Abstract
Purpose
We investigated whether the Chinese impact of vision impairment (IVI) questionnaire is valid to generate reliable person estimates in a population-based sample.
Methods
VRQoL was measured using the 32-item Chinese version of the IVI questionnaire in the Singapore Chinese Eye Study (2009–2011), a population-based study of the prevalence and risk factors for VI and eye diseases in Chinese Singaporeans. Rasch analysis was used to assess the Chinese IVI’s response category functioning, precision, unidimensionality, targeting and differential item functioning. The ability of the Chinese IVI to discriminate participants along the spectrum of VI demonstrated criterion validity.
Results
Of the 3353 participants, 27.2 % (n = 912) had VI (presenting visual acuity <6/12, better eye). Response categories were collapsed from six to four to resolve disordered thresholds. The Chinese IVI initially demonstrated multidimensionality and was split into three scales: ‘Reading and Accessing Information’; ‘Mobility and Independence’; and ‘Emotional Well-being’. All three scales were unidimensional and demonstrated excellent range-based precision (all reliability coefficients 0.97), following removal of three misfitting items. Mean person measures decreased with worsening VI (e.g. Reading: none (7.50 logits); mild (6.99 logits); moderate (6.44 logits); and severe (3.01 logits) VI; p < 0.001).
Conclusions
A three-dimensional 29-item Chinese IVI is a valid tool to assess the impact of VI on VRQoL in a large population-based sample, comprising over a quarter of participants with VI. The 28-item English IVI is also likely to be valid for use in population-based studies; however, this must be demonstrated empirically in future studies.
Similar content being viewed by others
References
Wong, T., et al. (2014). Prevalence and causes of vision loss in East Asia: 1990–2010. British Journal of Ophthalmology, 98(5), 599–604.
Pesudovs, K. (2006). Patient-centred measurement in ophthalmology—A paradigm shift. BMC Ophthalmology. 6.
U.S. Department of Health and Human Services FDA Center for Drug Evaluation and Research, U.S. Department of Health and Human Services FDA Center for Biologics Evaluation and Research, and U.S. Department of Health and Human Services FDA Center for Devices and Radiological Health. (2006). Guidance for industry: Patient-reported outcome measures: Use in medical product development to support labeling claims: Draft guidance. Health Quality Life Outcomes, 4, 79.
Lamoureux, E., et al. (2008). Vision impairment, ocular conditions, and vision-specific function: The Singapore Malay Eye Study. Ophthalmoloy, 115(11), 1973–1981.
Chiang, P., et al. (2013). Vision impairment and major causes of vision loss impacts on vision-specific functioning independent of socioeconomic factors. Ophthalmoloy, 120(2), 415–422.
Fenwick, E., et al. (2012). Social and emotional impact of diabetic retinopathy: A review. Clinical and Experimental Ophthalmology, 40(1), 27–38.
Rovner, B., & Ganguli, M. (1998). Depression and disability associated with impaired vision: The MoVies Project. Journal of the American Geriatrics Society, 46(5), 617–619.
Rees, G., et al. (2010). Vision-specific distress and depressive symptoms in people with vision impairment. Investigative Ophthalmology and Visual Science, 51(6), 2891–2896.
Weih, L. M., Hassell, J. B., & Keeffe, J. (2002). Assessment of the impact of vision impairment. Investigative Ophthalmology and Visual Science, 43(4), 927–935.
Lamoureux, E. L., et al. (2006). The impact of vision impairment questionnaire: An evaluation of its measurement properties using Rasch analysis. Investigative Ophthalmology and Visual Science, 47(11), 4732–4741.
Lamoureux, E. L., et al. (2007). The impact of vision impairment questionnaire: An assessment of its domain structure using confirmatory factor analysis and Rasch analysis. Investigative Ophthalmology and Visual Science, 48(3), 1001–1006.
American Academy of Ophthalmology Vision Rehabilitation Committee. (2007). Vision rehabilitation for adults. In: Preferred Practice Pattern Guidelines, US Department of Health and Human Services. Editor. http://guideline.gov/content.aspx?id=11755.
Rees, G., et al. (2015). A randomised controlled trial of a self-management programme for low vision implemented in low vision rehabilitation services. Patient Education and Counseling, 98(2), 174–181.
Finger, R., et al. (2011). The impact of vision impairment on vision-specific quality of life in Germany. Investigative Ophthalmology and Visual Science, 52(6), 3613–3619.
O’Connor, P. M., et al. (2010). Validation of a quality of life questionnaire in the Pacific Island. Ophthalmic Epidemiology, 17(6), 378–386.
Gothwal, V. K., et al. (2013). Assessment of the impact of keratoconus on vision-related quality of life. Investigative Ophthalmology and Visual Science, 54(4), 2902–2910.
Szklo, M. (1998). Population-based cohort studies. Epidemiologic Reviews, 20(1), 81–90.
Wong, T. Y., & Hyman, L. (2008). Population-based studies in ophthalmology. American Journal of Ophthalmology, 146(5), 656–663.
Centers for Disease Control and Prevention. (2000). Measuring healthy days: Population assessment of health-related quality of life. Atlanta, Georgia: CDC.
