RETN and Hypertension: Further, subgroup analysis by sample size indicated that the association between serum resistin level and hypertension were more prominent in the large sample size studies (total study size over 100, SMD = 1.87, 95% CI: 0.16–3.59, P = 0.03) than in the small size studies (total study size less than 100, SMD = 0.40, 95% CI: −0.10–0.90, P = 0.12) (Figure 4).