Study Supports Using Ethnicity-Based Strategies for Delaying the Onset or Progression of AMD

The influence of ethnicity on the association between age-related macular degeneration (AMD) and vision has been unclear. However, a recently published analysis of data from 3 population-based studies in 3 ethnic groups supports the use of ethnicity-based strategies for delaying the onset or progression of AMD.

Eva Fenwick, PhD (pictured) and colleagues from the Singapore Eye Research Institute at the Singapore National Eye Centre in Singapore randomly sampled participants from 40—80 years of age in the cross-sectional, population-based Singapore Epidemiology of Eye Diseases (SEED) study. The SEED study included a series of 3 studies, each with adult participants from a specific ethnic group:

The first study was done in Malays, the second in Indians, and the third in Chinese.

Of the 10,033 baseline SEED study participants selected who agreed to participate in the team’s current study, 9962 had both gradable fundus images and Visual Function Index data. These images and data enabled the team to grade AMD as early or late and determine the association between AMD by stage and vision-specific functioning (VSF) in each ethnic group.

Early AMD was present in 590 (5.9%) and late AMD in 60 (0.6%). The mean age of the study participants was 58.5 years (standard deviation, 10.4 yr), and approximately half of the study population was male.

The team collected VSF data by obtaining scores on the VF-11 questionnaire, which measured the degree to which vision loss impaired basic functions such as the ability to read a newspaper or a medication label. Researchers then used Rasch analysis to convert these VF-11 scores to estimated interval measures of VSF.

They also measured the subjects’ uniocular distance visual acuity by using the logMAR chart. In addition, the team graded the subjects’ fundus photographs by using a modified Wisconsin Age-Related Maculopathy Grading System. Data were collected between January 20, 2004, and December 19, 2011, and analyzed between November 12, 2015, and December 28, 2016.

The team used differenr multiple linear regression models to examine the association between AMD and VSF in the 3 ethnic groups. They adjusted the data for age, sex, presenting visual acuity in the better-seeing eye, education level, income, smoking status, hypertension, diabetes, cardiovascular disease, total cholesterol level, and other eye conditions.

In the adjusted models, compared with no AMD, early AMD was associated with a small (3%) reduction in VSF in the Chinese group (β = −0.12; 95% confidence interval (CI), −0.23 to 0.00; P = 0.046) but not in the other ethnic groups. In addition, Chinese with late AMD had a highly statistically significant 19% loss of VSF (β = −0.78, CI, −1.13 to −0.43; P < 0.001), which the investigators also categorized as “clinically significant.”

In contrast, no association between late AMD and VSF was found in the Indian group (P = 0.68). However, in Malay participants, the investigators found a trend toward worse VSF with increasing AMD severity: Malays with late AMD had a 13.5% loss of VSF (β = −0.49, CI, −1.01 to 0.04; P = 0.07).

Based on these findings, the investigators concluded that early and late AMD negatively affected VSF in Chinese, but not in Indian or Malay participants, which suggested the independent operation of an ethnic influence on the association of AMD with VSF in multiethnic Asian populations. As a result, according to the team, “Culturally sensitive interventions to improve VSF for Chinese and Malay people with AMD may be warranted.”

In an accompanying editorial, Lisa Keay, PhD, MPH, BOptom, noted that, although obtaining the patient’s perspective is important for ensuring patient-centered care, variation in self-reporting of visual function by ethnicity makes the accuracy of these reports questionable. She urged further research to explain these ethnic differences and to explore the impact of disease and patterns of timely access to care by ethnic group.

A report on the study, “Ethnic differences in the association between age-related macular degeneration and vision-specific functioning,” and the accompanying editorial, “Ethnic differences in self-reported visual function among patients with age-related macular degeneration: Implications for care,” appear in the March 30, 2017, issue of JAMA Ophthalmology.

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