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ORIGINAL RESEARCH
A Cross-Sectional Study Comparing the Frequencyof Drug Interactions After Adding Simeprevir-
or Sofosbuvir-Containing Therapy to MedicationProfiles of Hepatitis C Monoinfected Patients
Nimish Patel • Mona Nasiri • Arden Koroglu • Steven Bliss •
Melissa Davis • Louise-Anne McNutt • Christopher Miller
To view enhanced content go to www.infectiousdiseases-open.comReceived: November 10, 2014 / Published online: January 28, 2015 The Author(s) 2015. This article is published with open access at Springerlink.com
ABSTRACT
Introduction: This study compares the
expected occurrence of contraindicated drug–
drug interactions (XDDIs) when simeprevir
(SIM)- or sofosbuvir (SOF)-containing therapy
is added to medication profiles of patients with
hepatitis C (HCV) monoinfection to quantify,
in relative terms, the population-based risk of
XDDIs. Second, this study identified the
predictors of XDDIs when HCV therapies areadded to medication profiles.
Methods: A cross-sectional study was
performed among Veterans’ Affairs patients.
Inclusion criteria were: (1) ageC18 years, (2)HCV infection, and (3) availability of a
medication list. Patients with human
immunodeficiency virus were excluded.
Demographics, comorbidities, year of HCV
diagnosis, and most recent medication list
were collected from medical records. The
primary outcome was the presence of XDDIs
involving HCV therapy and the medications in
the patient’s home medication list after the
addition of either SIM- or SOF-containingregimens. To define XDDIs, Lexi-Interact drug
interaction software was used.
Results: 4,251 patients were included. The
prevalence of XDDIs involving SIM- or SOF-
containing therapy were 12.6% and 4.7%
( p\0.001), respectively. In multivariable
analyses examining the predictors of XDDIs
involving SIM-containing therapy, the only
medication-related predictor was use of C6
home medications (odds ratio OR 4.58, 95%confidence interval CI 3.54–5.20, p\0.001).
Similarly, use of C6 home medications was
also the only variable associated with an
increased probability of XDDI involving SOF-
containing therapy (OR 3.83, 95% CI 2.57–5.70,
p\0.001).
Electronic supplementary material The onlineversion of this article (doi:10.1007/s40121-015-0058-x)contains supplementary material, which is available toauthorized users.
N. Patel (&) M. Nasiri A. Koroglu S. Bliss M. DavisAlbany College of Pharmacy and Health Sciences,
106 New Scotland Avenue, Albany, NY 12208, USAe-mail: [email protected]
L.-A. McNuttInstitute for Health and the Environment,University at Albany, State University of New York,Albany, NY, USA
C. MillerDepartments of Pharmacy and Medicine, UpstateUniversity Hospital, Syracuse, NY, USA
Infect Dis Ther (2015) 4:67–78
DOI 10.1007/s40121-015-0058-x
http://dx.doi.org/10.1007/s40121-015-0058-xhttp://dx.doi.org/10.1007/s40121-015-0058-x
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without hepatic coma), and 070.71 (unspecified
hepatitis C with hepatic coma). Each of these
patients was screened to confirm HCV infection
and for the following inclusion criteria: (1)
age C18 years, (2) laboratory-confirmed HCV
infection, and (3) availability of a medication
list. Patients with (HIV) were excluded because
of the strong influence of antiretroviral therapy
on the probability of XDDIs [11].
Data were obtained from the patients’
medical records related to demographics,
concomitant medical problems, year HCV
infection was diagnosed, and medication list.
Demographic characteristics included age, sex,
race (African American, Hispanic, Caucasian,
and other), height and weight. Concomitant
medical problems were obtained from the
clinical progress note. The most recent
medication list in the patients’ medical
records was obtained and used in this
analysis. For each medication, the drug name,
dose, and frequency were recorded.
Polypharmacy was defined as the use of
multiple medications.
