Drug-Induced Liver Injury Network (DILIN) prospective study: rationale, design and conduct.

Abstract

Drug-induced liver injury (DILI) is an uncommon adverse drug reaction of increasing importance to the medical community, pharmaceutical industry, regulatory agencies and the general public.
The Drug-Induced Liver Injury Network (DILIN) was established to advance understanding and research into DILI by initiating a prospective registry of patients with bona fide DILI for future studies of host clinical, genetic, environmental and immunological risk factors. The DILIN was also charged with developing standardized nomenclature, terminology and causality assessment instruments.
Five clinical sites, a data coordinating centre and senior scientists from the National Institute of Diabetes and Digestive and Kidney Diseases initiated the DILIN prospective study in September 2004. Eligible patients are required to meet minimal laboratory or histological criteria within 6 months of DILI onset and have other competing causes of liver injury excluded. Patients in the general community setting with pre-existing HIV, hepatitis B virus or hepatitis C virus infections and/or abnormal baseline liver biochemistries are eligible for enrollment. In addition, subjects with liver injury due to herbal products are eligible to participate. Control patients without DILI are also to be recruited in the future.
All referred subjects undergo an extensive review of available laboratory, pathology and imaging studies. Subjects who meet pre-defined eligibility criteria at the 6-month study visit are followed for 2 years to better define the natural history of chronic DILI. Causality assessment is determined by a panel of three hepatologists who independently assign a causality score ranging from 1 (definite) to 5 (unlikely) as well as a severity score ranging from 1 (mild) to 5 (fatal). During the first 3 years, 367 subjects were enrolled into the DILIN prospective study.
DILIN is a multicentre research network charged with improving our understanding of the aetiologies, risk factors and outcomes of DILI in the US. The network is meeting the targeted enrollment of ten patients per month and is developing a repository of clinical data and biological samples for future studies of DILI pathogenesis and outcome.

Full text

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Drug-Induced Liver Injury Network
(DILIN) Prospective Study
Rationale, Design and Conduct
Robert J. Fontana,1Paul B. Watkins,2Herbert L. Bonkovsky,3,4,5,6Naga Chalasani,7
Timothy Davern,8Jose Serrano9and James Rochon,10for the DILIN Study Group
1
2
3
Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, USA
Department of Internal Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
Department of Internal Medicine, Center for Liver and Digestive Diseases, Charlotte,
North Carolina, USA
Department of Medicine and Cannon Research Center, Carolinas Medical Center, Charlotte,
North Carolina, USA
Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, USA
Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
Department of Internal Medicine, Indiana University, Indianapolis, Indiana, USA
Department of Internal Medicine, University of California, San Francisco, California, USA
Liver Disease Research Branch, National Institutes of Diabetes and Digestive and Kidney Diseases,
National Institutes of Health, Bethesda, Maryland, USA
Duke Clinical Research Institute, Durham, North Carolina, USA
4
5
6
7
8
9
10
Abstract
Background: Drug-induced liver injury (DILI) is an uncommon adverse drug
reaction of increasing importance to the medical community, pharmaceutical
industry, regulatory agencies and the general public.
Objectives: The Drug-Induced Liver Injury Network (DILIN) was estab-
lished to advance understanding and research into DILI by initiating a pros-
pective registry of patients with bona fide DILI for future studies of host
clinical, genetic, environmental and immunological risk factors. The DILIN
was also charged with developing standardized nomenclature, terminology
and causality assessment instruments.
Methods: Five clinical sites, a data coordinating centre and senior scientists
from the National Institute of Diabetes and Digestive and Kidney Diseases
initiated the DILIN prospective study in September 2004. Eligible patients
are required to meet minimal laboratory or histological criteria within
6 months of DILI onset and have other competing causes of liver injury
excluded. Patients in the general community setting with pre-existing HIV,
hepatitis B virus or hepatitis C virus infections and/or abnormal baseline liver
biochemistries are eligible for enrolment. In addition, subjects with liver in-
jury due to herbal products are eligible to participate. Control patients
without DILI are also to be recruited in the future.
ORIGINAL RESEARCH ARTICLE
Drug Safety 2009; 32 (1): 55-68
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Results: All referred subjects undergo an extensive review of available
laboratory, pathology and imaging studies. Subjects who meet pre-defined
eligibility criteria at the 6-month study visit are followed for 2 years to better
define the natural history of chronic DILI. Causality assessment is de-
termined by a panel of three hepatologists who independently assign a causa-
lity score ranging from 1 (definite) to 5 (unlikely) as well as a severity score
ranging from 1 (mild) to 5 (fatal). During the first 3 years, 367 subjects were
enrolled into the DILIN prospective study.
