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Review Article
Non-alcoholic Fatty Liver Disease: A Clinical Update
Joseph M Pappachan*
1
, Shithu Babu
2
, Babu Krishnan
3
and Nishal C Ravindran
4
1
Department of Endocrinology, Diabetes & Metabolism, Royal Lancaster Infirmary, University Hospitals of Morecambe Bay NHS
Trust, Lancaster, UK;
2
Department of Medicine, Dorset County Hospital, Dorchester, UK;
3
Department of Gastroenterology &
Hepatology, Royal Bournemouth Hospital, Bournemouth, UK;
4
Department of Gastroenterology & Hepatology, Hinchingbrooke
Hospital, Hinchingbrooke, Huntingdon, UK
Abstract
Non-alcoholic fatty liver disease (NAFLD) is currently the
most common chronic liver disease in developed countries
because of the obesity epidemic. The disease increases liver-
related morbidity and mortality, and often increases the risk
for other comorbidities, such as type 2 diabetes and cardio-
vascular disease. Insulin resistance related to metabolic
syndrome is the main pathogenic trigger that, in association
with adverse genetic, humoral, hormonal and lifestyle factors,
precipitates development of NAFLD. Biochemical markers
and radiological imaging, along with liver biopsy in selected
cases, help in diagnosis and prognostication. Intense lifestyle
changes aiming at weight loss are the main therapeutic
intervention to manage cases. Insulin sensitizers, antioxi-
dants, lipid lowering agents, incretin-based drugs, weight loss
medications, bariatric surgery and liver transplantation may
be necessary for management in some cases along with
lifestyle measures. This review summarizes the latest evi-
dence on the epidemiology, natural history, pathogenesis,
diagnosis and management of NAFLD.
Citation of this article: Pappachan JM, Babu S, Krishnan B,
Ravindran NC. Non-alcoholic fatty liver disease: A clinical up-
date. J Clin Transl Hepatol 2017;5(4):1–10. doi: 10.14218/
JCTH.2017.00013.
Epidemiology
Non-alcoholic fatty liver disease (NAFLD) has emerged as the
most prevalent chronic liver disease in developed nations in
recent years. It is defined as the presence of $5% steatosis
in the absence of secondary causes of fat accumulation in the
liver (described below). Prevalence of NAFLD is growing, even
in the developing world, because of the global obesity
epidemic. Moreover, very close association between the
disease and metabolic syndrome has been identified.
Epidemiological data shows the global prevalence of
NAFLD in different populations as follows: United States –
30%, Middle East –32%, South America –30%, Asia –27%,
Europe –24% and Africa –13%.
1
Wide variations in the prev-
alence have also been identified among different ethnic
groups of these populations. Another interesting trend
noted is the increasing prevalence of NAFLD among paediatric
age groups. Autopsy-based data showed that NAFLD preva-
lence among children aged 2–19 years to be 9.6% after
adjustment for age, sex, race and ethnicity, and up to 38%
in obese children.
2
The disease starts with fatty liver or hepatic steatosis and
may progress to steatohepatitis with hepatic inflammation.
Five to twenty percent of patients with fatty liver develop
nonalcoholic steatohepatitis (NASH) in their clinical course, of
which 10–20% develop into higher-grade fibrosis and <5%
progress to full-blown cirrhosis.
3
The prevalence of NASH
may be underestimated, as the diagnosis requires histological
confirmation. It is considered that at least 5% of the popula-
tion may have NASH.
4
Prevalence of NAFLD among the at-risk
group is even higher.
Eighteen to thirty-three percent of cases with NAFLD
were found to have type 2 diabetes mellitus (T2DM), and up
to 66–83% of NAFLD cases were identified with markers of
insulin resistance (IR).
5–7
Even without a significant degree of
dyslipidaemia, increasing levels of low-density lipoprotein
cholesterol (LDL) levels (ranging from < 2.0 mmol/L to
2.7 mmol/L) increased the prevalence of NAFLD from 19%
to 42% in patients in a recent study.
8
Prevalence of NAFLD
also increases with age (up to 46%), with the older age
groups having higher mortality rates.
9,10
Natural history
The natural history of NAFLD is not well established, with
significant knowledge gaps about the marked inter-individual
variations in disease onset, progression, and complications.
NAFLD represents a wide spectrum of clinical entities from
asymptomatic hepatic steatosis to more advanced liver
disease with hepatic failure or hepatocellular carcinoma
(HCC).
