Metabolic syndrome and liver-related events: a systematic review and meta-analysis

Previous studies have suggested that metabolic syndrome (MetS) and its component conditions are linked to the development of many benign or malignant diseases. Some studies have described relationships among metabolic syndrome or diabetes and liver cancer, but not many articles described the relationships between MetS and cirrhosis, acute hepatic failure, end-stage liver disease, and even death. However, liver cancers, cirrhosis, acute hepatic failure, end-stage liver disease, and liver-related mortality-collectively described as liver-related events (LREs)-may have different relationships with MetS. We undertook this meta-analysis to examine the association between MetS and LREs, and to determine whether geographic region or hepatitis B virus (HBV) positivity might influence the association.

Relevant studies were identified from PubMed, EMBASE, and the Cochrane database. Two reviewers independently searched records from January 1980 to December 2017. The search terms included 'metabolic syndrome', 'diabetes mellitus', 'insulin resistance syndrome', and 'metabolic abnormalities', combined with 'cirrhosis', 'hepatic fibrosis ', 'hepatocellular carcinoma', 'complication', 'LRE', 'HCC', 'liver-related events', and 'liver cancer'. No language restriction was applied to the search. We chose the studies reporting an association between MetS and LREs. We used Begg's and Egger's tests and visually examined a funnel plot to assess publication bias. All analyses were conducted in Stata 14.0 software.

There were 19 studies (18 cohort and 1 case-control) included in the analysis, with a total of 1,561,457 participants. The subjects' ages ranged from 18 to 84 years. The combined analysis showed an overall 86% increase risk of LREs in cases with MetS (RR: 1.86,95% CI: 1.56-2.23). The funnel plot was asymmetrical, and the Egger's test p values showed a publication bias in this meta analysis. However, through the trim and fill method, we obtained a new RR value for LREs with MetS of 1.49 (95% CI: 1.40-1.58, p = 0.000). There was no obvious difference with the two answers, so we concluded that the results were robust. For hepatitis B positive patients, the RR for MetS and LREs was 2.15 (95% CI:1.02-4.53, p = 0.038), but for the hepatitis B negative patients, the RR was 1.85 (95% CI:1.53-2.24, p = 0.000). And for non-Asians, the RR for MetS and LREs was 2.21 (95% CI: 1.66-2.69, p = 0.000), while for Asians, the RR was 1.73 (95% CI: 1.35-2.22, p = 0.000).

This meta-analysis showed that MetS is associated with a moderately increased risk of LREs prevalence. Patients with MetS together with hepatitis B are more likely to develop hepatic events. For non-Asians, MetS is more likely to increase the incidence of LREs.