Figure 2.

Subgroup analysis of the association between serum leptin levels and breast cancer in different countries. Zero is not included in this confidence interval, which indicates that the relationship between leptin levels and breast cancer is different between the case and control groups. The positive SMD value suggests that the mean circulating leptin level in the case group is higher than that in the control group in Asian and Caucasians, while the negative SMD value indicates that the mean leptin level in the case group is lower than that in the control group in Africans.