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Title: The National Eye Survey of Trinidad and Tobago
Author: Braithwaite, Tasanee
ISNI:       0000 0004 7966 4239
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2019
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Background: Avoidable vision impairment (VI, Snellen acuity <6/12) is a global public health concern. There were no data on the prevalence, causes, or risk factors associated with VI in Trinidad and Tobago, and only limited data within the Caribbean region. The societal cost of VI and the impact on quality of life was unknown. Study design: A national, population-based, cross-sectional survey of the non-institutionalized population aged 40 years and above in Trinidad and Tobago in 2013/2014, used random multistage cluster sampling with probability proportional to size methods. Methods: In each of 120 clusters, 35 eligible adults were enumerated. In community screening, the presenting uniocular distance and binocular near visual acuity was measured and basic demographic, socioeconomic and health data collected. All participants were invited to regional clinics for more detailed interview and comprehensive ocular and medical examination with imaging. Interviews included assessment of health service utilization, costs, and health-related quality of life, using the EQ-5D instrument. Results: From 3556 households, 4263 eligible adults were identified, of whom 84.2% (n=3589) participated in community screening, and 65.4% (n=2790) in regional clinics. After adjustment for the multilevel, clustered study design and non-response rate, and weighting by the age, sex and municipality of participants, the prevalence of presenting VI was 11.88 % (95% confidence interval (CI) 10.88-12.97, n = 468 / 3580), including blindness in 0.73% (95% CI 0.48 to 0.97, n = 31). The leading causes of blindness were glaucoma (31.7% 95% CI 18.7 to 44.8), cataract (28.8%, 95 % CI 12.6 to 45.1), and diabetic retinopathy (19.1%, 95 % CI 4.2 to 34.0). The leading cause of presenting distance VI was uncorrected refractive error (47.4%, 95% CI 43.4 to 51.3), and 86.1% (95% CI 82.88-88.81) of distance VI was potentially avoidable. A further 22.3% (95% CI 20.7 to 23.8) had uncorrected near VI resulting from presbyopia. In total, within Trinidad and Tobago there were an estimated 185,273 (95% CI 167,337 to 203,048) people aged 40 years and above with near or distance VI, and 176,323 cases were potentially avoidable. Significant independent associations with presenting distance VI included increasing age (p<0.0001), diagnosed diabetes (p=0.0004), and employment status (p=0.0002). Significant independent associations with presenting near VI included male sex (p<0.0001), no health insurance (p<0.0001) and employment status (p<0.0001). Presenting distance VI was significantly associated with the odds of reporting reduced health-related quality of life (p=0.004), after adjustment for independent predictors including older age, female sex, multiple co-morbidities, lack of health insurance, education level and marital status. An estimated 762 quality adjusted life years were lost from VI per 100,000 population in 2014. VI was associated with a total economic cost to society of TT$3,842,324,655 (UK£365,650,241), of which 73.3% resulted from loss of wellbeing. Excluding intangible effects, indirect costs accounted for 70.5% (TT$722,379,355) of the remaining total cost, direct medical costs for 17.9% (TT$183,303,734) and direct non-medical costs for 11.6% (TT$19,362,310) Conclusions: The National Eye Survey of Trinidad and Tobago obtained original population-based data on the magnitude, causes and risk factors for avoidable VI in Trinidad and Tobago, and identified significant associated economic and quality of life impact. This evidence-base provides the foundation for the development of a national eye care strategy.
Supervisor: Gray, Alastair ; Bourne, Rupert Sponsor: Fight for Sight
Qualification Name: Thesis (M.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Health economics ; Biostatistics ; Epidemiology ; Ophthalmology ; Vision disorders ; Medicine ; Population