Importance: Understanding the link between ethnicity and health is critical to making appropriate public policy decisions. Few population-level data are available about this connection, however, including the influence of ethnicity on the association between age-related macular degeneration (AMD) and vision-specific functioning (VSF).
Objective: To identify the influence of ethnicity on VSF among Chinese, Malay, and Indian patients with AMD.
Design, setting, and participants: This cross-sectional, population-based study relied on patients and their data from 3 population-based studies in 3 ethnic groups: Chinese, Malay and Indian. Of 10 033 Chinese, Malay, and Indian adults who participated in the study, 9962 (99.3%) who had gradable fundus images and Visual Function Index (VF-11) data available were included in the analyses for the present study. Uniocular presenting distance visual acuity was measured using the logMAR chart. Separate multiple linear regression models examined the association between AMD and VSF in the 3 ethnic groups, adjusting for age, sex, presenting visual acuity in the better-seeing eye, educational level, income, smoking status, hypertension, diabetes, cardiovascular disease, total cholesterol level, and other eye conditions. Data were collected between January 20, 2004, and December 19, 2011; data analysis was conducted between November 12, 2015, and December 28, 2016.
Exposures: Age-related macular degeneration according to fundus photographs graded using a modified Wisconsin Age-Related Maculopathy Grading System.
Main outcomes and measures: Rasch analysis was used to convert VF-11 questionnaire scores to estimated interval measures of VSF.
Results: Of the 9962 participants, the mean (SD) age was 58.8 (10.4) years; 4909 (49.3%) were male; 590 (5.9%) had early AMD (241 Chinese, 161 Malays, and 188 Indians) and 60 (0.6%) had late AMD (25 Chinese, 21 Malays, and 14 Indians). In the adjusted models, compared with no AMD, early AMD was associated with a small reduction in VSF (2.9%; β = -0.12; 95% CI, -0.23 to -0.00; P = .046) in the Chinese group but not in the Indian and Malay groups. Moreover, Chinese participants with late AMD had a clinically significant 19.1% loss of VSF (β = -0.78; 95% CI, -1.13 to -0.43, P < .001). In the Malay group, those with late AMD had a 13.5% drop in VSF (β = -0.49; 95% CI, -1.01 to 0.04; P = .07) compared with their counterparts without AMD. Similarly, late AMD was not associated with VSF in the Indian group.
Conclusions and relevance: Early and late AMD negatively affected VSF in Chinese but not in Indian and Malay participants. This finding suggests that there is an independent ethnic influence in the association of the disease with VSF in multiethnic Asian populations, thus warranting ethnicity-based strategies to delay the onset or progression of AMD.