The outcome of interest was the presence of
XDDIs involving HCV therapy and the
medications in the patient’s most recent
medication list (home medications) after the
addition of either SIM- or SOF-containing
regimens. SIM, pegylated interferon, and
ribavirin were used to define SIM-containing
therapy. Analogously, SOF-containing therapy
was defined as SOF, pegylated interferon and
ribavirin.
To define XDDIs, Lexi-Interact druginteraction software (Lexicomp, Hudson, USA)
was used [12]. The drug–drug interactions
that Lexi-Interact ranked as X-rated
(contraindicated) were considered XDDIs. All
of the patients’ home medications were entered
into Lexi-Interact, and the number of XDDIs
was recorded. Then, SIM-containing therapy
was added to the existing home medications
and the number of identified additional XDDIs
was recorded. Finally, SIM-containing therapy
was removed from Lexi-Interact and replaced
with SOF-containing therapy, and the number
of additional XDDIs was recorded.
To assess the data for the first study
objective, McNemar’s test was used to compare
the frequencies of XDDIs after adding SIM- and
SOF-containing therapy to patients’ home
medication profiles. For study objective #2
(predictors of XDDI involving SIM- and SOF-
containing therapy), bivariate analyses were
performed to assess the relationship between
the clinical covariates and XDDIs after the
addition of a SIM- and SOF-containing HCV
regimen to the patients’ medication lists. The v2
or Fisher’s exact tests were used to evaluate
categorical variables. The Student’s T or Mann–
Whitney U tests were used to compare
continuous data. Variables present in more
than 5% of the population and associated with
an XDDI involving SIM- and SOF-containing
therapy in the bivariate analyses ( p\0.25) were
entered into the multivariate regression
analyses. A backward stepwise approach was
used to identify the most parsimonious models.
Effect modification was evaluated by including
interaction terms in the multivariate models.
Classification and regression tree (CART)
analysis was used to identify thresholds in
continuous variables at which the likelihood
of an XDDI distinctly differs. All calculations
were computed using SPSS version 11.5 (SPSSInc, Chicago, IL, USA), SAS version 9.3 (SAS
Institute, Cary, NC, USA), and CART software
(Salford Systems, San Diego, CA, USA).
This article does not contain any new studies
with human or animal subjects performed by
any of the authors.
Infect Dis Ther (2015) 4:67–78 69
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RESULTS
There were 4,251 patients who met inclusion
criteria. The mean ± standard deviation (SD)
age was 59.8 ± 7.6 years. The majority
(n = 4,102, 96.5%) of patients were male.
Caucasian race (n = 2,476, 58.2%) was
observed most frequently, followed by African
American (n = 1,219, 28.7%), other (n= 438,
10.3%), and Hispanic (n = 118, 2.8%). The
median (interquartile range, IQR) number of
years since HCV diagnosis was 12 (8–14). The
median (IQR) numbers of comorbidities and
home medications used were 7 (5–10) and 7
(4–11), respectively. There were 477 (11.2%)
patients with cirrhosis.
The prevalence of XDDI before the addition
of SIM- or SOF-containing therapy was 16.7%
(n = 709). After the addition of SIM- and SOF-
containing therapy, the overall prevalence of
XDDIs significantly increased to 25.9%
(n = 1,103) and 19.9% (n = 844, p\0.001),
respectively. When restricting interactions to
only those involving SIM- or SOF-containing
therapy (Fig. 1), the prevalence of XDDIs after
the addition of these drugs was 12.6% (n = 535)
and 4.7% (n = 201, p\0.001) for SIM- and SOF-
containing therapies, respectively. Upon
stratification by the CART-derived breakpoints
(\ or C6 home medications and having \ or
C10 comorbidities), there were significant
differences in the frequency of XDDIs
involving HCV therapy between SIM- and
SOF-containing regimens. The differences
within each of the strata were consistent with
the overall comparison in that SIM-containing
drugs tended to be associated with a greater
likelihood of an XDDI.
