Epidemiology and social determinants of visual impairment and diabetic retinopathy

EPIDEMIOLOGY AND SOCIAL DETERMINANTS OF VISUAL IMPAIRMENT AND DIABETIC RETINOPATHY ZHENG YINGFENG (M.D.) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY DEPARTMENT OF OPHTHALMOLOGY NATIONAL UNIVERSITY OF SINGAPORE 2012 DECLARATION I hereby declare that the thesis is my original work and it has been written by me in its entirety. I have duly acknowledged all the sources of information which have been used in the thesis. This thesis has also not been submitted for any degree in any university previously. _________________ Zheng Yingfeng 30 November 2012 I THESIS COMMITTEE AND SUPERVISORS Thesis Advisory Committee (TAC): Lamoureux L. Ecosse, PhD., Adjunct Associate Professor, Department of Ophthalmology, National University of Singapore (Chairman) Aung Tin, Ph.D., M.D., Professor, Department of Ophthalmology, National University of Singapore (Member) Wong Tien Yin, Ph.D., M.D., Professor, Department of Ophthalmology, National University of Singapore (Member) Thesis Supervisors: Wong Tien Yin, Ph.D., M.D., Professor, Department of Ophthalmology, National University of Singapore (Main) Aung Tin, Ph.D., M.D., Professor, Department of Ophthalmology, National University of Singapore (Co-supervisor) II ACKNOWLEDGEMENTS This dissertation was based on three large population-based studies with data collected over nearly seven years of epidemiological research. This work would have been impossible without the contribution of many investigators, colleagues, coauthors, staff and participants of the Singapore Epidemiology of Eye Disease (SEED) study. The epidemiological research was funded by the Biomedical Research Council (BMRC) and National Medical Research Council (NMRC), Singapore There are many people who have supported and guided me through the journey. First, I would like to acknowledge Dr. Tien Wong, my advisor, mentor, and friend, for his unwavering support and continual guidance. I am indebted to Dr. Tin Aung and Dr. Ecosse Lamoureux for serving in my Thesis Committee and for their inspiration and advice on analyses and methodology. I am also grateful to Dr. Seang-Mei Saw, Dr. Jie-Jin Wang, and Dr. Paul Mitchell for their valuable input in my publications. Second, I am grateful to Aidah Idris, Sister Chye-Fong Peck, Farook Abdul, Maisie Ho, Haslina Hamzah, and Sangeetha Nagarajah for coordinating the studies and data management. I am thankful to Renyi Wu, Ching-Yu Cheng, Carol Cheung, Kamran Ikram and the whole epidemiology team in Singapore Eye Research Institute (SERI). My special thanks to Chenwei Pan, Charumathi Sabanayagam, Peggy Chiang, Belinda Cornes, and Jennifer Ding for their help and guidance. I am also thankful to Wan-Ling Wong for encouragement and statistical support. Third, I am truly blessed to have the wholehearted backing of Dr. Mingguang He, vice director of the Zhongshan Ophthalmic Center. He encouraged me to pursue my Ph.D. and inspired me to devote my career to public health ophthalmology. III Finally, I am grateful to my family for their support throughout. I dedicate this thesis to my wife, Xian-Chai, for her daily sacrifice and support that enable me to pursue my goals. IV TABLE OF CONTENTS Declaration Page . i Thesis Committee and Supervisors . ii Acknowledgements iii Table of Contents v Summary viii List of Tables x List of Figures . xii List of Abbreviations . xiii List of Publications . xv CHAPTERS I. Background and global literature review . Introduction and historical perspective . Definition of social determinants Are there health inequalities in eye diseases? Race/ethnicity . Age and gender . Socioeconomic status (SES) . Geographic variation and neighborhood-level SES Literacy and health literacy . Utilization of eye care services . 10 Social gradient 10 Are inequalities avoidable? . 11 Genetics . 12 Individual responsibility . 12 Efficiency versus equality . 13 Are interventions to reduce health inequalities cost-effective? 14 What are the solutions? . 15 Commitment and leadership . 15 Healthcare and health insurance . 15 Financial aid 16 Better metrics 17 How relevant is the issue for Singapore? 17 Conclusions . 19 Chapter I references 20 II. Rationale, study overview, and methods . 32 Statement of the problem and rationale 33 Specific aims . 