VFQ change score for each 1 grayscale unit increase at baseline (95% CI 0.26-1.81; P = 0.009). Although the sample size was small, a diagnosis of pseudophakic bullous keratopathy had approximately 19-points more improvement on average compared with Fuchs (95% CI 7.68-30.00; P = 0.001).

CONCLUSIONS

Bilateral endothelial keratoplasty resulted in higher vision-related QOL compared with unilateral. Baseline densitometry, objective measure of corneal haze that predicts vision-related QOL, may play a role in monitoring disease progression.

Current Endpoints of Clinical Trials in Ulcerative Colitis: Are They Valid?

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Effect of Unilateral Endothelial Keratoplasty on Vision-Related Quality-of-Life Outcomes in the Descemet Endothelial Thickness Comparison Trial (DETECT): A Secondary Analysis of a Randomized Clinical Trial

Importance

Vision-related quality of life can be a valuable outcome for some interventions in ophthalmology. In the primary Descemet Endothelial Thickness Comparison Trial (DETECT), Descemet membrane endothelial keratoplasty (DMEK) had superior postoperative visual acuity compared with ultrathin Descemet stripping automated endothelial keratoplasty (UT-DSAEK). It is of interest to determine whether this trend extends to quality of life.

Objective

To determine the effect of UT-DSAEK and DMEK on vision-related quality of life.

Design, Setting, and Participants

A prespecified secondary analysis of a 2-surgeon patient- and outcome-masked randomized clinical trial was conducted at the Casey Eye Institute in Portland, Oregon, and Byers Eye Institute in Palo Alto, California. The study was conducted between January 20, 2015, and April 26, 2017. DETECT enrolled 38 individuals and included 50 eyes with isolated endothelial dysfunction; for this analysis, the second eye from a single participant was excluded along with any questionnaires in the first eye after second eye surgery for evaluation of 38 eyes at baseline and 3 months and 26 eyes at 12 months. Mean (SD) baseline visual acuity was 0.35 (0.31) logMAR in the DMEK arm and 0.28 (0.22) logMAR in the UT-DSAEK arm. Each arm consisted of 19 participants: 18 individuals with Fuchs dystrophy and 1 participant with pseudophakic bullous keratopathy.

Interventions

Study eyes were randomized to receive either UT-DSAEK or DMEK.

Main Outcomes and Measures

Responses to the National Eye Institute (NEI) Visual Function Questionnaire-39 (VFQ-39) administered at baseline and 3 and 12 months postoperatively were analyzed using the NEI-defined traditional subscales and composite score on a 100-point scale and with a Rasch-refined analysis.

Results

There were more women in both arms of the study (UT-DSAEK, 12 [63%]; DMEK, 11 [58%]); mean (SD) age was 68 (11) years in the UT-DSAEK arm and 68 (4) years in the DMEK arm. Overall, study participants experienced a 9.1-point improvement in NEI VFQ-39 composite score at 3 months compared with baseline (N = 38; 95% CI, 4.9-13.3; P < .001), and an 11.6-point improvement at 12 months compared with baseline (n = 26; 95% CI, 6.8-16.4; P < .001). Eyes randomized to DMEK had 0.9 points more improvement in NEI VFQ-39 composite score at 3 months compared with UT-DSAEK after controlling for baseline NEI VFQ-39 (95% CI, -6.2 to 8.0; P = .80).

Conclusions and Relevance

Improvement in vision-related quality of life was not shown to be greater with DMEK compared with UT-DSAEK.

Trial Registration

ClinicalTrials.gov identifier: NCT02373137.

Patient-reported Outcomes, Functional Assessment, and Utility Values in Glaucoma

In clinical glaucoma research, the measurement of patient reported outcomes, functional assessment of disability, and health economic impact is critical. However, valid, time-efficient and comprehensive tools are not available and several current instruments lack in the appropriate precision for measuring the various dimensions of glaucoma-related quality of life (QoL), including functioning and mobility. Furthermore, statistical methods are inconsistently and sometimes incorrectly used in otherwise sound clinical studies. Standardizing and improving methods of patient-centered data collection and analysis in glaucoma studies are imperative. This paper outlines recommendations and provides a discussion of some of the pertinent issues relating to the optimization of patient-reported outcomes research in glaucoma.