1,11,12
The rate of disease progression in most cases
is slow, although rapid development of advanced liver disease
may be occasionally found. About one-third of people even-
tually develop NASH;
1,11,12
however, regression of fibrosis is
also noticed in about 20% of these cases.
12,13
Journal of Clinical and Translational Hepatology 2017 vol. XX | 1–10
Copyright: © 2017 Authors. This article has been published under the terms of Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0), which
permits noncommercial unrestricted use, distribution, and reproduction in any medium, provided that the following statement is provided. “This article has been published
in Journal of Clinical and Translational Hepatology at DOI: 10.14218/JCTH.2017.00013 and can also be viewed on the Journal’s website at http://www.jcthnet.com”.
Keywords: Nonalcoholic fatty liver disease (NAFLD); Nonalcoholic steatohepatitis;
NASH; Insulin resistance; Metabolic syndrome; Lifestyle interventions; Bariatric
surgery.
Abbreviations: ALT, alanine aminotransferase; AST, aspartate transaminase; CT,
computed tomography; DPP-4, dipeptidyl peptidase-4; FXR, farnesoid X receptor;
GLP-1, glucagon-like insulinotropic peptide-1; HDL, high density lipoprotein; HCC,
hepatocellular carcinoma; IR, insulin resistance; LDL, low density lipoprotein; MRI,
magnetic resonance imaging; MS, metabolic syndrome; NAFLD, nonalcoholic fatty
liver disease; NAS, NAFLD activity score; NASH, nonalcoholic steatohepatitis; NFS,
NAFLD fibrosis score; OCA, obeticholic acid; PCSK9, proprotein convertase subtili-
sin/kexin type 9; PPAR, peroxisome proliferator activated receptor; RCT, random-
ized control trial; SAF score, steatosis, inflammatory activity and fibrosis score;
T2DM, type 2 diabetes mellitus; TE, Transient elastography; VLDL, very low
density lipoprotein.
Received: 24 February 2017; Revised: 31 May 2017; Accepted: 24 June 2017
*Correspondence to: Dr. Joseph M Pappachan, Department of Endocrinology,
Diabetes & Metabolism, Royal Lancaster Infirmary, University Hospitals of More-
cambe Bay NHS Trust, Lancaster, LA1 4RP, UK. E-mail: drpappachan@yahoo.co.in
Although increased cardiovascular mortality rate has been
demonstrated in patients with NAFLD compared to general
population,
14
it is difficult to predict the risk for all-cause
mortality in the absence of large population-based epidemio-
logical study data. However, NASH was associated with a
three-fold increase in liver-related mortality compared to
the general population.
15
Although NAFLD-associated cirrho-
sis was previously considered to have a higher risk for the
development of HCC, recent evidence showed that up to
50% of patients with NAFLD-associated HCC did not have
cirrhosis.
15,16
Co-existent T2DM and obesity further increase
risk of developing HCC in patients with NAFLD.
17
Pathogenesis
NAFLD is considered as a metabolic disorder that results from
complex interaction between genetic, hormonal and nutri-
tional factors.
1
Recent evidence suggests that several genetic
risk factors predispose to the development and progression of
NAFLD.
18
For example, polymorphisms of PNPLA3, TM6SF2,
FTO,LIPA,IFNl4 HFE, and HMOX-1 genes have been found to
be associated with development/progression of the disease.
Obesity and metabolic syndrome (MS) are the most
important risk factors identified in the development of
NAFLD, and diabetes mellitus and hypertension are also
linked to greater progression of the disease.
19,20
Because of
the similarity in pathogenesis –IR leading to hyperinsulinemia
and gross alterations in carbohydrate and fat metabolism –
NAFLD and T2DM often co-exist in many individuals with met-
abolic syndrome. Moreover, both the disorders modify the risk
for each other in a vicious circle.
21
Full-blown T2DM also con-
tributes to further worsening of hepatic steatosis and pro-
gression of established NASH, fibrosis and cirrhosis, with a
higher risk of development of HCC.
20,21
Hyperinsulinemia and IR lead to increased adipocyte lip-
olysis and circulating free fatty acids (FFAs) that are taken
up by hepatocytes, initiating various complex metabolic
pathways that lead to NAFLD (Fig. 1).
22
Because of the very
strong association with MS, NAFLD is considered as the
hepatic component of MS.
20,22
Systemic IR reduces plasma
adiponectin (an adipokine that increases insulin sensitivity
and reduces inflammation) levels and increases the concen-
tration of leptin (a cytokine secreted by adipocytes that plays
a role in reducing body weight and fat mass). Reduced adipo-
nectin levels
23
and increased leptin levels (possibly from
leptin resistance)
24
are observed in patients with NAFLD.