Conclusion:DILIN is a multicentre researchnetwork charged withimproving
ourunderstandingoftheaetiologies,riskfactorsandoutcomesofDILIinthe
US. The network is meeting the targeted enrolment of ten patients per month
and is developing a repository of clinical data and biological samples for
future studies of DILI pathogenesis and outcome.
Background
Drug-induced liver injury (DILI) is the leading
cause of acute liver failure in the US and the most
common reason for US FDA regulatory actions
regarding approved medications.[1,2]Implicated
drugs include not only prescription medications
but also herbal products and over-the-counter
dietary supplements and medications.[3,4]Persons
who develop hepatocellular DILI with jaundice
have at least a 10% chance of dying from the
injury and DILI patients that progress to acute
liver failure have only a 25% chance of sponta-
neous recovery.[1,5]While DILI caused by a
particular agent can be serious, it is relatively
uncommon, with an estimated frequency that
ranges from 1 per 10000 to 1 per 10000000
patient-years of exposure. Therefore, the low
incidence of DILI coupled with the limited
knowledge of the biochemical mechanism(s) or
pathways responsible for this ‘idiosyncratic’ ad-
verse event make it difficult to identify high-risk
patients.[6]Some investigators have postulated
the importance of reactive metabolites or aber-
rant host metabolism and immune responses in
the pathogenesis of DILI but the precise mole-
cular mechanism(s) involved are largely un-
known.[6,7]Furthermore, pre-clinical testing does
not provide a reliable assessment of the hepato-
toxic risk of new medications, and because DILI
is a rare event, pre-marketing clinical studies
conducted in highly selected populations over a
relatively short period of time also may not detect
a potential for liver injury. Therefore, the hepato-
toxicity of a specific medication often becomes
apparent only after regulatory approval and
when the drug is used by large numbers of un-
selected patients in the general population.[2,6]
Even then,voluntary post-marketing surveillance
systems such as the FDA MedWatch programme
frequently lag behind in detecting ‘hepatotoxic
signals’ from newly approved drugs.[8]Finally,
the biochemical, clinical and histological features
of DILI from initial onset to clinical presentation
can not only mimic most other known forms of
acute and chronic liver disease but can also vary
substantially with a single agent.[9,10]Thus, at
present, there is no objective ‘gold standard’ for
diagnosing DILI and its identification largely
relies on excluding other more common causes of
liver disease and having a ‘compatible’ time of
onset and evolution.[2,10]
The National Institute of Diabetes and
Digestive and Kidney Diseases (NIDDK) estab-
lished the Drug-Induced Liver Injury Network
(DILIN) in 2003 to advance understanding
and research into DILI by selecting five clinical
sites and a data coordinating centre (DCC)
that had submitted competitive grant applica-
tions.[11,12]In this article we present the ratio-
nale, design and methods of the prospective
DILIN study.
56
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Aims and Objective
The primary aim of the prospective DILIN
study is to identify a large number of patients
with bona fide DILI that will allow for collection
of epidemiological data and biological samples
for future mechanistic studies. The DILIN study
aims to do this by creating within 6 months of
onset a registry and tissue bank from people who
have experienced liver injury due to prescription
and over-the-counter drugs as well as herbal
products. A prospective registry will allow in-
vestigation into clinical, immunological, environ-
mental and genetic risk factors by comparing
DILI cases with matched control patients with a
similar drug exposure history but without evi-
dence of liver injury. Since the natural history of
DILI is not well understood, all of the DILI cases
are to be re-evaluated 6 months after enrolment.
All participants agree to be re-contacted for up to
20 years for potential participation in additional
studies, such as those that explore the relation-
ship between genotype and phenotype or pedi-
gree studies. Lastly, the DILIN is charged with
developing and testing causality assessment in-
struments for drug, herbal and over-the-counter
medication-induced liver injury.