The impact of microbial keratitis on quality of life in Uganda

Background

Microbial keratitis (MK) is a frequent cause of sight loss in sub-Saharan Africa. However, no studies have formally measured its impact on quality of life (QoL) in this context.

Methods

As part of a nested case–control design for risk factors of MK, we recruited patients presenting with MK at two eye units in Southern Uganda between December 2016 and March 2018 and unaffected individuals, individually matched for sex, age and location. QoL was measured using WHO Health-Related and Vision-Related QoL tools (at presentation and 3 months after start of treatment in cases). Mean QoL scores for both groups were compared. Factors associated with QoL among the cases were analysed in a linear regression model.

Results

215 case-controls pairs were enrolled. The presentation QoL scores for the cases ranged from 20 to 65 points. The lowest QoL was visual symptom domain; mean 20.7 (95% CI 18.8 to 22.7) and the highest was psychosocial domain; mean 65.6 (95% CI 62.5 to 68.8). At 3 months, QoL scores for the patients ranged from 80 to 90 points while scores for the controls ranged from 90 to 100. The mean QoL scores of the cases were lower than controls across all domains. Determinants of QoL among the cases at 3 months included visual acuity at 3 months and history of eye loss.

Conclusion

MK severely reduces QoL in the acute phase. With treatment and healing, QoL subsequently improves. Despite this improvement, QoL of someone affected by MK (even with normal vision) remains lower than unaffected controls.

Ophthalmic Drug Discovery and Development: Regulatory Aspects of Patient Focused Drug Development in Ophthalmology

In 2009, members of the ophthalmic research community held a joint meeting with members of the Food and Drug Administration (FDA) and the National Eye Institute (NEI) to define and describe the types of patient-focused drug development (PFDD) tools used in ophthalmology. Since then numerous reports have been published which indicate that many of the questionnaires used for patient-reported outcomes (PROs) in ophthalmic clinical development lack rigor and reliability according to modern methods. In 2017, the FDA began development of a series of four methodological guidances for sponsors of clinical trials on the significance of PFDD. The new guidances delineate the FDA's thinking and commitments under the Prescription Drug User Fee Act to implement a more structured approach to the assessment of risks and benefits in clinical trials. In these guidances, the FDA provides steps that drug and device manufacturers should follow, not only to obtain, but also to develop reliable and validated tools that measure patients' experience in clinical trials. Subsequent efforts have resulted in the development and validation of PROs specifically for ophthalmology. The purpose of this paper is to assesses the PROs currently used in ophthalmology and to provide practical strategies for incorporating them into clinical trials.

Psychometric properties of the Glaucoma Quality of Life-15 questionnaire: Use of explanatory factor analysis

Purpose

The purposes of this study were to validate the Persian translation of the Glaucoma Quality of Life-15 (GQL-15) questionnaire, evaluate its psychometric properties, and identify new composite items and item numbers.

Methods

This cross-sectional study was conducted from August to November 2016, at the Glaucoma Clinic of the Ophthalmology Department at Shiraz University of Medical Sciences, Iran. One hundred ninety patients with glaucoma were enrolled. Habitual-corrected visual acuity (HCVA), intraocular pressure (IOP), slit-lamp biomicroscopy, fundus exam, and mean deviation (MD) of the visual field were recorded in the course of clinical examination by glaucoma professional. Psychometric properties, i.e. test–retest reliability, internal consistency, content validity, and construct validity were evaluated with factor analysis. Based on the Disc Damage Likelihood Scale (DDLS), patients were stratified to mild, moderate, and severe disc damage. The association between the GQL-15 scores and disease severity (mild, moderate and severe) were evaluated by the analysis of variance (ANOVA).

Results

Of 190 eligible glaucoma patients, reliable clinical data were available for 140 participants. Mean age [standard deviation (SD)] of the patients was 58.7 (13.3) years. Cronbach's α coefficient ranged from 0.74 to 0.91, and the correlation coefficient for total score was 0.53. The content validity ratio (CVR) was 0.91 based on evaluations in expert panel. Exploratory factor analysis (EFA) based on eigenvalue higher than one identified two factors after varimax rotation for the GQL-15 which explained 66.5% of the total variance. Discriminant validity analysis disclosed statistically significant differences in mean quality of life scores between levels of disease severity.

