Overview
Diabetic retinopathy (DR) remains a leading cause of vision impairment worldwide, closely tied to diabetes prevalence and disease management. A recent cross-sectional analysis leveraging NHANES data from 1999 to 2020 explores whether a socioeconomic indicator—the family income to poverty ratio (PIR)—is associated with DR prevalence among U.S. adults aged 20 and older. The study’s central finding is a negative association: higher PIR corresponds to a lower likelihood of reporting DR, even after adjusting for a broad range of demographic, metabolic, and clinical factors.
What PIR measures and why it matters
PIR is NHANES’s measure of household income adjusted for family size and poverty guidelines. This index captures relative economic resources, making it a practical proxy for access to care, health literacy, and the ability to manage chronic conditions. Because DR risk rises with poor glucose control, hypertension, and longer diabetes duration, PIR’s link to access and adherence may partly explain its association with DR prevalence.
Key findings from the NHANES analysis
The study analyzed 39,210 adults, with 31,907 in the PIR < 5 group and 7,303 in the PIR ≥ 5 group. DR prevalence was 2.7% in the lower-PIR group but only 1.5% in the higher-PIR group. After controlling for age, sex, race, education, BMI, waist circumference, smoking, diabetes duration, insulin use, HbA1c, albumin, blood pressure, total cholesterol, and HDL-C, PIR remained negatively associated with DR (OR 0.91; 95% CI, 0.86–0.97; p = 0.002).
Subgroup analyses highlighted that non-Hispanic White individuals benefited most from higher PIR (OR 0.87; 95% CI, 0.80–0.96; p = 0.005; interaction p = 0.017). An ROC analysis incorporating age showed moderate discriminative performance for predicting DR (AUC 0.747), suggesting PIR adds explanatory value beyond traditional risk factors.
Implications for screening and public health
The inverse relationship between PIR and DR prevalence implies that income-related access to care and health behaviors influence DR risk. Higher-income groups tend to have better access to eye care, earlier diabetes screening, and better treatment adherence, all of which can reduce DR risk. The study’s authors advocate targeted DR screening and preventive efforts for low-income populations to mitigate social burdens and vision loss, emphasizing that PIR can serve as a practical indicator in health planning.
Clinical and policy considerations
From a clinical standpoint, screening guidelines could consider socioeconomic indicators alongside medical risk factors to prioritize outreach. Public health strategies might include expanding affordable eye examinations, diabetes education, and barriers-reducing interventions in low-PIR communities. While PIR is not a causal measure, its association with DR prevalence underscores the broader impact of social determinants on eye health.
Limitations and future directions
The cross-sectional design limits causal inference. NHANES data rely on self-reported DR diagnosis in many cases, which may introduce misclassification bias. Furthermore, PIR was categorized with PIR ≥ 5 treated as 5 for disclosure purposes, and the study could not distinguish between type 1 and type 2 diabetes in relation to DR. Future longitudinal studies should confirm causality and examine how changes in PIR over time relate to DR incidence and progression.
Conclusion
This NHANES-based analysis demonstrates a meaningful negative association between family income to poverty ratio and DR prevalence among U.S. adults. The results reinforce the role of social determinants in chronic disease complications and point toward PIR as a potential tool for risk stratification and targeted screening in low-income populations.