35 Study populations 35 Recruitment . 36 Study procedures and definitions 36 Thesis structure . 40 Chapter references . 43 III. Manuscript 1: Ethnic and SES differences in prevalence of visual impairment in adult populations in urban Asia 52 Introduction . 53 Methods 54 Results . 56 Discussions . 58 V Chapter references . 62 IV. Manuscript 2: Ethnic and SES difference in needs for eye care in adults living in urban Asia . 73 Introduction . 74 Methods 75 Results . 79 Discussions . 82 Chapter references . 86 V. Manuscript 3: Association of area-level SES measures with visual impairment . 100 Introduction . 101 Methods 102 Results . 104 Discussions . 105 Chapter references . 109 VI. Manuscript 4: Marital status and its relationship to the risk and pattern of visual impairment 116 Introduction 117 Methods 118 Results . 119 Discussions . 120 Chapter references . 124 VII. Manuscript 5: Association of limited literacy with visual impairment and poor visual functioning 132 Introduction . 133 Methods 134 Results . 136 Discussions . 138 Chapter references . 143 VIII. Manuscript 6: Language barrier and its relationship to diabetes and diabetic retinopathy . 151 Introduction . 152 Methods 153 Results . 157 Discussions . 161 Chapter references . 165 IX. Manuscript 7: Impact of migration and acculturation on prevalence of type diabetes and related eye complications in Indians living in a newly urbanized society . 174 Introduction . 175 Methods 176 Results . 179 Discussions . 181 Chapter references . 185 X. Summary and recommendations for future research 194 Summary . 195 Main strengths and limitations of the study 198 Future direction . 199 VI Development of new tools for measuring social determinants of health 200 Prospective assessment of social determinants on eye disease and visual impairment 200 Evaluation of cost-effectiveness of interventions . 201 Need for a multi-causal approach . 201 Appendices 207 Appendix 1. Additional tables 207 Appendix 2. Singapore Consortium of Cohort Studies Questionnaire 229 Appendix 3. Permissions required to use of published articles . 265 VII SUMMARY Background: Social determinants of health are referred to as the social and cultural conditions including socioeconomic status (SES) and other factors (e.g., ethnicity, gender, neighborhoods, literacy, marital status, and migration status) that influence individual and group differences in health. Social determinants influence a wide range of systemic diseases (e.g., heart disease, diabetes), but the impacts of social determinants on visual impairment (VI) and major eye disease such as diabetic retinopathy (DR) remain less well examined. Addressing these social determinants is a key concern of public health policies in Asia, a continent home to 60% of the world’s blindness population. This thesis examines social determinants of VI and DR in a multiethnic Asian population in Singapore. Methods: The Singapore Epidemiology of Eye Disease (SEED) study comprises population-based, cross-sectional studies of Singapore-resident ethnic Malays, Indians and Chinese aged ≥40 years, examined between 2004 and 2011, using the same study protocol. Participants underwent standardized ophthalmic and physical assessments. VI and blindness were defined using both the United States and WHO definitions. Social determinants and other risk factors were assessed from interviewer-administered questionnaires. Presence of DR was determined from grading retinal photographs. Manuscript describes the ethnic and SES difference in prevalence of VI. Manuscript describes the ethnic and SES differences in needs for specific eye care services. Manuscript examines the association of area-level SES measures with VI. Manuscript examines the relationships of marital status with VI. Manuscript examines the association of literacy with VI and visual function. Manuscript examines the relationship of English proficiency with type-2 diabetes and DR in ethnic Indians. Manuscript examines the association of migration and acculturation with diabetes and diabetes-related eye complications (i.e., DR and cataract) in ethnic Indians. VIII Results: A total of 10,033 persons (75.7% response rate), comprising 3,280 Malays, 3,400 Indians and 3,353 Chinese, had their data available. Our analyses identified a variety