Conclusion

The Persian version of the GQL-15 is a reliable and valid questionnaire for use in glaucoma clinics as a complementary tool for evidence-based decision-making.

An Italian Translation and Validation of the near Activity Visual Questionnaire (NAVQ)

Purpose

To validate the Near Activity Vision Questionnaire (NAVQ) in Italian to allow the assessment of presbyopia corrections in Italian-speaking patients.

Methods

An Italian version of the NAVQ was arranged through several steps: an initial forward translation (from English to Italian), a backward translation (from Italian to English), and finally a consensual version to check against the original NAVQ. This prospective study enrolled native Italian-speaking presbyopic patients with corrected distance visual acuity of 0.20 logMAR or better in each eye and free of ocular anomalies. Six different groups of patients were asked to complete the questionnaire: emerging presbyopic patients, reading spectacle users, multifocal spectacle users, multifocal contact lens (CL) wearers, monovision CL wearers, and monofocal intraocular lens patients. Subjects were asked to answer the questionnaire again 2 weeks after the first completion.

Results

A total of 207 subjects completed the questionnaire. Data analysis showed good internal consistency (Cronbach α = 0.93) and factorial validity with only one factor explaining 62.0% of the variance. Test-retest reliability was extremely good (ICC = 0.92) as well as discriminatory power of the questionnaire's ability to discriminate between subjects with different forms of presbyopic correction.

Conclusions

The Italian version of the NAVQ matches the properties of the original English version. It is a valid instrument to evaluate near activity visual quality of presbyopic Italian speakers.

Development of a new Rasch-based scoring algorithm for the National Eye Institute Visual Functioning Questionnaire to improve its interpretability

BACKGROUND

The NEI VFQ-25 has undergone psychometric evaluation in patients with varying ocular conditions and the general population. However, important limitations which may affect the interpretation of clinical trial results have been previously identified, such as concerns with reliability and validity. The purpose of this study was to evaluate the National Eye Institute Visual Functioning Questionnaire (NEI VFQ-25) and make recommendations for a revised scoring structure, with a view to improving its psychometric performance and interpretability.

METHODS

Rasch Measurement Theory analyses were conducted in two stages using pooled baseline NEI VFQ-25 data for 2487 participants with retinal diseases enrolled in six clinical trials. In stage 1, we examined: scale-to-sample targeting; thresholds for item response options; item fit statistics; stability; local dependence; and reliability. In stage 2, a post-hoc revision of the scoring structure (VFQ-28R) was created and psychometrically re-evaluated.

RESULTS

In stage 1, we found that the NEI VFQ-25 was mis-targeted to the sample, and had disordered response thresholds (15/25 items) and mis-fitting items (8/25 items). However, items appeared to be stable (differential item functioning for three items), have minimal item dependency (one pair of items) and good reliability (person-separation index, 0.93). In stage 2, the modified Rasch-scored NEI VFQ-28-R was assessed. It comprised two broad domains: Activity Limitation (19 items) and Socio-Emotional Functioning (nine items). The NEI VFQ-28-R demonstrated improved performance with fewer disordered response thresholds (no items), less item misfit (three items) and improved population targeting (reduced ceiling effect) compared with the NEI VFQ-25.

CONCLUSIONS

Compared with the original version, the proposed NEI VFQ-28-R, with Rasch-based scoring and a two-domain structure, appears to offer improved psychometric performance and interpretability of the vision-related quality of life scale for the population analysed.

Assessment of the Incorporation of Patient-Centric Outcomes in Studies of Minimally Invasive Glaucoma Surgical Devices

IMPORTANCE

Minimally invasive glaucoma surgical (MIGS) devices are one option for lowering intraocular pressure in patients with glaucoma.

OBJECTIVE

To examine how often existing clinical studies of MIGS devices registered on ClinicalTrials.gov measure patient-centric outcomes that patients value directly.

DESIGN, SETTING, AND PARTICIPANTS

We searched ClinicalTrials.gov, a registry of publicly and privately supported clinical studies, on February 20, 2015, for records of MIGS device studies involving patients with glaucoma. Two investigators independently abstracted study design and outcome details from eligible records. We classified outcomes as patient-centric or not patient-centric using a prespecified definition.

