LAUSR

Ophthalmic epidemiology has benefited from large, longitudinal, population-based studies of eye health from multiple countries in the past 30 to 40 years, including the Singapore Epidemiology of Eye Diseases (SEED) study. Well-conducted cross-sectional studies have been invaluable in globally mapping the burden of eye disease. The Global Burden of Disease Vision Loss Expert Group has made use of more than 200 data sets for this purpose,1 although some regions— Central Africa, Central and Eastern Europe, the Caribbean, and Latin America—are underrepresented in this body of research. Patient-reported outcome measures are well developed in ophthalmology, provide the tools to gain the patient’s perspective, and ultimately inform the development of patientcentered models of care. In this issue of JAMA Ophthalmology, Fenwick and colleagues2 report independent associations between ethnicity and patient-reported vision-specific functioning (as determined with use of the VF-11, a Rasch analysis– modified version of the VF-14 questionnaire3) in patients with late age-related macular degeneration (AMD) in the SEED study. The VF-11 questionnaire asks respondents about difficulty in functioning across a range of common activities. Although this questionnaire needs to be adapted for local context (eg, removing questions about driving for Singaporeans, where car ownership is very low), it has been widely used internationally and is considered sensitive to measuring the effects of late, but not early, AMD.4 The central finding of the study by Fenwick and colleagues is that (keeping other factors equal in multivariate models that included sociodemographic factors, ocular and systemic comorbidities, and visual acuity) scores on the VF-11 were 19.1% worse in the Chinese patients (P < .001); were 13.5% worse in the Malay patients, although the results were not statistically significant (P = .07); and were unchanged in the Indian patients (P = .68) among those with late AMD compared with those without AMD. Previous investigations3 into the validity of the VF-14 questionnaire included testing differential item functioning (DIF) to determine whether different groups within the same sample, despite an equal level of functioning, respond differently to individual items. Cultural DIF was found between Singaporean Malays and Western populations, but there was no DIF for age, sex, type of eye disease, degree of visual impairment, and comorbidities. This cultural DIF was limited to just 1 item on the VF-14—“recognizing friends.”3 Fenwick and colleagues2 suggest that the VF-11, because of its psychometric features, performs differently across ethnicities, which is an interesting and novel finding. The SEED study, because it comprises 3 cross-sectional studies involving approximately 10 000 Chinese, Malay, and Indian participants, is an ideal opportunity to investigate the effects of ethnicity on patient-reported health outcomes. Nevertheless, a study that uses other research methods is needed to illuminate the mechanisms behind this ethnic difference in reporting visual function. Although this finding is of considerable interest, it remains unclear how it can be translated into better AMD care for the multiethnic patient population in Singapore. The patient’s perspective is important to meeting health care needs in an era of patient-centered care. However, if self-reporting of visual function varies by ethnicity, it lends uncertainty to how accurately visual function is being reported. Differences might be explained by cultural variations in communication style or biases against reporting difficulties in daily life. Either way, differences in self-report between ethnic groups is relevant to the broader challenge of health literacy, in which accurate communication with patients is critical. Canadian researchers5 have found that older people are the most health illiterate and that low health literacy can negatively affect health outcomes. Such findings are particularly pertinent to ophthalmologists who manage chronic illnesses, such as AMD, in older patients. Further research is needed to explain ethnic differences in reporting visual functioning. Methodological considerations are important, such as whether research surveys are self-administered, available in the preferred language of the respondents, or delivered as an interview during which there is an opportunity to confirm understanding of the questions and answers. The feasibility of self-reporting has been investigated using the Think Aloud method,6 which revealed that most people comprehend concepts of capability. This method could be used to examine how different ethnic groups respond to a survey tool designed to measure visual function. Exploration of ethnic differences in patient-reported difficulty in visual functioning is relevant not only to care in Singapore but also in other communities with multiethnic and multicultural populations. Cultural competence is a broad concept that relates to efforts to improve the accessibility and effectiveness of health care for ethnic or minority groups. Future work that builds on the findings of this study by Fenwick et al2 may explore the broader issues of impact of disease and patterns in timely access to care across ethnic groups so critical to achieving optimal outcomes in chronic eye diseases. Related article Ethnic Differences in Self-reported Visual Function Among Patients With AMD Invited Commentary