Hypertension and risk of cholangiocarcinoma: a systematic review and meta-analysis

Background: Hypertension has been demonstrated to enhance the risk of cholangiocarcinoma (CCC) by several researches, which, however, still remains controversial. To this end, a systematic review and metaanalysis was performed to further investigate the association between hypertension and CCC risk. Methods: We searched PubMed, EMBASE, ISI Web of Science to collect relevant researches published before November 2017. Afterwards, random effects model proposed by DerSimonian and Laird was employed to determine the correlation between hypertension and CCC risk. Results: Nine articles, comprising 2,016 patients with CCC and 199,812 healthy controls, were finally enrolled in our study. Our findings failed to support the correlation between hypertension and elevated risk of CCC among these heterogeneous studies [summary odds ratio (OR), 0.87; 95% confidence interval (CI), 0.57-1.17; I-2= 79.5%]. In subgroup analysis following separation of intrahepatic cholangiocarcinoma (ICC) and extrahepatic cholangiocarcinoma (ECC), hypertension also failed to harbor a correlation with elevated risk of ECC (OR, 0.74; 95% CI, 0.42-1.37) and ICC (OR, 1.07; 95% CI, 0.43-1.71). Conclusions: Hypertension did not harbor any correlation with elevated risk of CCC.