of social determinants for vision health, not only traditional factors such as ethnicity, education and income, but also a range of new social determinants, including area-level SESs (Odds Ratio (OR) for VI, 2.13; 95% CI, 1.05 to 3.36; low versus high area-level SES summary score), literacy (OR for VI 3.24; 95% CI, 2.51 to 4.19; inadequate versus adequate literacy), marital status (OR for VI, 1.50; 95% CI, 1.19 to 1.90; single versus married), English proficiency (OR for DR, 1.20; 95% CI, 1.05 to 1.70; Tamil-speaking versus English-speaking Indians with diabetes), and migration status (OR for DR, 1.73; 95% CI, 1.02 to 2.92; 2nd versus 1st generation Indian immigrants with diabetes). Conclusion: Prevalence of VI and DR vary significantly across ethnicity, education, income, neighborhoods, literacy, marital status, language skill, and migration status in Singapore. These data provide the first major population-based data on the impacts of social and cultural issues affecting eye health in Asians. Future work needs to investigate the causal pathways and to assess how investment addressing these social determinants can improve health and reduce health inequalities. IX Cheung,Tin Aung,Seang-Mei Saw,Tien Y. Wong Licensed content date October 2012 Licensed content volume number 119 Licensed content issue number 10 Number of pages Start Page 2119 End Page 2124 Type of Use reuse in a thesis/dissertation Portion full article Format electronic Are you the author of this Elsevier Yes article? Will you be translating? 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Zheng Y, Lamoureux E, Finkelstein E, Wu R, Lavanya R, Chua D, Aung T, Saw SM, Wong TY. Independent impact of area-level socioeconomic measures on visual impairment. Invest Ophthalmol Vis Sci. 2011 Nov 11;52(12):8799-805. A reprint of this material must include full article citations and acknowledge ARVO as the copyright holder. Best regards, Debbie Chin Production Coordinator IOVS Association for Research in Vision and Ophthalmology 1801 Rockville Pike, Suite 400 Rockville MD 20852 USA Direct: +1.240.221.2926 | Main: +1.240.221.2900 | Fax: +1.240.221.0370 www.arvo.org Save the date 2013 ARVO Annual Meeting May – │Seattle www.arvo.org/am From: yingfengzheng@gmail.com [mailto:yingfengzheng@gmail.com] On Behalf Of Yingfeng Zheng Sent: Saturday, November 10, 2012 10:04 AM To: Debbie Chin Subject: Request for Permission to Reproduce Copyright Work 10/11/2012 Debbie Chin Association for Research in Vision and Ophthalmology 12300 Twinbrook Parkway Suite 250 Rockville, Maryland 20852 United States Dear Debbie, Request for Permission to Reproduce Copyright Work I am a graduate student in the National University of Singapore ("NUS"), and am currently working on a thesis for submission to NUS as part of my academic program. My thesis is likely to be published electronically by NUS on the internet and on NUS' own intranet, and copies of my thesis will be made available to NUS and end users. My thesis aims to evaluate the social determinants of visual impairment and diabetic retinopathy in a multiethnic Asian population in Singapore. I am writing to seek your kind permission to use and reproduce, for purposes of submission, publication and distribution of my thesis as described above, the following works for which I understand Investigative Ophthalmology and Visual Science to be the copyright owner: (a) The whole publication of Zheng Y, Lamoureux EL, Chiang PP, Cheng CY, Anuar AR, Saw SM, Aung T, Wong TY. Literacy is an independent risk factor for vision impairment and poor visual functioning. Invest Ophthalmol Vis Sci. 2011 Sep 29;52(10):7634-9. (b) The whole publication of Zheng Y, Lamoureux E, Finkelstein E, Wu R, Lavanya R, Chua D, Aung T, Saw SM, Wong TY. Independent impact of area-level socioeconomic measures on visual impairment. Invest Ophthalmol Vis Sci. 2011 Nov 11;52(12):8799-805. Due acknowledgment of Investigative Ophthalmology and Visual Science's permission and ownership of copyright in the work will be made in my thesis. If you are agreeable to the use of Investigative Ophthalmology and Visual Science's copyright in the work in my thesis, I would be grateful if you could reply to me at your earliest convenience. Thank you. Yours sincerely, Yingfeng Zheng Department of