The bivariate analyses of XDDIs involving
HCV medications after the addition of SIM- and
SOF-containing therapies are described in
Table 1. The variables associated with XDDIs
involving SIM-containing therapy were age,
weight, time since HCV diagnosis, total
number of home medications, and total
number of comorbidities. Specific home
medication classes associated with XDDI
involving SIM-containing therapy were
antipsychotics, antibiotics, antiepileptics, azole
antifungals, statins, calcium channel blockers,
corticosteroids, central nervous system (CNS)
depressants, erectile dysfunction drugs,
methadone, antiarrhythmic, corticosteroids,
alpha or muscarinic-3 blockers, and beta-2
agonists. Specific comorbidities associated with
XDDI involving SIM-containing therapy were
seizure disorder, arrhythmias, heart failure,
heart disease, chronic kidney disease,
recreational drug use, alcoholism, cancer,
dementia, chronic obstructive pulmonary
disorder, neuropathy, hypertension, organ
transplant, and anemia.
Fig. 1 Prevalence of contraindicated drug–drug interactions (XDDI) involving hepatitis C therapy after addition of simeprevir- and sofosbuvir-containing therapy
70 Infect Dis Ther (2015) 4:67–78
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T a b
l e 1 B i v a r i a t e a n a l y s e s o f c l i n i c a l a n d d e m o g r a p h i c c o v a r i a t e s
a s s o c i a t e d w i t h c o n t r a i n d i c a t e d d r u g – d r u g i n t e r a c t i o n s ( X D D I ) o c c u r r i n g w
i t h H C V t h e r a p y
a f t e r a d d i t i o n o f s i m e p r e v i r
- a n d s o f o s b u v i r - c o n t a i n i n g t h e r a p y
C o v a r i a t e
N o X D D I
a f t e r a d
d i t i o n
o f S I M
1
P R
( n 5
3 , 7
1 6 )
X D D I a f t e r
a d d i t i o n o
f
S I M
1
P R
( n 5
5 3 5 )
O d d s r a t i o
( 9 5 %
c o n
fi d e n c e i n t e r v a l
)
p
v a l u e
N o
X D D I
a f t e
r a
d d i t i o n
o f S O F 1
P R
( n 5
4 , 0
5 0 )
X D D I a f t e r
a d d i t i o n o
f
S O F 1
P R
( n 5
2 0 1 )
O d d s r a t i o
( 9 5 %
c o n
fi d e n
c e
i n t e r v a l )
p
v a l u e
A g e , m e a n ±
S D
5 9 . 7 ±
7 . 5
6 0 . 7 ±
8 . 3
1 . 0 2 ( 1 . 0 1 – 1 . 0 3 )
0 . 0 0 8
5 9 . 9 ±
7 . 6
5 8 . 8 ±
7 . 4
0 . 9 8 ( 0 . 9
6 – 1 . 0 0 )
0 . 0 5
M a l e s e x , n ( % )
3 , 5 9 3 ( 9 6 . 7 )
5 0 9 ( 9 5 . 1 )
1 . 4 9 ( 0 . 9 7 – 2 . 3 0 )
0 . 0 7
3 , 9 0 5 ( 9 6 . 4 )
1 9 7 ( 9 8 . 0 )
0 . 5 5 ( 0 . 2
0 – 1 . 5 0 )
0 . 3 2
R a c e , n ( % )
1 . 0 0 ( 0 . 9 2 – 1 . 1 0 )
0 . 3 1
0 . 9 1 ( 0 . 7
9 – 1 . 0 4 )
0 . 4 5
A f r i c a n A m e r i c a n
1 , 0 6 0 ( 2 8 . 5 )
1 5 9 ( 2 9 . 7 )
1 , 1 5 2 ( 2 8 . 4 )
6 7 ( 3 3 . 3 )
C a u c a s i a n
2 , 1 7 3 ( 5 8 . 5 )
3 0 3 ( 5 6 . 6 )
2 , 3 6 4 ( 5 8 . 4 )
1 1 2 ( 5 5 . 7 )
H i s p a n i c
1 0 8 ( 2 . 9 )
1 0 ( 1 . 9 )
1 1 4
( 2 . 8 )
4 ( 2 . 0 )
O t h e r / u n r e p o r t e d
3 7 5 ( 1 0 . 1 )
6 3 ( 1 1 . 8 )
4 2 0
( 1 0 . 4 )
1 8 ( 9 . 0 )
W e i g h t , m e a n ±
S D
8 7 . 4 ±
1 9 . 6
8 5 . 5 ±
2 2 . 0
1 . 0 0 ( 0 . 9 9 – 1 . 0 0 )
0 . 0 5
8 7 . 3 ?
