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A higher weight-adjusted waist index (WWI) was associated with an increased prevalence of age-related macular degeneration (AMD) in US adults aged 40 years and older, according to a study published in Frontiers in Medicine.

“The research underscores the potential of the WWI as a reliable predictive biomarker for AMD, with spline smoothing analyses confirming a non-linear positive relationship between the WWI and AMD prevalence,” the study team wrote.

The WWI, calculated by dividing waist circumference in centimeters by the square root of body weight in kilograms, is a novel index that assesses central obesity. It has emerged as a predictor of cardiometabolic risk in several studies and has become a vital parameter in ocular disease, researchers explained.

The study investigated the potential association between WWI and AMD in 5,132 participants aged 40 and older engaged in the National Health and Nutrition Examination Survey between 2005 and 2008. Researchers based AMD diagnosis on fundus photography using a standard classification system.

WWI Can Increase Likelihood of AMD By 76%

In total, AMD affected 391 participants, or 7.62% of the study sample. Participants were divided into tertiles based on their WWI. Tertile 1 consisted of WWI values between 8.59 and 10.85; Tertile 2 consisted of values between 10.85 and 11.52; and Tertile 3 consisted of values between 11.52 and 15.70.

According to the study results, the WWI was significantly associated with AMD risk. Each unit increase in WWI boosted the likelihood of having AMD by 76% in one model. When researchers compared tertiles, participants in the highest WWI group had 1.9 times greater risk of developing AMD than those in the lowest tertile.

The positive association between the WWI and AMD remained stable across various populations in subgroup analyses and interaction tests.

When researchers performed receiver operating characteristic curve analysis to assess the predictive power of the WWI for AMD compared with other obesity assessment indicators, the WWI outperformed BMI, waist circumference, and weight in predicting AMD.

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