22
Adipose tissue lipolysis continues, even with hyperinsuli-
nemia, because of the IR that results in increased plasma FFA
concentration. Liver takes up the FFA in circulation, that if not
oxidised gets stored in the liver in various forms or exported
as very low density lipoproteins (VLDLs), as shown in the
figure. High hepatic VLDL output also results in high circulat-
ing triglycerides and LDL and low circulating high density
lipoprotein (HDL) levels that increase atherosclerosis risk.
25
Increased glucagon levels with altered insulin/glucagon
ratio is seen in patients with NAFLD.
22
This promotes hepatic
de novo lipogenesis (DNL), glycogenolysis and gluconeogen-
esis with higher hepatic glucose production and IR. Several
gastrointestinal hormones and adipokines that regulate
glucose and lipid metabolism, along with hormones control-
ling appetite and satiety, are also thought to contribute to the
pathogenesis of NAFLD.
1,20–22
Glucagon-like insulinotropic
peptide-1 (GLP-1), ghrelin, selenoprotein P, leptin, adiponec-
tin and the myokine –irisin –are some of these chemicals.
22
As in the case of T2DM, the predominant risk factor for
development of NAFLD is IR because of overweight/obesity
that result from adverse lifestyle factors, such as over-
nutrition and physical inactivity. Although the majority of
cases with NAFLD are obese/overweight individuals, a small
but significant proportion of patients with the disease are
lean. This phenomenon is especially common in the non-
Caucasian populations, accounting for about 20% of cases.
26
Predominant visceral obesity rather than generalized
obesity, high dietary intake of fructose and cholesterol, and
genetic risk factors may predispose to non-obese NAFLD.
27
Higher rates of the mutant PNPLA3 gene variants and
reduced serum adiponectin concentrations were reported in
Caucasians with lean NAFLD compared to controls in a recent
report.
28
Potential roles of various lysophosphatidylcholines,
phosphatidylcholines, lysine, tyrosine and valine were
revealed in these cases using metabolomics studies.
Physical activity stimulates production of various soluble
chemicals from muscle fibres, collectively termed as myo-
kines, that show auto, para and endocrine functions.
29,30
These myokines function as messengers between skeletal
muscle and other tissues, such as liver, adipose tissue,
heart, brain and blood vessels, signalling cascades of neuro-
hormonal changes that modulate energy balance, metabo-
lism and homeostasis. Although several myokines are
described that may alter human metabolism, irisin is the
most studied one among them. Physical activity increases
irisin levels, leading to thermogenesis with a possible protec-
tive effect on metabolic disorders.
31
However, there are
studies showing increased levels of irisin in patients with met-
abolic syndrome and NAFLD.
32,33
Acute response to exercise is shown to involve an increase
in plasma irisin levels, whereas chronic exercise leads to
reduction of the levels.
34
Therefore, these conflicting reports
on the plasma levels and metabolic effects of irisin may be
related to development of resistance to the hormone or its
effectors at tissue level that should be elucidated in future
research. With the available evidence, we can conclude that
by modulation of multiple metabolic parameters and the
effects on body energy homeostasis, irisin may alter the risks
for obesity, T2DM, NAFLD and cardiovascular disease.
30,35
Alterations in the functions and composition of gut micro-
biome, otherwise known as intestinal dysbiosis, have been
found to associated with obesity and its consequent metabolic
disorders, including NAFLD, in animal models.
36
Several sub-
sequent studies in animal models and humans revealed clear
association between gut dysbiosis and NAFLD.
37–40
Even the
degree of intestinal dysbiosis has been found to be correlated
to the severity of NAFLD and the fibrosis.
41
Several local
and systemic factors, such as disruption of gastrointestinal
mechanical barrier function,
42
inflammation,
38,43
various
metabolites released by intestinal microbial metabolism/
actions,
44–46
and ethanol production by the microbiota
39,47
were proposed as the potential pathogenic mechanisms.
Fig. 2 summarizes the pathogenesis of NAFLD and the
potential therapeutic targets.