Ophthalmology Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road NUHS Tower Block, Level 11, Singapore 119228 Email: yingfengzheng@gmail.com Yingfeng Zheng Request for Permission to Reproduce Copyright Work Debbie Chin Tue, May 7, 2013 at 10:44 PM To: Yingfeng Zheng Dear Dr. Zheng, Permission is hereby granted to include the following article in your thesis for the National University of Singapore: Zheng Y, Cheng C-Y, Lamoureux EL, Chiang PPC, Rahman Anuar A, Wang JJ, Mitchell P, Saw S-M, Wong TY. How Much Eye Care Services Do Asian Populations Need? Projection from the Singapore Epidemiology of Eye Disease (SEED) Study. Invest Ophthalmol Vis Sci. 2013;54:2171-2177. A reprint of this material must include a full article citation and acknowledge ARVO as the copyright holder. Best regards, Debbie Chin ARVO Journals ________________________________________ From: yingfengzheng@gmail.com [yingfengzheng@gmail.com] on behalf of Yingfeng Zheng [yingfeng.zheng@gmail.com] Sent: Monday, May 06, 2013 10:30 PM To: Debbie Chin Subject: Request for Permission to Reproduce Copyright Work 07/05/2013 Debbie Chin Association for Research in Vision and Ophthalmology 12300 Twinbrook Parkway Suite 250 Rockville, Maryland 20852 United States Dear Debbie, Request for Permission to Reproduce Copyright Work I am a graduate student in the National University of Singapore ("NUS"), and am currently working on a thesis for submission to NUS as part of my academic program. My thesis is likely to be published electronically by NUS on the internet and on NUS' own intranet, and copies of my thesis will be made available to NUS and end users. My thesis aims to evaluate the social determinants of visual impairment and diabetic retinopathy in a multiethnic Asian population in Singapore. I am writing to seek your kind permission to use and reproduce, for purposes of submission, publication and distribution of my thesis as described above, the following works for which I understand Investigative Ophthalmology and Visual Science to be the copyright owner: The whole publication of: Zheng Y, Cheng CY, Lamoureux EL, Chiang PP, Rahman Anuar A, Wang JJ, Mitchell P, Saw SM, Wong TY. How Much Eye Care Services Do Asian Populations Need? Projection from the Singapore Epidemiology of Eye Disease (SEED) Study. Invest Ophthalmol Vis Sci. 2013 Mar 1;54(3):2171-7. Due acknowledgment of Investigative Ophthalmology and Visual Science's permission and ownership of copyright in the work will be made in my thesis. If you are agreeable to the use of Investigative Ophthalmology and Visual Science's copyright in the work in my thesis, I would be grateful if you could reply to me at your earliest convenience. Thank you. Yours sincerely, Yingfeng Zheng Department of Ophthalmology Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road NUHS Tower Block, Level 11, Singapore 119228 Email: yingfengzheng@gmail.com 2013-05-10 Prof Wong Tien Yin Head and Senior Consultants Department of Ophthalmology National University Hospital Dear Prof Wong, Request for Permission to Reproduce Copyright Work I am a graduate student in the National University of Singapore (“NUS”), and am currently working on a thesis for submission to NUS as part of my academic programme. My thesis is likely to be published electronically by NUS on the internet and on NUS’ own intranet, and copies of my thesis will be made available to NUS and end users. My thesis aims to evaluate the social determinants of visual impairment and diabetic retinopathy in a multiethnic Asian population in Singapore. I am writing to seek your kind permission to use and reproduce, for purposes of submission, publication and distribution of my thesis as described above, the following works for which I understand you to be the copyright owner: (a) The whole publication of Zheng Y, Lamoureux E, Chiang PPC, Anuar AR, Wong TY. Marital status and its relationship to the risk and pattern of visual impairment in Asians. J Public Health (Oxf). 