Methods
Prospective Study Design
Eligible patients with suspected DILI are
referred to one of the five DILIN sites or their
satellite affiliates. Patients may be referred by a
physician/medical provider at one of the clinical
sites, a physician/medical provider at a nearby
location or hospital or may refer themselves. The
DILI event must be attributable to one or more
prescription or over-the-counter medications or
herbal products. Subjects are categorized as
having ‘standard DILI’ if they did not have
known liver disease prior to starting the suspect
medication. In contrast, subjects with known
liver disease prior to DILI onset, such as chronic
hepatitis B virus (HBV) or chronic hepatitis C
virus (HCV) infection or fatty liver disease, are
referred to as ‘liver DILI’ patients.
Baseline Study Visit
After an informed consent document is signed,
all relevant laboratory, pathology and imaging
studies are reviewed to ensure that referred
patients meet entry criteria. A complete history
and physical examination are undertaken and
detailed information regarding medications, past
medical history, drug intolerances and symptoms
at DILI onset is obtained (table I). In parti-
cular, the patient is questioned about the lifetime
use of the suspect medication and agents in the
same therapeutic class identified from an elec-
tronic database (Lexi-Comp?, Lexi-Comp Inc.,
Hudson, OH, USA). In addition, recent alcohol
consumption, medication compliance and smo-
king history are obtained using interviewer-
administered questionnaires. Adult participants
also complete the Short Form-36 quality-of-life
form (Rand Corporation, Arlington, VA, USA)
and children complete the Pediatric quality-
of-life form (MAPI Research Institute, Lyon,
France).[13,14]These instruments were selected
because of their established validity, brevity and
frequent use in other studies of patients with
liver disease.
The type of liver injury at DILI onset is classi-
fied as hepatocellular, cholestatic or mixed
by the R ratio, which compares ALT and alka-
line phosphatase levels in multiples of their
upper limit of normal (ULN) based upon the first
available values after DILI onset. The R ratio is
calculated by the formula R=(ALT/ULN)/
(alkaline phosphatase/ULN). For eligible pa-
tients with acute hepatocellular injury (i.e. R>5),
diagnostic tests required at enrolment include:
total and, if positive, IgM antibody to hepatitis A
virus, hepatitis B surface antigen (HBsAg), anti-
body to hepatitis B core antigen, anti-HCV and
if positive HCV RNA, anti-nuclear antibody,
anti-smooth muscle antibody, IgM antibody to
cytomegalovirus, Epstein Barr-virus (EBV) sero-
logies or a monospot test and ceruloplasmin if
the patient is aged <50 years. A cross-sectional
abdominal imaging study such as an ultrasound,
abdominal CT or MRI is also required. Subjects
with a mixed (i.e. 5>R>2) or cholestatic (R<2)
biochemicalprofile atDILI onset are alsorequired
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to have all of the above completed as well as
an anti-mitochondrial antibody test. Serum a1-
antitrypsin and iron indices are recorded, if
available, but are not mandatory. Available liver
biochemistry results starting 8 weeks prior to in-
itiation of the suspect drug through the baseline
study visit are recorded as well as the results of
other selected laboratory tests (e.g. haemoglobin,
white blood cell count and serum creatinine).
Urine and whole blood samples are collected
at the baseline study visit. Plasma, serum and
lymphocytes for DNA extraction, EBV immor-
talization and proliferation assays are obtained
and stored at the NIDDK biosample repository
(Rutgers University, Piscataway, NJ, USA).
Routine laboratory tests obtained at each study
visit include a urinalysis, complete blood count,
liver biochemistries, international normalized
ratio (INR), serum amylase, lipase, creatinine
phosphokinase, g-glutamyl transpeptidase and
lactate dehydrogenase levels. For HIV-infected
patients and those with known chronic HBV or
HCV, detailed data regarding prior disease
status including available CD4 counts and viral
test results as well as antiviral treatment are col-
lected. The site investigator also generates a
written clinical narrative summarizing the DILI
event for causality assessment. For patients
with DILI due to herbal products, the brand
name, manufacturer and ingredients of each
product are recorded. In addition, samples of the
suspect herbal product are collected and for-
warded to the US National Institutes of Health
(NIH) for future analysis of ingredient content.
Table I. Visit schedule in the Drug-Induced Liver Injury Network (DILIN) prospective study
Item Data sourceBaseline visit6-mo study visit12- and 24-mo
study visit
Chronic DILIc
Eligible patients Standard DILIa,
liver DILIb, control
Standard DILI,
liver DILI
DemographicsInterview
?
Pharmacy use Interview
?
Medication compliance Interview
?
Family history
Diagnostic laboratory testsd
Interview
Records/visit
Interview/records
Records/visit
Interview/records
?