Diagnosis
NAFLD remains asymptomatic in a significant proportion of
patients, and the diagnosis is often suspected when liver
functions are found abnormal on biochemical testing or
hepatic imaging (ultrasonography, computed tomography
[CT] or magnetic resonance imaging [MRI] of liver) suggest
2 Journal of Clinical and Translational Hepatology 2017 vol. XX | 1–10
Pappachan J.M. et al: Non-alcoholic fatty liver disease
fatty liver, when performed for some other reasons. The
diagnosis of NAFLD is established when $5% of the hep-
atocytes show steatosis in the absence of causes for secon-
dary steatosis, such as excessive alcohol consumption (> 20
grams/day in females and 30 grams/day in males) or chronic
liver conditions associated with steatosis (viral, autoimmune,
metabolic and toxic disorders).
1,48,49
Biochemical markers
Liver enzymes can often be normal in a number of patients
with NAFLD. For example, alanine aminotransferase (ALT) can
be normal in up to 60% of patients with NASH, and 53% of
patients with high ALT had no evidence of NASH and advanced
fibrosis.
50,51
Although several biochemical markers, such as
TNF-a, IL-6, CRP, Pantraxin, Ferritin, serum prolidase enzyme
activity, soluble receptor for advanced glycation end product
and cytokeratin-18, have been proposed as useful in predict-
ing the severity of NAFLD/NASH in the past, none of these
markers have shown sufficient sensitivity or specificity for
routine clinical application for diagnosis.
52
NAFLD fibrosis score (NFS) using clinical and biochemical
parameters to predict the severity of liver involvement is the
most validated non-invasive tool to assess the disease. NFS is
based on age, body mass index, aspartate transaminase
(AST), ALT, platelets, albumin, and presence or absence of
impaired fasting glucose.
1
A low cut-off score < 1.455
excludes advanced fibrosis with a negative predictive value
of 93%, while a high cut-off value exceeding 0.676 suggests
advanced fibrosis with a positive predictive value of 90%.
1,53
Although the specificity of NFS is good, the sensitivity was
recently reported as being low.
54
Fig. 1. Pathophysiological mechanisms involved in the development and complications of nonalcoholic fatty liver disease (NAFLD). BAT, brown adipose
tissue; DNL, de novo lipogenesis; FC, free cholesterol; FFA, free fatty acid; GLP-1, glucagon-like insulinotropic peptide; GNG, gluconeogenesis; IR, insulin resistance; LDL,
low density lipoprotein; SeP, selenoprotein P; VLDL, very low density lipoprotein; WAT, white adipose tissue. Figure reproduced with permission from Petta et al.
22
Journal of Clinical and Translational Hepatology 2017 vol. XX | 1–10 3
Pappachan J.M. et al: Non-alcoholic fatty liver disease
Radiological diagnosis
Ultrasonography, CT and MRI of the liver are the standard
imaging modalities used in clinical practice for diagnosis of
NAFLD. In general, about 30% of liver steatosis should be
present for these techniques to detect NAFLD.
1,20,48
Ultraso-
nography is cheap, available easily and easy to perform, even
from the bedside. The reported sensitivity of the test is > 90%
in experienced hands when hepatic steatosis is >30%,
although the sensitivity is much lower at lower degrees of
steatosis.
55,56
However, ultrasonography is highly operator-
dependent and, therefore, results can vary widely depending
on the performer.
Transient elastography (TE) is an ultrasound-based
imaging technique to detect the degree of fibrosis in patients
with NAFLD and NASH. Sensitivity and specificity of TE to
diagnose various stages of fibrosis have been reported to be
79–92% and 75–92% respectively.
57
Recent evidence also
suggests that ultrasound-based controlled attenuation
parameter value used in the TE technique can predict the
degree of steatosis in patients with NAFLD.
58
CT scan is reported to be highly sensitive in quantifying the
hepatic and visceral fat to measure the degree of adiposity in
patients with metabolic syndrome and NAFLD.
59
However, the
test is expensive and associated with risk of radiation, and,
therefore, not usually recommended in clinical settings. MRI
is highly sensitive and specific for both quantitative and qual-
itative assessment of NAFLD. Newer MRI techniques, such as
MR elastography, proton density fat fraction and the FerriScan
method, can stage the degree of fibrosis non-invasively to
diagnose and assess the prognosis of patients with
NAFLD.
59
However, these techniques are expensive and avail-
able only in specialized centres.
Liver biopsy and histology
Liver biopsy remains the gold standard for diagnostic evalua-
tion of NAFLD. Biopsy not only confirms the diagnosis but
provides information on extent of fibrosis and steatosis,
necro-inflammation, and architectural distortion. In the
past, the NASH Clinical Research Network histological
scoring system was the widely used histological scoring
system, representing a validated scoring system that gen-
erates a NAFLD activity score (NAS). A NAS score of 5 or > 5 is
considered NASH and < 3 is not NASH.
