C3 and Abdominal obesity: As shown in Table 3, abdominal obesity was significantly associated with immunoglobulin E [crude OR (95% CI) 0.987 (0.976–0.997); adjusted OR (95% CI) 0.987 (0.977–0.998); P < 0.05 for all] and complement C3 levels [crude OR (95% CI) 1.018 (1.011–1.026); adjusted OR (95% CI) 1.018 (1.010–1.025); P < 0.05 for all].