?
Suspect medication use
HCV/HBV laboratory testse
?
??
Concomitant medication and
CAM use history
???
Alcohol and smokingInterview
???
Physical examinationVisit
???
Symptom scoreInterview
???
Quality-of-life surveyInterview
Interview/records
Records/visit
???
Medical history
???
Standard laboratory tests
???
Research blood sampleVisit
???
Research urine sample
Liver imaginga
Standard DILI case=normal liver biochemistries or no known liver disease before starting the suspect medication.
Liver DILI case=known chronic liver disease such as chronic HCV or HBV or fatty liver before starting the suspect medication.
Chronic DILI case=evidence of persistent laboratory, radiological or pathological abnormalities 6mo after DILI onset.
Visit
???
Records
???
a
b
c
dNot done in control patients.
e
CAM=complementary and alternative medicine; DILI=drug-induced liver injury; HBV=hepatitis B virus; HCV=hepatitis C virus.
Only in HCV/HBV liver DILI patients.
58
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Inclusion and Exclusion Criteria
Participants are required to have experi-
enced a DILI event within 6 months of the
baseline visit (table II). The DILI onset date is
defined as the first date after starting the sus-
pect medication wherein the subject met the
laboratory entry criteria. Both children and
adults are eligible to participate, the minimum
subject age being 2 years. Inclusion labora-
tory criteria are a serum AST or ALT >5 times
ULN (or pretreatment baseline if baseline levels
are elevated) on two separate occasions. Alter-
natively, subjects with serum alkaline phospha-
tase levels >2 times ULN (or baseline if the
baseline level is abnormal) on two consecu-
tive occasions may qualify. In addition, subjects
who develop a serum total bilirubin of greater
than 2.5mg/dL or an INR above 1.5 in the
absence of a competing cause of hyperbili-
rubinaemia or hypoprothrombinaemia, respec-
tively, are eligible.
Exclusion criteria are known or suspected
paracetamol (acetaminophen) overdose as well
as a history of bone marrow or liver transplant
prior to DILI onset. Subjects with pre-existing
immune-mediated liver disease such as auto-
immune hepatitis are also excluded. However,
subjects with unexplained abnormal liver bio-
chemistries or with pre-existing chronic HBV,
chronic HCV and HIV infection are allowed to
participate in light of the high prevalence of these
conditions in the general population.[15-17]
Six-Month Study Visit
At the 6-month study visit, interval medical
history, laboratory tests, medication use and liver
imagingarereviewed(tableI).Insubjectswithpre-
existing chronic HBV, a quantitative HBV DNA,
hepatitis B e antigen and antibody measurements
are obtained. Similarly, in subjects with pre-
existing chronic HCV, a quantitative HCV RNA
Table II. Entry criteria for the Drug-Induced Liver Injury Network (DILIN) prospective study
Inclusion criteria
Age >2ya
Enrolled within 6 mo of liver injury onset due to a drug or herbal product
Any one of the following laboratory criteria must be present
(i) If serum liver biochemistries were normal prior to starting suspect drug
serum ALT >5·ULN on two consecutive occasions or
serum AST >5·ULN on two consecutive occasions or
serum alkaline phosphatase >2·ULN on two consecutive occasions
(ii) If serum liver biochemistries were elevated prior to starting suspect drug
serum ALT >5·pre-drug average on two consecutive occasions or
serum AST >5·pre-drug average on two consecutive occasions or
serum alkaline phosphatase >2·pre-drug average on two consecutive occasions
(iii) Serum total bilirubin >2.5mg/dL and an elevated AST, ALT or alkaline phosphatase (without known haemolysis or
Gilbert’s syndrome)
(iv) INR >1.5 along with an elevated AST, ALT or alkaline phosphatase (without known coumadin therapy or vitamin K deficiency)
Exclusion criteria
Paracetamol (acetaminophen) hepatotoxicity
Pre-existing liver disease such as primary biliary cirrhosis, primary sclerosing cholangitis, autoimmune hepatitis or other chronic biliary tract
disease that may confound diagnosis
Liver or bone marrow transplant prior to enrolment
Identifiable competing cause of liver injury felt to be responsible for observed liver injury
a
DILI=drug-induced liver injury; HBV=hepatitis B virus; HCV=hepatitis C virus; INR=international normalized ratio; ULN=upper limit of
normal.
Age restriction due to need for blood withdrawal.
The DILIN Prospective Study 59
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