60
However, recent evidence suggests that NAS score cannot
be used as a surrogate for discrimination between NASH and
NAFLD, although it is useful for the histological diagnosis.
61,62
Therefore, the European Association for the Study of liver
recommends NAS for evaluation of the disease activity, and
not for the diagnosis. The steatosis, inflammatory activity and
fibrosis (SAF) score introduced in 2012, provides a reliable
and reproducible measure for the diagnosis, grading and
staging of NAFLD without much inter-observer variability.
63
SAF score assesses both and separately the grade of steatosis
(S), the grade of activity (A), and the stage of fibrosis (F), the
latter according to the NASH Clinical Research Network.
Cost, procedure-related complications and intra- and
inter-observer variations in reporting the histology are the
major draw backs of liver biopsy, and, therefore, it is usually
not recommended in clinical practice, except in circumstances
where other differential diagnoses are to be excluded.
Treatment of NAFLD
There is no single intervention that is proven to be fully
effective in the treatment and cure of NAFLD. The main goals
of treatment are to improve steatosis and to prevent pro-
gression of the disease. Intense lifestyle modification and
treatment of the risk factors are the cornerstones of disease
management. Medical and surgical interventions serve as
second-line treatments, or as adjuvants.
Lifestyle interventions
Sustained and effective weight loss through calorie restriction
and increased physical activity have been shown to improve
liver function and histology in multiple studies.
64,65
Both
exercise and dietary interventions in isolation or in combina-
tion have been shown to improve biochemical and histological
parameters of NAFLD. Low-carbohydrate high-fat diet has
been shown to be effective in improving all the abnormal clin-
ical and biochemical parameters of metabolic syndrome and
NAFLD in multiple studies.
66
These dietary interventions are
also associated with weight loss in patients. Even without sig-
nificant weight loss, however, lifestyle interventions were
found to improve NAFLD, especially if patients are adherent
to the changes.
67
Yet, patient compliance issues always rep-
resent a challenge to these interventions.
Insulin sensitizing agents
Being a disease associated with IR and metabolic syndrome,
insulin sensitizing agents are expected to alter the pathophy-
siological mechanisms of NAFLD. Metformin and the thiazo-
lidinedione group of antidiabetic agents are the most studied
medications in this group.
Metformin
Although metformin use was associated with significant
improvements in IR and liver transaminases (AST and ALT),
the drug failed to show improvement in the histological
parameters, such as steatosis, inflammation, hepatocellular
ballooning and fibrosis.
68
However, because of the
Fig. 2. Pathogenesis of nonalcoholic fatty liver disease and effects of
various therapeutic interventions. indicates positive effect and indicates
negative effect.
4 Journal of Clinical and Translational Hepatology 2017 vol. XX | 1–10
Pappachan J.M. et al: Non-alcoholic fatty liver disease
antidiabetic efficacy, metformin should be considered for
patients with T2DM or even prediabetic states and NAFLD.
Metformin is found to be safe, even in patients with cirrhosis,
and may protect against development of HCC in cases with
T2DM and chronic liver diseases.
69
Thiazolidinediones
These drugs modulate tissue insulin sensitivity through the
peroxisome proliferator activated receptor (PPAR)-gsignal-
ling, and improve blood glucose control. Rosiglitazone and
pioglitazone are the agents widely studied in this class of
drugs for management of T2DM. Following the controversy
about increased cardiovascular events, rosiglitazone use has
been much lower in recent years, with pioglitazone being the
agent widely used currently. Pioglitazone has been shown to
improve the hepatic insulin sensitivity and fatty acid oxida-
tion, and to inhibit hepatic lipogenesis.
70
There is moderate
quality evidence to suggest the benefits of pioglitazone in
improvement of biochemical and histological parameters of
NAFLD, although the drug use may be associated with
weight gain.
71,72
In combination with intense lifestyle modi-
fication, this drug should be considered in patients with NASH.
Antioxidants
Oxidative stress plays a major role in the pathogenesis of
NAFLD and several investigators studied the effects of anti-
oxidants extensively.
71–74
Vitamin E is the most studied anti-
oxidant in this group. Supplementation of this was associated
with significant improvement in all histological parameters,
such as steatosis, hepatocyte ballooning, lobular inflamma-
tion and fibrosis, as compared to placebo.
73
Vitamin E is used
in the dose of 800 International Units daily for patients with
NASH, especially in non-diabetic cases.
