The pooling of data from many independent studies on one subject, with analysis of the collected data to determine overall trends, is called a meta analysis. A recent meta analysis on the topic of non-alcoholic fatty liver disease (NAFLD) reinforces the finding that the disease is associated with an increased risk of heart failure within a decade.
NAFLD is one of the most common causes of chronic liver disease worldwide, affecting up to 30 percent of adults. Due to the increasing incidence and prevalence of overweight and obesity, non-alcoholic fatty liver disease is also expected to increase sharply over the next decade.
Recently published studies have implicated NAFLD in the development of heart failure — a condition in which the heart is unable to pump adequate quantities of blood throughout the body. The degree to which non-alcoholic fatty liver disease increases the risk of heart failure has not been determined, nor has it been determined whether this risk differs according to the severity of liver disease.
The researchers sought to determine these unknowns. They pooled the data of 11 international, observational, published studies, the most recent in March 2022. The studies included more than 11 million participants. Pooled data analysis of the results of all 11 studies showed that the presence of NAFLD was associated with a 50 percent increased risk of developing heart failure over a decade.
The risk also increased as a function of the severity of NAFLD, especially with extensive liver fibrosis (scarring), when the risk of heart failure was 76 percent. This finding, however, was based on the data from only 2 studies.
It is not known precisely how non-alcoholic fatty liver disease increases the risk of developing heart failure, say the researchers. They speculate that some mechanisms involved may be that the NAFLD worsens systemic insulin resistance or releases inflammatory and blood-thickening chemicals.
The researchers acknowledge that there are limitations to their meta analysis, the greatest being the observational nature of the included studies, which eliminates establishing a cause and effect relationship. They advise careful monitoring for heart failure in all patients with NAFLD.