Varni, J. W., & Burwinkle, T. M. (2006). The PedsQL as a patient-reported outcome in children and adolescents with Attention-Deficit/Hyperactivity Disorder: A population-based study. Health Qual Life Outcomes, 4, 26.
Wright, B. (2001). Separation, reliability and skewed distributions: Statistically different levels of performance. Rasch Measurment Transactions, 14(4), 786.
Lavanya, R., et al. (2009). Methodology of the Singapore Indian Chinese Cohort (SICC) eye study: Quantifying ethnic variations in the epidemiology of eye diseases in Asians. Ophthalmic Epidemiology, 16(6), 325–336.
Tham, Y. C., et al. (2013). Relationship between retinal vascular geometry with retinal nerve fiber layer and ganglion cell-inner plexiform layer in nonglaucomatous eyes. Investigative Ophthalmology and Visual Science, 54(12), 7309–7316.
Cheng, C. Y., et al. (2015). Association of common SIX6 polymorphisms with peripapillary retinal nerve fiber layer thickness: The Singapore Chinese Eye study. Investigative Ophthalmology and Visual Science, 56(1), 478–483.
Rooney, D., et al. (2015). Body mass index and retinopathy in Asian populations with diabetes mellitus. Acta Diabetologica, 52(1), 73–80.
Zheng, Y., et al. (2011). Prevalence and causes of visual impairment and blindness in an urban Indian population: The Singapore Indian Eye Study. Ophthalmology, 118(9), 1798–1804.
Andrich, D. (1978). Rating formulation for ordered response categories. Psychometrica, 43, 561–573.
Pesudovs, K., et al. (2007). The development, assessment, and selection of questionnaires. Optometry and Vision Science, 84(8), 663–674.
Thissen, D., & Orlando, M. (2001). Item response theory for items scored in two categories. In D. Thissen & H. Wainer (Eds.), Test scoring (pp. 73–140). Mahwah, NJ: Lawrence Erlbaum Associates, Inc.
Lamoureux, E., & Pesudovs, K. (2011). Vision-specific quality-of-life research: A need to improve the quality. American Journal of Ophthalmology, 151(2), 195-7 e2.
Bond, T. G., & Fox, C. M. (2001). Applying the Rasch model: Fundamental measurement in the human sciences. London: Lawrence Erlbaum Associates.
Pesudovs, K. (2010). Item banking: A generational change in patient-reported outcome measurement. Optometry and Vision Science, 87(4), 285–293.
Linacre, J. M. (2005). A user’s guide to Winsteps/Ministeps Rasch-Model Programs. Chicago, IL: MESA Press.
Linacre, J. M. (2002). What do Infit and Outfit, mean-square and standardized mean? Rasch Measurement Transactions, 16(2), 878.
Mallinson, T. (2007). Why measurement matters for measuring patient vision outcomes. Optometry and Vision Science, 84(8), 675–682.
Pesudovs, K., et al. (2003). The activities of daily vision scale for cataract surgery outcomes: Re-evaluating validity with Rasch analysis. Investigative Ophthalmology and Visual Science, 44(7), 2892–2899.
Stelmack, J. A., et al. (2004). Psychometric properties of the veterans affairs low-vision visual functioning questionnaire. Investigative Ophthalmology and Visual Science, 45(11), 3919–3928.
Aggarwal, A. N., Agarwal, R., & Gupta, D. (2014). Abbreviated World Health Organization Quality of Life questionnaire (WHOQOL-Bref) in north Indian patients with bronchial asthma: An evaluation using Rasch analysis. NPJ Primary Care Respiratory Medicine, 24, 14001.
Amin, L., et al. (2012). Rasch analysis of the PedsQL: An increased understanding of the properties of a rating scale. Journal of Clinical Epidemiology, 65(10), 1117–1123.
Khadka, J., et al. (2012). The importance of rating scales in measuring patient-reported outcomes. Health Qual Life Outcomes, 10, 80.
Finger, R. P., et al. (2011). The relative impact of vision impairment and cardiovascular disease on quality of life: The example of pseudoxanthoma elasticum. Health Quality Life Outcomes, 9, 113.
Fayers, P., & Hays, R. (2005). Assessing quality of life in clinical trials. Oxford: Oxford University Press.
Acknowledgments
This study was supported by grants from the National Medical Research Council (STaR/0003/2008), the Singapore Bio Imaging Consortium (C-011/2006) and the Biomedical Research Council (08/1/35/19/550). Dr. Eva Fenwick is funded by a National Health and Medical Research Council (NHMRC) Early Career Fellowship (#1072987), and Dr. Gwyn Rees is funded by an NHMRC Career Development Fellowship (#1061801). The Centre for Eye Research Australia receives Operational Infrastructure Support from the Victorian Government. The authors would like to thank Dr. Mike Linacre for his advice on conducting Rasch analysis in population-based studies.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Ethical approval
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent
Informed consent was obtained from all individual participants included in the study.
Conflicts of interest
The authors declare that they have no conflicts of interest.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Fenwick, E.K., Ong, P.G., Sabanayagam, C. et al. Assessment of the psychometric properties of the Chinese Impact of Vision Impairment questionnaire in a population-based study: findings from the Singapore Chinese Eye Study. Qual Life Res 25, 871–880 (2016). https://doi.org/10.1007/s11136-015-1141-1
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11136-015-1141-1