1,74
Although multiple
agents such as N-acetylcysteine, betaine, probucol, viusid,
and silibinin (milk thistle) have been used in different trials,
the use of these agents are not recommended in current clin-
ical practice because of conflicting/insufficient evidence on
the benefits.
74
Incretin-based therapy
There are two main groups of incretin-related drugs exten-
sively studied for use in NAFLD, viz., GLP-1 analogues
(e.g., exenatide, liraglutide, lixisenatide, dulaglutide and sem-
aglutide) and dipeptidyl peptidase-4 (DPP-4) inhibitors (e.g.,
sitagliptin, saxagliptin, vildagliptin, alogliptin and linagliptin).
Both classes of drugs augment the meal-related insulin
secretion from the pancreas, along with extra-pancreatic
effects on multiple organs that make them very useful for the
management of T2DM.
75
Use of GLP-1 analogues are associ-
ated with weight loss, and DPP-4 inhibitors are weight neutral.
Incretin-based therapy is very commonly used in overweight/
obese T2DM patients, many of whom suffer from NAFLD as
well. Remarkable benefits of both the conditions make this
class of agents unique in managing the cases.
20
Recent evidence suggests that patients with NASH, partic-
ularly those with T2DM, get significant benefits from GLP-1
analogue therapy, with improvement in liver histology and
reduction in liver transaminase levels from baseline.
76–78
In
patients with NAFLD/NASH with or without T2DM, the benefits
of GLP-1 analogue therapy may outweigh the risk of use, and,
therefore, it should be considered. Although less effective,
DPP-4 inhibitors are also reported as effective in patients
with NAFLD and T2DM.
20,79
Lipid lowering agents
Lipid lowering agents are useful for treatment, especially
in patients with concurrent dyslipidaemia and NAFLD.
A Cochrane review in 2013 reported possible improvements
in serum aminotransferase levels and ultrasonological abnor-
malities in cases treated with statins, although the studies
included in the review were small with high risk of bias.
80
The
review concluded that statins can improve the adverse out-
comes related to NASH in patients with concurrent diseases,
such as hyperlipidaemia, diabetes mellitus, and metabolic
syndrome. A more recent small randomized control trial
(RCT) found that rosuvastatin monotherapy could ameliorate
biopsy-proven NASH with resolution of metabolic syndrome
within 12 months of treatment.
81
Unfortunately, the potential
for complications associated with liver biopsy makes it diffi-
cult to perform large RCTs in patients with NASH.
In experimental models of NAFLD, fenofibrate use was also
found to reduce liver steatosis associated with high-fat diet,
T2DM and metabolic syndrome.
82
Some small clinical studies
also showed beneficial effects. However, small sample sizes
and lack of histological data limit the validity of these
results.
82
Multiple RCTs and meta-analyses showed beneficial
effects of omega-3 fatty acids both in adults and children with
NAFLD.
83–85
Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a
molecule secreted by hepatocytes that inhibits uptake of LDL
by targeting the receptor for degradation, and which aug-
ments lipogenesis.
86
Circulating PCSK9 levels have been
found to be elevated in patients with NAFLD. PCSK9 inhibitors
have been recently shown to be highly effective in reducing
hypercholesterolemia in patients with remarkable improve-
ment of the associated cardiovascular risk.
87
Because the treatment is expensive, these drugs are often
reserved for patients with statin intolerance and familial
forms of lipid disorders inadequately managed by full doses
of other lipid lowering agents.
Drugs for weight loss
Medications that help weight loss may potentially alter the
pathogenic mechanisms of NAFLD and may be useful in
selected patients. Most of these medications are associated
with only modest weight loss benefit and several of them have
been withdrawn from the market owing to undesirable side
effects.
Orlistat
This medication inhibits pancreatic lipase, resulting in fat
malabsorption and weight loss as a consequence. Although
two previous RCTs showed some beneficial effects of orlistat
in patients with NASH, it is not clear if the benefit was related
to weight loss conferred by the drug or direct effect.
88–90
Therefore, the drug use should be selected for individual
patients as per the clinician’s discretion and situation.
Lorcaserin
This is an appetite suppressant associated with about 4%
weight loss in 12 months when combined with lifestyle
Journal of Clinical and Translational Hepatology 2017 vol. XX | 1–10 5
Pappachan J.M. et al: Non-alcoholic fatty liver disease
changes.
91
Pooled data from three lorcaserin RCTs showed
that there was modest reduction in ALT levels and improve-
ment of cardiovascular outcomes in treated patients with
NAFLD compared to placebo.
