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Development and Psychometric Assessment of Novel Item Banks for Hereditary Retinal Diseases

Prem Senthil, Mallika, PhD1*; Khadka, Jyoti, PhD1; De Roach, John, PhD2; Lamey, Tina, PhD2; McLaren, Terri, BSc2; Campbell, Isabella2; Fenwick, Eva K., PhD3,4,5; Lamoureux, Ecosse L., PhD3,4,5; Pesudovs, Konrad, PhD, FAAO1

doi: 10.1097/OPX.0000000000001317
ORIGINAL INVESTIGATIONS
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SIGNIFICANCE This study develops psychometrically valid item banks across 10 areas of quality of life (QoL) specific to people with hereditary retinal diseases, which will enable clinicians and researchers to explore the impact of hereditary retinal diseases across all aspects of QoL.

PURPOSE The purpose of this study was to assess the psychometric properties of hereditary retinal disease QoL item banks using Rasch analysis and demonstrate the effectiveness of a computerized adaptive testing (CAT) system in obtaining precise measurement of QoL using only a few items.

METHODS The hereditary retinal disease item banks were answered by 233 participants (median age, 58 years; range, 18 to 94 years; female participants, 59%). The hereditary retinal disease item banks cover 10 QoL domains: activity limitation, mobility, emotional, social, convenience, economic, health concerns, visual symptoms, ocular comfort symptoms, and general symptoms. Rasch analysis assessed the psychometric properties of the 10 item banks and provided item calibrations for the development of CAT. Computerized adaptive testing simulations were performed to calculate the average number of items required to gain precise measurement of each QoL domain.

RESULTS The convenience, economic, visual symptoms, and the social domains formed unidimensional scales. However, the activity limitation and health concerns domains demonstrated multidimensionality and required major modifications to resolve this, which resulted in four new QoL domains, namely, reading, driving, lighting, and concerns about the disease progression. In total, 10 item banks underwent CAT simulation testing, which indicated that 8 to 12 items were required to gain precise measurement of each QoL domain.

CONCLUSIONS We have developed 10 psychometrically valid item banks to measure the QoL domains relevant to people with hereditary retinal diseases. On average, only 5 and 10 items were required to gain measurement at moderate and high precision, respectively.

1NHMRC Centre for Clinical Eye Research, Flinders University of South Australia, Adelaide, South Australia, Australia

2Australian Inherited Retinal Disease Registry and DNA Bank, Department of Medical Technology and Physics, Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia

3Centre for Eye Research Australia, University of Melbourne, the Royal Victorian Eye, and Ear Hospital, Melbourne, Victoria, Australia

4Singapore Eye Research Institute, Singapore National Eye Centre, Singapore, Singapore

5Duke–National University of Singapore Medical School, Singapore *mallika.premsenthil@flinders.edu.au

Supplemental Digital Content: Appendix Table A1, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the convenience domain.

Appendix Table A2, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the economic domain.

Appendix Table A3, available at http://links.lww.com/OPX/A367. This table that illustrates the psychometric properties of the social domain.

Appendix Table A4, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the visual symptoms domain.

Appendix Table A5, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the ocular comfort symptoms domain.

Appendix Table A6, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the general symptoms domain.

Appendix Table A7, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the activity limitation domain.

Appendix Table A8, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the health concerns domain.

Appendix Table A9, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the mobility domain.

Appendix Table A10, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the emotional domain.

Appendix Table A11, available at http://links.lww.com/OPX/A367. This table illustrates the psychometric properties of the reading, driving, and the lighting domains.

Appendix Figure A1, available at http://links.lww.com/OPX/A368. This figure illustrates the Bland and Altman plot showing the limits of agreement (mean difference and 95% confidence interval) between the Activity Limitation scale and the Reading scale.

Appendix Figure A2, available at http://links.lww.com/OPX/A369. This figure illustrates the Bland and Altman plot showing the limits of agreement (mean difference and 95% confidence interval) between the Activity Limitation scale and the Driving scale.

Appendix Figure A3, available at http://links.lww.com/OPX/A370. This figure illustrates the Bland and Altman plot showing the limits of agreement (mean difference and 95% confidence interval) between the Activity Limitation scale and the Lighting scale.

Appendix Figure A4, available at http://links.lww.com/OPX/A371. This figure illustrates the Bland and Altman plot showing the limits of agreement (mean difference and 95% confidence interval) between the Health Concerns scale and the seven-item scale.

Appendix Figure A5, available at http://links.lww.com/OPX/A372. This figure illustrates the category probability curves showing disordered thresholds for the four response categories for the Visual Symptoms scale.

Appendix Figure A6, available at http://links.lww.com/OPX/A373. This figure illustrates the flowchart showing the final item banks for hereditary retinal diseases. The boxes on the left show the original items banks, and the boxes on the right show the final item banks. New item banks identified is shown in yellow boxes, and paper-pencil short forms are identified in red boxes.

Submitted: October 23, 2017

Accepted: August 20, 2018

Funding/Support: National Health and Medical Research Council (1031838; to KP); and Australian Government Research Training Scholarship (to MPS).

Conflict of Interest Disclosure: The authors report no conflicts of interest and have no proprietary interest in any of the materials mentioned in this article.

Author Contributions and Acknowledgments: Conceptualization: MPS, JK, KP; Formal Analysis: MPS; Methodology: MPS, KP; Supervision: JK, KP; Writing – Original Draft: MPS; Writing – Review & Editing: MPS, JK, JDR, TL, TM, IC, EKF, ELL, KP.

The authors would like to thank all the members of The Royal Society for the Blind, Adelaide; Retina Australia (South Australia, Western Australia, New South Wales, Queensland, Australian Capital Territory, Victoria, and Northern Territory); Retina New Zealand; Australian Inherited Retinal Diseases Registry and DNA Bank; the Guide Dogs; and the Vision Australia 2020. The authors also would like to thank the staff of Flinders Vision. The authors also like to thank their research assistant Susan Aldhous.

Supplemental Digital Content: Direct URL links are provided within the text.

© 2019 American Academy of Optometry