1 9 . 8
8 6 . 1 ±
2 1 . 4
1 . 0 0 ( 0 . 9
9 – 1 . 0 0 )
0 . 4 0
T i m e s i n c e d i a g n o s i s o f H C
V ,
m e d i a n ( I Q R )
1 2 ( 8 – 1 4 )
1 2 ( 9 – 1 4 )
1 . 0 2 ( 1 . 0 0 – 1 . 0 4 )
0 . 0 0 7
1 2 ( 8 – 1 4 )
1 2 ( 9 – 1 4 )
1 . 0 2 ( 0 . 9
8 – 1 . 0 5 )
0 . 2 5
M e d i c a t i o n s
T o t a l n u m b e r o f h o m e
m e d i c a t i o n s , m e d i a n ( I Q R
)
7 ( 4 – 1 0 )
1 0 ( 7 – 1 4 )
1 . 1 4 ( 1 . 1 2 – 1 . 1 6 )
\ 0 . 0 0 1
7 ( 4 – 1 0 )
1 0 ( 7 – 1 4 )
1 . 1 2 ( 1 . 0
9 – 1 . 1 4 ) \ 0 . 0 0 1
U s e o f C 6 h o m e
m e d i c a t i o n s , n ( % )
2 , 1 7 1 ( 5 8 . 4 )
4 6 3 ( 8 6 . 5 )
4 . 5 8 ( 3 . 5 4 – 5 . 9 2 )
\ 0 . 0 0 1
2 , 4 6 2 ( 6 0 . 8 )
1 7 2 ( 8 5 . 6 )
3 . 8 3 ( 2 . 5
7 – 5 . 7 0 ) \ 0 . 0 0 1
A l p h a o r m u s c a r i n i c - 3
b l o c k e r , n ( % )
2 5 9 ( 7 . 0 )
5 4 ( 1 0 . 1 )
1 . 5 0 ( 1 . 1 0 – 2 . 0 4 )
0 . 0 1
2 2 5
( 5 . 6 )
8 8 ( 4 3 . 8 )
1 3 . 2 3
( 9 . 7 2 – 1
8 . 0 4 )
\ 0 . 0 0 1
A n t i a r r h y t h m i c s , n ( % )
5 9 ( 1 . 6 )
2 0 ( 3 . 7 )
2 . 4 1 ( 1 . 4 4 – 4 . 0 3 )
0 . 0 0 1
7 4 ( 1 . 8 )
5 ( 2 . 5 )
1 . 3 8 ( 0 . 5
5 – 3 . 4 3 )
0 . 5 0
A n t i b i o t i c s , n ( % )
7 ( 0 . 2 )
1 5 ( 2 . 8 )
1 5 . 2 8 ( 6 . 2 0 – 3 7 . 6 6 )
\ 0 . 0 0 1
1 9 ( 0 . 5 )
3 ( 1 . 5 )
3 . 2 2 ( 0
. 9 4 – 1
0 . 9 5 )
0 . 0 8
A n t i d e p r e s s a n t s , n ( % )
5 7 6 ( 1 5 . 5 )
9 1 ( 1 7 . 0 )
1 . 1 2 ( 0 . 8 8 – 1 . 4 2 )
0 . 3 7
6 1 1
( 1 5 . 1 )
5 6 ( 2 7 . 9 )
2 . 1 7 ( 1 . 5
8 – 2 . 9 9 ) \ 0 . 0 0 1
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T a b l e 1
c o n t i n u e d
C o v a r i a t e
N o X D D I
a f t e r a d
d i t i o n
o f S I M
1
P R
( n 5
3 , 7
1 6 )
X D D I a f t e r
a d d i t i o n o
f
S I M
1
P R
( n 5
5 3 5 )
