INTRODUCTION
Over the last decade non-alcoholic fatty liver disease (NAFLD) has
become the most common chronic liver disease (CLD) in Western world.
This liver disease is a clinical syndrome which consists of several
liver disorders. It is defined by existence of steatosis in at least 5%
of hepatocytes with no history of alcohol consumption or evidence of
other CLD. The clinical-histologic phenotype of the disorder extends
from benign non-alcoholic fatty liver (NAFL) to more severe
non-alcoholic steatohepatitis (NASH). NASH is more progressive form that
can lead to fibrosis and cirrhosis which consequently lead to liver
transplantation or progress to hepatocellular carcinoma (HCC) (1-4)
Today, NAFLD is acknowledged as a liver manifestation of metabolic
syndrome (MetS). With NAFLD being part of MetS, it can be closely
associated with unhealthy lifestyle. Studies have shown that changes in
unhealthy lifestyle improve transaminase levels and NAFLD (5).
One of the most popular beverages in the world is coffee. Inarguably,
drinking coffee is a cultural phenomenon with billions of cups consumed
worldwide. In recent years, a lot of interest has been tempted in the
overall beneficial effects regarding the coffee consumption in reducing
total and cause specific morbidity and mortality. Coffee seems to
benefit health in general, especially liver health (6-10).
Some authors have published data
about beneficial effects of coffee consumption in diabetes mellitus (7),
while some other reported its usefulness in the context of fibrosis,
cirrhosis, and HCC in chronic hepatitis C infected patients (8). Due to
epidemic increase of type 2 diabetes mellitus (T2DM), obesity and MetS,
around 25% of population has fatty liver disease. NAFLD is not only
important due to liver-related complications (i.e. cirrhosis and HCC)
but also it is important in the context of multisystem disease that is
associated with cardiovascular diseases, chronic kidney disease and
T2DM, as well as to some other chronic diseases. Therefore, the
beneficial effect of coffee consumption could be of great clinical
interest because coffee is easily available. Although according to
meta-analysis by Shen H et al (9) about the beneficial effect of coffee
consumption on progression of liver disease, its effect in NAFLD
population is not unequivocally clear.
Poor health outcomes are also associated with inadequate sleep. Insomnia
and short sleep duration have been linked with obesity, diabetes,
hypertension, cardiovascular diseases, and depression. Mechanism of it
lies in irregular habits in exercise and diet, decreased leptin, and
modulation of hormones of hypothalamic-pituitary-adrenal system (11,12).
Some reports had shown that short sleep duration was associated with
NAFLD prevalence, while some other studies reported that that long sleep
duration related to incident NAFLD (11-13). Thus, the relationship
between NAFLD and sleep duration is still poorly defined.
Finally, cigarette smoking is an unhealthy habit that is associated with
many diseases on numerous organs. This habit damages the antioxidant
system which can have repercussions on numerous organs. Smoking is an
acknowledged risk factor for developing MetS, which is risk factor for
NAFLD development (16-18). It has been reported that smoking can
increase the risk for fibrosis and cirrhosis in patients with viral
hepatitis, but only a few studies have investigated the relationship
between smoking and NAFLD (16-18).
According to this observations,
our aim was to explore the association between coffee consumption, sleep
duration and smoking status and the controlled attenuation parameter
(CAP) and liver stiffness measurements (LSM) as the surrogate markers of
liver steatosis and fibrosis in a large cohort of NAFLD patients in
Mediterranean parts of Croatia.