Non-alcoholic fatty liver disease affects one in four people
in the general population in Europe and just over one in twenty people have
advanced liver fibrosis, a meta-analysis of 33 studies from 15 European
countries presented at the Digital International Liver Congress shows.
Non-alcoholic fatty liver disease (NAFLD) occurs when fat
accumulates in the liver. People with diabetes or metabolic syndrome have a
higher risk of developing non-alcoholic fatty liver disease. Fat accumulation
can lead to inflammation in the liver and damage (fibrosis). Liver damage due
to fat accumulation is called non-alcoholic steatohepatitis (NASH).
NAFLD is a growing public health
problem, but the prevalence is unclear. Studies have used differing methods to
diagnose NAFLD, employing either blood tests or imaging to diagnose the condition. A meta-analysis published by the Center for Disease Analysis in 2018, including general population studies from the largest European countries and the United States, estimated prevalence of between 25 and 30% in western Europe.
To assess the prevalence of NAFLD and NASH in Europe, researchers
from six European countries carried out a systematic review and meta-analysis
of studies published up to 2019. Studies were eligible for inclusion if they reported
prevalence in the general population but were excluded if they investigated prevalence
only in people with metabolic conditions or in children. Studies were also excluded
if they did not report data on alcohol consumption or if they failed to exclude
other causes of liver disease when calculating prevalence.
The research team identified 19 studies including 42,580 people
that diagnosed NAFLD by non-invasive imaging and nine studies including 84,235
people that assessed NAFLD prevalence by blood tests using the Fatty Liver Index.
Twelve studies reported on the prevalence of NASH (4696 participants) and five
on the prevalence of advanced fibrosis (7270 participants).
The cohorts were diverse, with wide variations in the
prevalence of obesity, type 2 diabetes and metabolic syndrome. They also
reported wide variations in the prevalence of NAFLD, ranging from 10.4% in a
Swedish study of 1015 people with a median age of 57 years and a diabetes
prevalence of 7%, to 48% in a study carried out in Italy (890 people) (median
age 53 years and diabetes prevalence 19%).
A meta-analysis of NAFLD prevalence studies found a pooled prevalence
of 27%, with no difference in the final result between studies which used imaging
or blood tests to assess prevalence.
Studies assessing the prevalence of NASH were inevitably
biased due to referral for biopsy on the basis of clinical indication. The
12 studies found that 64% of 4696 NAFLD patients referred for biopsy had
Meta-analysis of five studies of advanced fibrosis
prevalence in the general population found a prevalence of 6%. These studies used blood tests to assess the prevalence of F3 or f4 fibrosis (advanced fibrosis or cirrhosis).
The study authors say this the largest analysis to date of
the burden of NAFLD in Europe and needs to be followed up by an economic
analysis of the potential benefits of non-invasive testing for advanced fibrosis
in the general population, given the high prevalence detected across studies
included in this meta-analysis.