O d d s r a t i o
( 9 5 %
c o n
fi d e n c e i n t e r v a l
)
p
v a l u e
N o
X D D I
a f t e
r a d
d i t i o n
o f S O F 1
P R
( n 5
4 , 0
5 0 )
X D D I a
f t e r
a d d i t i o n o
f
S O F 1
P R
( n 5
2 0 1 )
O d d s r a t i o
( 9 5 %
c o n
fi d e n
c e
i n t e r v a l )
p
v a l u e
A n t i e p i l e p t i c s , n ( % )
1 0 ( 0 . 3 )
1 2 0 ( 2 2 . 4 )
1 0 7 . 1 6 ( 5 5 . 7 7 – 2 0 5 . 9 0 ) \ 0 . 0 0 1
3 9 ( 1 . 0 )
9 1 ( 4 5 . 3 )
8 5 . 0 8
( 5 5 . 8 9 –
1 2 9 . 5 2 )
\ 0 . 0 0 1
A n t i p s y c h o t i c s , n ( % )
3 6 0 ( 9 . 7 )
1 0 0 ( 1 8 . 7 )
2 . 1 4 ( 1 . 6 8 – 2 . 7 3 )
\ 0 . 0 0 1
4 1 4
( 1 0 . 2 )
4 6 ( 2 2 . 9 )
2 . 6 1 ( 1 . 8
5 – 3 . 6 8 ) \ 0 . 0 0 1
A z o l e a n t i f u n g a l s , n ( % )
1 ( 0 . 0 )
1 3 ( 2 . 4 )
9 2 . 5 2 ( 1 2 . 0 8 – 7 0 8 . 7 0 ) \ 0 . 0 0 1
1 2 ( 0 . 3 )
2 ( 1 . 0 )
3 . 3 8 ( 0
. 7 5 – 1
5 . 2 1 )
0 . 0 9
B e t a - 2 a g o n i s t s , n ( % )
1 5 ( 0 . 4 )
5 ( 0 . 9 )
2 . 5 0 ( 0 . 9 0 – 6 . 9 5 )
0 . 0 7
1 9 ( 0 . 5 )
0 ( 0 )
N A
1 . 0 0
C a l c i u m c h a n n e l b l o c k e r s ,
n ( % )
5 0 4 ( 1 3 . 6 )
2 0 6 ( 3 8 . 5 )
3 . 9 9 ( 3 . 2 7 – 4 . 8 6 )
\ 0 . 0 0 1
6 7 4
( 1 6 . 6 )
3 6 ( 1 7 . 9 )
1 . 0 9 ( 0 . 7
6 – 0 . 9 9 )
0 . 6 4
C N S d e p r e s s a n t s , n ( % )
1 , 2 2 3 ( 3 2 . 9 )
2 2 2 ( 4 1 . 5 )
1 . 4 4 ( 1 . 2 0 – 1 . 7 4 )
\ 0 . 0 0 1
1 , 3 6 3 ( 3 3 . 7 )
8 2 ( 4 0 . 8 )
1 . 3 6 ( 1 . 0
2 – 1 . 8 1 )
0 . 0 4
C o r t i c o s t e r o i d s , n ( % )
5 7 9 ( 1 5 . 6 )
2 0 4 ( 3 8 . 1 )
3 . 3 4 ( 2 . 7 5 – 4 . 0 6 )
\ 0 . 0 0 1
7 1 3
( 1 7 . 6 )
7 0 ( 3 4 . 8 )
2 . 5 0 ( 1 . 8
5 – 3 . 3 8 ) \ 0 . 0 0 1
E r e c t i l e d y s f u n c t i o n d r u g s ,
n ( % )
7 7 5 ( 2 0 . 9 )
8 9 ( 1 6 . 6 )
0 . 7 6 ( 0 . 6 0 – 0 . 9 6 )
0 . 0 2
