Weight-Adjusted Waist Index Successfully Predicts Macular Degeneration

A recent cross-sectional study has identified a significant positive correlation between weight-adjusted waist index and risk of age-related macular degeneration (AMD).

The study, conducted in Fujian, China, collated data from the National Health and Nutrition Examination Survey (NHANES) in order to establish the weight-adjusted waist index's predictive capabilities for AMD and its potential superiority to existing measures such as body mass index (BMI).

“The research underscores the potential of the [index] as a reliable predictive biomarker for AMD, with spline smoothing analyses confirming a non-linear positive relationship between the [index] and AMD prevalence,” writes Yuting Wu, Department of Ophthalmology, Affiliated People’s Hospital, and colleagues.1

The team pulled data on 20,497 participants from NHANES from 2005 to 2008; after excluding participants younger than 40 years, those with missing data on waist circumference (WC) or weight, and those missing other relevant data, the study was narrowed down to 5132 participants. Among the population, 50.16% of participants were female and 49.84% were male.1

Individuals within the 2005-2008 NHANES cycle underwent retinal photography. AMD was diagnosed based on distinctive characteristics of the fundus, going by standard classification.1

Weight-adjusted waist index measurements were calculated by dividing WC by the square root of weight in kilograms. Data were then categorized into tertiles; Tertile 1 (8.59-10.85), Tertile 2 (10.85-11.52), and Tertile 3 (11.52-15.70). Tertile 3 exhibited a substantially greater risk of AMD, measured at 1.9 times greater than Tertile 1 (odds ratio [OR], 2.90, 95% CI 2.18-3.86; P <.0001). Higher proportions of weight, BMI, and WC were connected to higher weight-adjusted waist index tertiles, as well as a higher likelihood of diabetes, hypertension, and AMD.1

The study revealed that each individual unit increase in the index raised that participant’s chances of having AMD by as high as 76%. Threshold effect analyses highlighted a turning point of around 12.11 in the general population. Below this threshold, a substantial positive increase was observed in AMD (OR 1.50, 95% CI, 1.04-2.16; P =.0300). Above it, there was no significant increase in AMD (OR 0.75, 95% CI, 0.39-1.45; P =.3943).1

The predictive capacity of the index for AMD was tested through receiver operating characteristic (ROC) curve analysis. Results were compared against other commonly used obesity assessment indicators. To measure AMD incidence reporting, the team utilized area under the curve (AUC) values: weight-adjusted waist index, 0.625; weight, 0.560; BMI, 0.530; and WC, 0.508.1

Coupled with a positive association between the weight-adjusted waist index and risk of AMD (OR = 1.76 1.52, 2.04; p <0.0001), these findings indicate that the index has a substantially greater ability to indicate AMD risk when compared to WC, weight, and BMI. Wu and colleagues suggest that the index is therefore a more reliable indicator of potential AMD in adults aged ≥40 years.1

While BMI data is simpler to collect, its diagnostic performance can decrease with an individual’s age, with difficulty distinguishing between fat and muscle mass. A given BMI cutoff has been shown to miss more than half of people with excess fat.2

Wu and colleagues noted that the utilization of BMI as an indicator of AMD and other obesity-related diseases has resulted in the “obesity paradox”, which suggests that individuals with obesity may have more positive prognoses than the average-weight population. However, they indicate that the weight-adjusted waist index is more capable of accounting for both adipose tissue and subcutaneous fat, which are occasionally missed by other tests.1

“These findings emphasize the significance of early prediction and intervention for AMD in the general population,” writes Wu and colleagues. “Nonetheless, future research should prioritize investigating diverse racial groups, conducting longitudinal studies to establish cause-and-effect relationships, and potentially utilizing intelligent ophthalmology (IO) technology to explore molecular mechanisms in greater depth, as the pathophysiology of AMD warrants further exploration.”1

References

1. Wu Y, Liu Y, Jiao Z, et al. Association between the weight-adjusted waist index and age-related macular degeneration in US adults aged≥40 years: The NHANES 2005–2008. Frontiers in Medicine. 2025;12. doi:10.3389/fmed.2025.1552978

2. Romero-Corral A, Somers VK, Sierra-Johnson J, et al. Accuracy of body mass index in diagnosing obesity in the adult general population. International Journal of Obesity. 2008;32(6):959-966. doi:10.1038/ijo.2008.11