92
Naltrexone/bupropion combination
This drug combination is associated with a weight loss of
approximately 5%. Modest reductions in hepatic aminotrans-
ferase levels were observed in patients who lost > 10%
weight in 12 months with higher dose of the combination.
93
Phentermine/topiramate
This combination is also associated with significant weight
loss benefit and may be associated with improvement of
NAFLD.
94
Liraglutide
High-dose liraglutide treatment (3 mg daily) has been
approved by the United States’Food and Drug Administration
and the European Medicine Agency recently for primary
management of obesity in patients without diabetes. About
8.5% weight loss has been observed in the treated patients
compared to placebo in a major clinical trial, although the
data on NAFLD was not available in this study.
95
However,
another recent phase 2 clinical trial reported significant
improvement of liver histology when 1.8 mg liraglutide was
administered to patients.
96
Therefore, high-dose liraglutide
treatment also may be associated with the same benefit.
Other novel agents
Pentoxyphylline is a competitive nonselective phosphodiester-
ase inhibitor which raises cyclic adenosine monophosphate
and inhibits tumour necrosis factor-a. Both animal studies and
clinical trials in humans showed beneficial effects of this novel
agent.
71,72,97
Although prebiotics and probiotics have been
claimed to be useful in the treatment and prevention of
patients with obesity and NAFLD, inadequate supporting data
from high-quality clinical studies is against recommendation
of the use of these medications in normal clinical practice.
98
Obeticholic acid (OCA) is a synthetic bile acid and agonist
of farnesoid X receptor (FXR) that has been recently devel-
oped for treatment of primary biliary cirrhosis and has shown
promise in the management of NAFLD.
99
FXR is an important
nuclear receptor involved in the regulation of bile acid,
glucose and cholesterol homeostasis in the human body.
94
Both animal and human studies showed beneficial effects of
OCA in the management of NAFLD.
99
Another novel agent
elafibranor, a PPAR-a/dagonist, was shown to improve
NASH without fibrosis worsening in patients with moderate
or severe NASH compared to placebo in a recent clinical
trial.
100
The drug is well tolerated and yields improved cardi-
ometabolic risk profile in patients.
Bariatric surgery
Obese patients undergoing bariatric surgery showed signifi-
cant improvements in both histological and biochemical
parameters of NAFLD in a recent meta-analysis.
101
Histolog-
ical features of the disease, such as steatosis, fibrosis,
hepatocyte ballooning and lobular inflammation, as well as
reduction in the liver enzyme levels including ALT, AST, alka-
line phosphatase and g-glutamyl transferase were observed
in patients who underwent surgery. In 2015, based on level B
evidence, the Japanese Society of Gastroenterology in coop-
eration with the Japan Society of Hepatology recommended
weight loss surgery as an effective treatment option for
patients with NAFLD/NASH complicated by severe obesity
for improving fatty changes in the liver and inflammation
associated with NASH.
102
Although there is no clear global consensus from different
professional bodies on the indications for recommending
metabolic surgery in patients with NAFLD, rapidly emerging
evidence may lead us towards such a consensus in near
future. The most recently published data from the STAMPDE
clinical trial that revealed remarkable improvements in the
parameters of metabolic syndrome following bariatric surgery
is a good example of such high-quality evidence.
103
Liver transplantation
Recent data suggests that NASH-related end-stage liver
disease is the third leading cause for hepatic transplants in
the United States and is expected to become the most
common cause for liver transplant in 1–2 decades because
of the obesity epidemic.
104
The upward global trend in the
prevalence of obesity is expected to cause the same health
burden in most other regions of the world in the near future.
Therefore, liver transplants would become a standard treat-
ment option in a significant proportion of patients with
advanced stages of NAFLD.
Based on level B and strength 2 evidence, the Japanese
Society of Gastroenterology in association with the Japan
Society of Hepatology recommend liver transplant for patients
with advanced NASH hepatic failure.
102
The overall survival
rates after hepatic transplantation in these patients are
almost identical to those receiving transplants for liver failure
from other hepatic disorders. However, almost one-third of
patients who receive liver transplant for NASH will have recur-
rence of the disease in the transplanted liver in the absence of
intense post-transplant lifestyle modifications.