MAIN OUTCOMES AND MEASURES

Proportion of patient-centric and nonpatient-centric outcomes registered on ClinicalTrials.gov.

RESULTS

We identified 51 eligible studies specifying 127 outcomes. Reduction in intraocular pressure was the most frequent outcome specified (78/127; 61%) and a primary outcome in 41 studies. Patient-centric outcomes-such as adverse events (n = 19; 15%), topical medication use (n = 16; 13%), visual acuity (n = 4; 3%), and health-related quality of life (n = 1; 1%)-were less frequently specified (n = 40; 32%) and a primary outcome in only 12 studies.

CONCLUSION AND RELEVANCE

Patient-centric outcomes that provide insight into the relative desirability and acceptability of the benefits and risks of MIGS devices are not well represented in current clinical studies.

Quality of Life in the Tube Versus Trabeculectomy Study

PURPOSE

To report the vision-specific quality-of-life (QoL) outcomes in the Tube Versus Trabeculectomy (TVT) Study.

DESIGN

Multicenter randomized clinical trial.

METHODS

Setting: Seventeen clinical centers.

STUDY POPULATION

Patients 18-85 years of age with medically uncontrolled glaucoma who had previous cataract and/or glaucoma surgery.

INTERVENTIONS

Tube shunt (350-mm² Baerveldt glaucoma implant) or trabeculectomy with MMC.

MAIN OUTCOME MEASURES

Vision-specific QoL using the NEI VFQ-25 and estimation of minimally important differences (MID) were the main outcome measures. Cross-sectional distribution- and anchor-based approaches were used to estimate MID. Clinical anchor measures included the mean deviation (MD) and logMAR visual acuity (VA) measurements. Clinically significant changes in anchor were defined as ≥2 dB MD and ≥0.2 logMAR.

RESULTS

No significant differences in composite scores were observed between treatment groups, and no significant change in scores were seen over time. Mean (SD; range) values of clinical anchors at baseline were -16.6 (9.3; -32 to -0.5) dB for the surgical eye and 0.2 (0.3; -0.1 to 1.3) logMAR VA in the better-vision eye. For anchor-based cross-sectional analysis, composite score MID (95% CI) was 6.3 (4.6-7.9) for better-eye VA and 1.4 (0.9-1.9) for surgical eye MD. Distribution-based MID for the composite score was 6.0.

CONCLUSIONS

Trabeculectomy and tube shunt surgery had similar impact on patient-reported vision-specific QoL measured using the NEI VFQ-25. In this cohort of patients with advanced glaucoma, MIDs varied depending on the clinical anchor used. Distribution-based MIDs corresponded well with anchor-based MIDs based on VA measures. The MID values reported here may be useful for others wishing to interpret NEI VFQ-25 scores in their advanced glaucoma patient cohort.

Neuroprosthetics and the science of patient input

Safe and effective neuroprosthetic systems are of great interest to both DARPA and CDRH, due to their innovative nature and their potential to aid severely disabled populations. By expanding what is possible in human-device interaction, these devices introduce new potential benefits and risks. Therefore patient input, which is increasingly important in weighing benefits and risks, is particularly relevant for this class of devices. FDA has been a significant contributor to an ongoing stakeholder conversation about the inclusion of the patient voice, working collaboratively to create a new framework for a patient-centered approach to medical device development. This framework is evolving through open dialogue with researcher and patient communities, investment in the science of patient input, and policymaking that is responsive to patient-centered data throughout the total product life cycle. In this commentary, we will discuss recent developments in patient-centered benefit-risk assessment and their relevance to the development of neural prosthetic systems.

Health-related quality of life in patients with primary open-angle glaucoma. An Italian multicentre observational study

PURPOSE

As a progressive condition, glaucoma may impair health-related quality of life (HRQoL), due to vision loss and other factors. This study evaluated HRQoL in a cohort of patients treated for primary open-angle glaucoma (POAG) and assessed its association with clinical features.