8 1 6
( 2 0 . 1 )
4 8 ( 2 3 . 9 )
1 . 2 4 ( 0 . 8
9 – 1 . 7 4 )
0 . 2 0
S t a t i n s , n ( % )
6 5 0 ( 1 7 . 5 )
1 1 7 ( 2 1 . 9 )
1 . 3 2 ( 1 . 0 6 – 1 . 6 5 )
0 . 0 1
7 2 1
( 1 7 . 8 )
4 6 ( 2 2 . 9 )
1 . 3 7 ( 0 . 9
8 – 1 . 9 2 )
0 . 0 7
C o m o r b i d i t i e s
T o t a l n u m b e r o f
c o m o r b i d i t i e s , m e d i a n ( I Q
R )
7 ( 5 – 1 0 )
8 ( 6 – 1 1 )
\ 0 . 0 0 1
7 ( 5 – 1 0 )
8 ( 6 – 1 1 )
0 . 0 0 1
C o m o r b i d i t i e s C 1 0 , n ( %
)
9 9 7 ( 2 6 . 8 )
2 0 1 ( 3 7 . 6 )
1 . 6 4 ( 1 . 3 6 – 1 . 9 8 )
\ 0 . 0 0 1
1 , 1 2 1 ( 2 7 . 7 )
7 7 ( 3 8 . 3 )
1 . 6 2 ( 1 . 2
1 – 2 . 1 7 )
0 . 0 0 1
A l c o h o l i s m , n ( % )
1 , 4 7 7 ( 3 9 . 7 )
1 8 9 ( 3 5 . 3 )
0 . 8 3 ( 0 . 6 9 – 1 . 0 0 )
0 . 0 5
1 , 5 8 0 ( 3 9 . 0 )
8 6 ( 4 2 . 8 )
1 . 1 7 ( 0 . 8
8 – 1 . 5 6 )
0 . 2 9
A n e m i a , n ( % )
3 9 1 ( 1 0 . 5 )
8 8 ( 1 6 . 4 )
1 . 6 7 ( 1 . 3 0 – 2 . 1 5 )
\ 0 . 0 0 1
4 5 8
( 1 1 . 3 )
2 1 ( 1 0 . 4 )
0 . 9 2 ( 0 . 5
8 – 1 . 4 5 )
0 . 7 1
A n x i e t y , n ( % )
6 1 4 ( 1 6 . 5 )
7 5 ( 1 4 . 0 )
0 . 8 2 ( 0 . 6 4 – 1 . 0 7 )
0 . 1 4
6 6 0
( 1 6 . 3 )
2 9 ( 1 4 . 4 )
0 . 8 7 ( 0 . 5
8 – 1 . 3 0 )
0 . 4 8
A r r h y t h m i a s , n ( % )
1 6 3 ( 4 . 4 )
4 6 ( 8 . 6 )
2 . 0 5 ( 1 . 4 6 – 2 . 8 8 )
\ 0 . 0 0 1
2 0 3
( 5 . 0 )
6 ( 3 . 0 )
0 . 5 8 ( 0 . 2
6 – 1 . 3 3 )
0 . 1 9
A s t h m a , n ( % )
1 7 7 ( 4 . 8 )
2 8 ( 5 . 2 )
1 . 1 0 ( 0 . 7 3 – 1 . 6 6 )
0 . 6 4
1 9 6
( 4 . 8 )
9 ( 4 . 5 )
0 . 9 2 ( 0 . 4
7 – 1 . 8 3 )
0 . 8 2
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T a b l e 1
c o n t i n u e d
C o v a r i a t e
N o X D D I
a f t e r a d
d i t i o n
o f S I M
1
P R
( n 5
3 , 7
1 6 )
X D D I a
f t e r
a d d i t i o n o
f
S I M
1
P R
( n 5
5 3 5 )
O d d s r a t i o