2013 May 8. (b) The whole publication of Zheng Y, Lamoureux EL, Ikram MK, Mitchell P, Wang JJ, Younan C, Anuar AR, Tai ES, Wong TY. Impact of migration and acculturation on prevalence of type diabetes and related eye complications in Indians living in a newly urbanized society. PLoS One. 2012;7(4):e34829. Due acknowledgment of your permission and ownership of copyright in the work will be made in my thesis. If you are agreeable to the use of your copyright in the work in my thesis, I would be grateful if you could sign and return the duplicate of letter to me at your earliest convenience. A self addressed envelope is attached for your convenience. Yours sincerely, Yingfeng Zheng Department of Ophthalmology Yong Loo Lin School of Medicine, National University of Singapore, 1E Kent Ridge Road NUHS Tower Block, Level 11, Singapore 119228 Email: yingfengzheng@gmail.com Permission granted for the use requested above: I confirm that I am the copyright holder of the papers above and hereby grant you permission to use my copyright to the work described above in your thesis and for the purposes set out in this letter. Prof Wong Tien Yin Head and Senior Consultants Department of Ophthalmology National University Hospital Date: 2013-05-16 [...]... Socio-demographic and clinical characteristics of the participants 148 Associations of inadequate literacy with VI and poor VF 149 Associations of inadequate literacy with visual impairment and poor visual functioning, stratified by educational and income levels 150 Chapter VIII X VIII-1 Sociodemographic and clinical characteristics of the Indian participants 170 VIII-2 Oaxaca multivariate decomposition of. .. Relationships of social determinants with visual impairment 205 Appendix A1-1 A1-2 A5-1 A5-2 A5-3 A8-1 A8-2 Studies assessing the association of education level with visual impairment (VI) and eye disease in adult populations 208 Studies assessing the association of social determinant with utilization of eye care in adult populations 219 Area based socioeconomic measures: constructs and operational... 168 VIII-2 Proportion of presenting visual impairment among patients with diabetes stratified by English proficiency 169 Chapter IX IX-1 Prevalence of obesity, type-2 diabetes, diabetic retinopathy, and cataract in Indian Immigrants and local Malays living in Singapore 189 IX-2 Non-linear relationships of duration of residence with prevalence of type-2 diabetes and its related complications... number of people with visual impairment is still on the rise, driven by population aging and increasing prevalence of chronic systemic diseases (e.g., diabetes and hypertension).2;3 Secondly, there have been systematic differences in prevalence of eye disease and visual impairment among different social groups Whether it is in developing or developed countries, the burden of visual impairment is greater... inequalities?  How can the medical and non-medical systems be reformed to reduce health inequalities?  Finally, how relevant is the issue of health inequalities for Singapore? DEFINITION OF SOCIAL DETERMINANTS There are many methods that describe social determinants, and the terms such as social class, social stratum, social position and socioeconomic status are often used interchangeably, although... because they represent different social domains.29 Among them, education is the most widely documented social determinant for visual impairment: A higher level of education is consistently associated with higher odds of having visual impairment Despite its consistent association with visual impairment, the influences of education on common eye diseases such as diabetic retinopathy, age-related macular... cost of US$2,303 billion and an indirect cost of US$652 billion in production losses, informal care and deadweight welfare losses.67 It seems likely that eliminating avoidable visual impairment can result in a wide range of direct and indirect benefits at individual level (e.g., improvement in quality of life and reduction in risk of fall and co-morbidities), economic level (e.g., increasing rate of. .. [US] and . EPIDEMIOLOGY AND SOCIAL DETERMINANTS OF VISUAL IMPAIRMENT AND DIABETIC RETINOPATHY ZHENG YINGFENG (M.D.) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY. of PVI, BCVI, and visual function against age 147 Chapter VIII VIII-1 Proportion of diabetic retinopathy stratified by English proficiency 168 VIII-2. Proportion of presenting visual impairment. individual and group differences in health. Social determinants influence a wide range of systemic diseases (e.g., heart disease, diabetes), but the impacts of social determinants on visual impairment