METHODS

This was an Italian, multicentre, cross-sectional, observational study with the subgroup of newly diagnosed patients with POAG prospectively followed up for one year. Patients with previous or new diagnosis (or strong clinical suspicion) of POAG aged >18 years were considered eligible. Information was collected on demographic characteristics, medical history, clinical presentation and POAG treatments. HRQoL was measured using the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25) and Glaucoma Symptom Scale (GSS). Subscale and total scores were obtained and a Pearson correlation coefficient between instruments' scores calculated.

RESULTS

A total of 3227 patients were enrolled from 2012 to 2013 and 3169 were analysed. Mean age was 66.9 years. A total of 93.8% had a previous diagnosis (median duration: 8.0 years). Median values for mean deviation and pattern standard deviation were 3.9 and 3.6 dB, respectively. Mean scores on most subscales of the NEI-VFQ-25 exceeded 75.0 and mean GSS subscale scores ranged between 70.8 and 79.7 (with a total mean score of 74.8). HRQoL scores on both scales were significantly inversely associated with POAG severity.

CONCLUSION

In this large sample of Italians treated for POAG, disease severity was limited and HRQoL scores were high. QoL decreased with advancing disease severity. These findings confirm the role of vision loss in impairing QoL in POAG, underlying the importance of timely detection and appropriate treatment.

Quality of Life in Glaucoma: A Review of the Literature

The ultimate goal of glaucoma management is the preservation of patients’ visual function and quality of life (QoL). The disease itself as well as the medical or surgical treatment can have an enormous impact on a patient’s QoL. Even the mere diagnosis of a chronic, irreversible, potentially blinding disorder can adversely affect the patient’s sense of well-being and QoL by eliciting significant anxiety. Patients with primary open-angle glaucoma rarely present with visual symptoms, at least early in the course of the disease. A better understanding of patient-reported QoL can improve patient–physician interaction and enhance treatment adherence by customizing treatment options based on individual patient profile, thus optimizing long-term prognosis. These aspects are summarized and critically appraised in this article.

Risk factors for low vision related functioning in the Mycotic Ulcer Treatment Trial: a randomised trial comparing natamycin with voriconazole

BACKGROUND/AIMS

The Mycotic Ulcer Treatment Trial I (MUTT I) was a double-masked, multicentre, randomised controlled trial, which found that topical natamycin is superior to voriconazole for the treatment of filamentous fungal corneal ulcers. In this study, we determine risk factors for low vision-related quality of life in patients with fungal keratitis.

METHODS

The Indian visual function questionnaire (IND-VFQ) was administered to MUTT I study participants at 3 months. Associations between patient and ulcer characteristics and IND-VFQ subscale score were assessed using generalised estimating equations.

RESULTS

323 patients were enrolled in the trial, and 292 (90.4%) completed the IND-VFQ at 3 months. Out of a total possible score of 100, the average VFQ score for all participants was 81.3 (range 0-100, SD 23.6). After correcting for treatment arm, each logMAR line of worse baseline visual acuity in the affected eye resulted in an average 1.2 points decrease on VFQ at 3 months (95% CI -1.8 to 0.6, p<0.001). Those who required therapeutic penetrating keratoplasty had an average of 25.2 points decrease on VFQ after correcting for treatment arm (95% CI -31.8 to -18.5, p<0.001). Study participants who were unemployed had on average 28.5 points decrease on VFQ (95% CI -46.9 to -10.2, p=0.002) after correcting for treatment arm.

CONCLUSIONS

Monocular vision loss from corneal opacity due to fungal keratitis reduced vision-related quality of life. Given the relatively high worldwide burden of corneal opacity, improving treatment outcomes of corneal infections should be a public health priority.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov Identifier: NCT00996736.

Vision-Related Quality-of-Life Outcomes in the Mycotic Ulcer Treatment Trial I: A Randomized Clinical Trial

IMPORTANCE

Given the limitations in health care resources, quality-of-life measures for interventions have gained importance.

OBJECTIVE

To determine whether vision-related quality-of-life outcomes were different between the natamycin and voriconazole treatment arms in the Mycotic Ulcer Treatment Trial I, as measured by an Indian Vision Function Questionnaire.

DESIGN, SETTING, AND PARTICIPANTS

Secondary analysis (performed October 11-25, 2014) of a double-masked, multicenter, randomized, active comparator-controlled, clinical trial at multiple locations of the Aravind Eye Care System in South India that enrolled patients with culture- or smear-positive filamentous fungal corneal ulcers who had a baseline visual acuity of 20/40 to 20/400 (logMAR of 0.3-1.3).