105,106
Table 1. NASH Clinical Research Network histological scoring system
NAFLD activity score NASH fibrosis stage
Steatosis
<5%:0
5–33%: 1
34–66%: 2
> 66%: 3
Lobular
inflammation
None: 0
<2:1
2–4: 3
>4:4
Ballooning of
hepatocytes
None: 0
Few ballooned: 1
Many ballooned: 2
NAS score (0–8)
< 3: not NASH
$5: NASH
Stage 0
No fibrosis
Stage 1
Zone 3 perisinusoidal fibrosis
Mild –1a
Moderate –1b
Portal/periportal –1c
Stage 2
Perisinusoidal and portal/
periportal fibrosis
Stage 3
Bridging fibrosis
Stage 4
Cirrhosis
6 Journal of Clinical and Translational Hepatology 2017 vol. XX | 1–10
Pappachan J.M. et al: Non-alcoholic fatty liver disease
Table 2 summarizes some of the therapeutic agents avail-
able for management of patients with NAFLD/NASH and the
level of evidence for the use of these medications.
Conclusions
There has been an exponential increase in the global inci-
dence and prevalence of NAFLD because of the obesity
pandemic. In the absence of therapeutic interventions, sig-
nificant proportion of cases progress to NASH, with increased
morbidity and mortality. Diagnosis of NAFLD often depends on
biochemical and radiological investigations, as early stages of
the disease are often clinically silent. Management of the
disease primarily depends on intense lifestyle changes to lose
weight. Insulin sensitizers, antioxidants, incretin-based
drugs, lipid lowering agents, weight loss medications, bari-
atric surgery and liver transplantation are therapeutic options
that can be added to lifestyle interventions when necessary
for management of cases. Continued research for optimizing
management strategies of this common disorder is important
for reducing the global burden of NAFLD.
Conflict of interest
The authors have no conflicts of interests related to this
publication.
Author contributions
Prepared the initial draft (SB, BK), conceived the manuscript
plan, and grossly modified the initial draft which had been
prepared by (JMP), helped in draft modification and revision
of the paper (NCR). All authors contributed to the literature
search and writing of the final manuscript.
Table 2. Drug classes, main mode of actions and side effects, and level of evidence for use in clinical practice
Category of drug
Representative
drug Main mode of action
Main/serious
side effects
Evidence for benefit
in NAFLD/NASH
Biguanide Metformin Improved insulin sensitivity Gastrointestinal
upset
Recommended in
patients with T2DM and
NAFLD (1/444○)
Thiazolidinediones Pioglitazone Modulate tissue insulin
sensitivity through PPAR
Worsening heart
failure
Recommended in
patients with NASH and
T2DM (1/444○)
GLP 1 analogues Exenatide/liraglutide Suppress appetite, helps
weight loss and enhances
endogenous insulin production
Gastrointestinal
upset
Recommended in
obese/overweight T2DM
and NAFLD (1/444○)
DPP 4 inhibitors Sitagliptin/linagliptin Enhances endogenous insulin
production
Gastrointestinal
upset
Suggested in obese/
overweight T2DM with
NAFLD (2/44○○)
Antioxidants Vitamin E Reduces oxidative stress Haemorrhagic
stroke
Recommended in
patients with NASH and
without diabetes
(1/444○)
Phosphodiesterase
inhibitor
Pentoxyphylline Raises c-AMP and reduces
TNF-a
Upper
gastrointestinal
upset
Suggested in NASH
(2/44○○)
Statin Atorvastatin Lowers plasma lipids Muscle pains
and myopathy
Suggested in patients
with dyslipidaemia &
NAFLD (2/44○○)
Lipase inhibitor Orlistat Decreases fat absorption from
intestine and reduces body
weight
Diarrhoea Suggested in obese
patients (2/4○○○)
Farnesoid XR
agonist
Obeticholic acid Alters hepatic lipogenesis and
reduces steatosis and
inflammation
Pruritus Suggested in patients
with NASH (2/44○○)
PPAR-a/dagonist Elafibranor Reduces steatosis,
inflammation and fibrosis
Transient
increase in
serum
creatinine
Suggested in patients
with NASH (2/44○○)
The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system is used to describe the strength of recommendations and the quality of
evidence. Strong recommendations are denoted by “Recommend”and the number 1, and weak recommendations by the phrase “Suggested”and the number 2. Cross-filled
circles indicate the quality of the evidence, such that 4○○○ denotes very low quality evidence, 44○○ denotes low quality, 444○denotes moderate quality, and 4444
denotes high quality.
Journal of Clinical and Translational Hepatology 2017 vol. XX | 1–10 7
Pappachan J.M. et al: Non-alcoholic fatty liver disease
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