Relative Fat Mass Associated with Hyperuricemia in Adults: A Cross-Sectional Study

Aims: There is a close relationship between obesity and hyperuricemia. Relative Fat Mass (RFM) is considered a new indicator for evaluating obesity. We aim to explore the relationship between RFM and the risk of hyperuricemia in adults.

Methods: This cross-sectional study included adult participants from the 2007-2018 National Health and Nutrition Examination Survey (NHANES). The RFM was calculated as: RFM =64 - (20 × height/waist circumference) + (12 × sex), where sex is defined as 0 for men and 1 for women. Hyperuricemia was confirmed by using serum uric acid (SUA) levels ≥ 7 mg/dL in men and ≥ 6 mg/dL in women. The relationship between RFM and the risk of hyperuricemia was thoroughly investigated.

Results: A total of 29369 participants were enrolled in this study. The RFM levels in the hyperuricemia group were higher than those in the non-hyperuricemia group (P < 0.01). Logistic and linear regression indicated that RFM levels were positively associated with the risk of hyperuricemia (OR=1.08, 95% CI: 1.05-1.11, P < 0.001) and SUA levels (β=0.04, 95% CI: 0.03-0.05, P < 0.001). The relationship remained consistent across subgroups. Smooth curve fitting showed a nonlinear relationship, with an inflection point at 34.22. Above this threshold, the link between RFM levels and hyperuricemia was found to be more remarkable.

Conclusion: Higher RFM is associated with an increased risk of hyperuricemia. RFM could act as a cost-efficient and straightforward measure for hyperuricemia risk assessment.