INTERVENTIONS

Study participants were randomly assigned to topical voriconazole, 1%, or topical natamycin, 5%.

MAIN OUTCOMES AND MEASURES

Subscale score on the Indian Vision Function Questionnaire from each of the 4 subscales (mobility, activity limitation, psychosocial impact, and visual function) at 3 months.

RESULTS

A total of 323 patients were enrolled in the trial, and 292 (90.4%) completed the Indian Vision Function Questionnaire at 3 months. The majority of study participants had subscale scores consistent with excellent function. After adjusting for baseline visual acuity and organism, we found that study participants in the natamycin-treated group scored, on average, 4.3 points (95% CI, 0.1-8.5) higher than study participants in the voriconazole-treated group (P = .046). In subgroup analyses looking at ulcers caused by Fusarium species and adjusting for baseline best spectacle-corrected visual acuity, the natamycin-treated group scored 8.4 points (95% CI, 1.9-14.9) higher than the voriconazole-treated group (P = .01). Differences in quality of life were not detected for patients with Aspergillus or other non-Fusarium species as the causative organism (1.5 points [95% CI, -3.9 to 6.9]; P = .52).

CONCLUSIONS AND RELEVANCE

We found evidence of improvement in vision-related quality of life among patients with fungal ulcers who were randomly assigned to natamycin compared with those randomly assigned to voriconazole, and especially among patients with Fusarium species as the causative organism. Incorporation of quality-of-life measures in clinical trials is important to fully evaluate the effect of the studied interventions.

TRIAL REGISTRATION

clinicaltrials.gov Identifier:NCT00996736.

Patient experiences in retinal trials: a cross-sectional study

Background

Patient-centered care recognizes the obligation to understand and meet patient’s expectations. An individual’s satisfaction has been found to affect health-related decisions and treatment-related behaviours, which in turn affect medical compliance, follow-up, the success of treatment and the appropriate use of services. We studied the expectations, experiences and satisfaction of patients who participated in clinical trials for retinal diseases at the Sydney Eye Hospital.

Methods

The study was undertaken at the research clinic of the major public quaternary eye hospital in New South Wales, Australia. A 37-question survey was conducted on patients enrolled in or who had finished a clinical trial for macular disease in the 12 months preceding this study in November 2012. Patient satisfaction was assessed using close-ended, multiple choice questions. First, the decision making process for entering into the clinical trial was evaluated. Then the level of patient understanding and experience during the study was assessed. Finally, there was a series of questions to gauge the participants’ perception of trial outcomes and overall impression gained from the experience.

Results

Eighty patients completed the questionnaire. Overall patient satisfaction was high with the majority of patients stating they would recommend participation in a retinal clinical trial (94 %) and participate in a subsequent trial (78 %). Most patients rated themselves as the most important factor in making the decision to join a trial. Patients felt well informed and expectations were generally felt to be met, however 14 % did not believe that they could withdraw from the study voluntarily. The most common reasons for trial participation were to contribute to medical science and to have improved treatment outcomes.

Conclusions

We found that patients generally found participation in retinal clinical trials to be a positive experience. Factors contributing to dissatisfaction mainly related to inconvenience experienced by transportation and waiting times. We also found that patients felt well informed about the study, but some did not have a complete understanding of their rights, which had been communicated to them when they entered the study. There were both altruistic and self-motivated reasons behind patients’ decisions to join a retinal trial.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-015-0071-6) contains supplementary material, which is available to authorized users.

Diagnosing the severity of dry eye: a clear and practical algorithm

Dry eye disease (DED) is a distressing ocular condition. Due to its multifactorial nature, clinical and biological signs of DED can be inconsistent and sometimes discordant with symptomatology. Consequently, no gold-standard model for determining DED severity exists. This can impact treatment decisions and complicate evaluation of disease progression, particularly within the stringent context of clinical trials. The multinational ODISSEY European Consensus Group is comprised of ophthalmologists who contend with ocular surface disease issues on a daily basis. This group convened to establish a clear and practical algorithm for evaluation and diagnosis of severe DED. Using a consensus-based approach, they assessed 14 commonly used DED severity criteria. The panel agreed that following confirmed DED diagnosis, just two criteria, symptom-based assessment and corneal fluorescein staining were sufficient to diagnose the presence of severe DED in the majority of patients. In the event of discordance between signs and symptoms, further evaluation using additional determinant criteria was recommended. This report presents the ODISSEY European Consensus Group recommended algorithm for DED evaluation, which facilitates diagnosis of severe disease even in the event of discordance between signs and symptoms. It is intended that this algorithm will be useful in a clinical and developmental setting.

