Nonlinear relationship between serum uric acid and body mass index: a cross-sectional study of a general population in coastal China

BACKGROUND: Conflicting evidence exists on the relationship between body mass index (BMI) and serum uric acid (SUA). Therefore, we aimed to evaluate the SUA–BMI relationship in a large-scale epidemiological survey in coastal China. METHODS: This survey was conducted among the general population in the coastal region of China from September 2014 to January 2015. SUA Levels were measured by the automatic Sysmex Chemix-180 biochemical analyzer. RESULTS: A total of 6098 men (BMI: 24.58 ± 3.74 kg/m(2)) and 7941 women (24.56 ± 3.64 kg/m(2)) were included in this study. A stronger positive BMI-SUA association was found for men than women (all P-values < 0.05). The piecewise linear spline models indicated a U-shaped relationship of SUA-BMI association for both men and women; and the lowest turning points were at 19.12 kg/m(2) for men and 21.3 kg/m(2) for women. When BMIs were lower than the nadir point, each 1 kg/m(2) increase in BMI related to a 7.74-fold (95% CI − 14.73, − 0.75) reduction for men and 2.70-fold reduction (− 4.47, − 0.94) for women in SUA levels. Once the BMI was higher than the nadir point, each 1 kg/m(2) increase in BMI was related to a 5.10-fold (4.44, 5.77) increment for men and 3.93-fold increment (3.42, 4.43) for women in SUA levels. The regression coefficient differences between the two stages were 12.84 (5.66, 20.03) for men and 6.63 (4.65, 8.61) for women. CONCLUSIONS: A U-shaped relationship between BMI and SUA was found for both men and women; the association was stronger for men than women.