National Eye Institute Visual Function Questionnaire: usefulness in glaucoma

The National Eye Institute Visual Function Questionnaire 25 (NEI-VFQ-25) is the most commonly used patient-reported outcome measure to assess vision-related quality of life in patients with glaucoma. Glaucoma negatively affects the composite and several NEI-VFQ subscale scores; this effect is correlated with the severity of glaucomatous visual field loss. Contrast sensitivity, glare, and dark adaptation are potential items that could be added to the NEI-VFQ to make it more responsive to changes in vision-related quality of life in patients with glaucoma.

Visual Function Endpoints to Enable Dry AMD Clinical Trials

The slow progression of non-exudative age-related macular degeneration (dry AMD) presents challenges for drug discovery. The standard endpoint used for ophthalmic clinical trials, best-corrected visual acuity, is insensitive to the early stages and slow progression of dry AMD. Effective drug discovery for dry AMD treatments will therefore require novel applications of more effective visual function endpoints. This review will present candidates for visual function endpoints for dry AMD clinical trials. The promising visual assessments include contrast sensitivity, reading speed, microperimetry, and dark adaptation. Their adoption as exploratory endpoints in future trials will be critical for determining their accuracy, precision, and applicability, and ultimately determine their value for drug discovery.

The challenges in improving outcome of cataract surgery in low and middle income countries

Cataract is the leading cause of blindness globally and surgery is the only known measure to deal with it effectively. Providing high quality cataract surgical services is critical if patients with cataract are to have their sight restored. A key focus of surgery is the outcome of the procedure. In cataract surgery this is measured predominantly, using visual acuity. Population- and hospital-based studies have revealed that the visual outcome of cataract surgery in many low and middle income settings is frequently sub-optimal, often failing to reach the recommended standards set by the World Health Organization (WHO). Another way of measuring outcome of cataract surgery is to ask patients for their views on whether surgery has changed the functioning of their eyes and their quality of life. There are different tools available to capture patient views and now, these patient-reported outcomes are becoming more widely used. This paper discusses the visual outcome of cataract surgery and frames the outcome of surgery within the context of the surgical service, suggesting that the process and outcome of care cannot be separated. It also discusses the components of patient-reported outcome tools and describes some available tools in more detail. Finally, it describes a hierarchy of challenges that need to be addressed before a high quality cataract surgical service can be achieved.

The importance of rating scales in measuring patient-reported outcomes

Background

A critical component that influences the measurement properties of a patient-reported outcome (PRO) instrument is the rating scale. Yet, there is a lack of general consensus regarding optimal rating scale format, including aspects of question structure, the number and the labels of response categories. This study aims to explore the characteristics of rating scales that function well and those that do not, and thereby develop guidelines for formulating rating scales.

Methods

Seventeen existing PROs designed to measure vision-related quality of life dimensions were mailed for self-administration, in sets of 10, to patients who were on a waiting list for cataract extraction. These PROs included questions with ratings of difficulty, frequency, severity, and global ratings. Using Rasch analysis, performance of rating scales were assessed by examining hierarchical ordering (indicating categories are distinct from each other and follow a logical transition from lower to higher value), evenness (indicating relative utilization of categories), and range (indicating coverage of the attribute by the rating scale).

Results

The rating scales with complicated question format, a large number of response categories, or unlabelled categories, tended to be dysfunctional. Rating scales with five or fewer response categories tended to be functional. Most of the rating scales measuring difficulty performed well. The rating scales measuring frequency and severity demonstrated hierarchical ordering but the categories lacked even utilization.

Conclusion

Developers of PRO instruments should use a simple question format, fewer (four to five) and labelled response categories.