( 9 5 %
c o n
fi d e n c e i n t e r v a l
)
p
v a l u e
N o
X D D I
a f t e r a d
d i t i o n
o f S O F 1
P R
( n 5
4 , 0
5 0 )
X D D I a f t e r
a d d i t i o n o
f
S O F 1
P R
( n 5
2 0 1 )
O d d s r a
t i o
( 9 5 %
c o n
fi d e n
c e
i n t e r v a l )
p
v a l u e
B i p o l a r , m o o d o r p e r s o n a l i t y
d i s o r d e r , n ( % )
4 4 1 ( 1 1 . 9 )
7 9 ( 1 4 . 8 )
1 . 2 9 ( 0 . 9 9 – 1 . 6 7 )
0 . 0 6
4 8 5
( 1 2 . 0 )
3 5 ( 1 7 . 4 )
1 . 5 5 ( 1 . 0
6 –
2 . 2 6 )
0 . 0 2
C a n c e r , n ( % )
4 9 5 ( 1 3 . 3 )
1 2 5 ( 2 3 . 4 )
1 . 9 8 ( 1 . 5 9 – 2 . 4 8 )
\ 0 . 0 0 1
5 8 3
( 1 4 . 4 )
3 7 ( 1 8 . 4 )
1 . 3 4 ( 0 . 9
3 – 1 . 9 4 )
0 . 1 1
C h r o n i c k i d n e y d i s e a s e , n ( % ) 1 7 9 ( 4 . 8 )
6 6 ( 1 2 . 3 )
2 . 7 8 ( 2 . 0 6 – 3 . 7 5 )
\ 0 . 0 0 1
2 3 5
( 5 . 8 )
1 0 ( 5 . 0 )
0 . 8 5 ( 0 . 4
4 – 1 . 6 3 )
0 . 6 2
C i r r h o s i s , n ( % )
4 1 5 ( 1 1 . 2 )
6 2 ( 1 1 . 6 )
1 . 0 4 ( 0 . 7 9 – 1 . 3 9 )
0 . 7 7
4 6 3
( 1 1 . 4 )
1 4 ( 7 . 0 )
0 . 5 8 ( 0 . 3
3 – 1 . 0 0 )
0 . 0 5
C h r o n i c o b s t r u c t i v e
p u l m o n a r y d i s o r d e r , n ( % )
5 2 5 ( 1 4 . 1 )
1 0 3 ( 1 9 . 3 )
1 . 4 5 ( 1 . 1 5 – 1 . 8 3 )
0 . 0 0 2
5 9 9
( 1 4 . 8 )
2 9 ( 1 4 . 4 )
0 . 9 7 ( 0 . 6
5 – 1 . 4 5 )
0 . 8 8
D e m e n t i a , n ( % )
4 9 ( 1 . 3 )
1 5 ( 2 . 8 )
2 . 1 6 ( 1 . 2 0 – 3 . 8 8 )
0 . 0 0 8
5 9 ( 1 . 5 )
5 ( 2 . 5 )
1 . 7 3 ( 0 . 6
9 – 4 . 3 5 )
0 . 2 4
D e p r e s s i o n , n ( % )
1 , 5 4 9 ( 4 1 . 7 )
2 0 8 ( 3 8 . 9 )
0 . 8 9 ( 0 . 7 4 – 1 . 0 7 )
0 . 2 2
1 , 6 5 4 ( 4 0 . 8 )
1 0 3 ( 5 1 . 2 )
1 . 5 2 ( 1 . 1
5 – 2 . 0 2 )
0 . 0 0 3
D i a b e t e s , n ( % )
9 9 2 ( 2 6 . 7 )
1 6 0 ( 2 9 . 9 )
1 . 1 7 ( 0 . 9 6 – 1 . 4 3 )
0 . 1 2
1 , 1 0 0 ( 2 7 . 2 )
5 2 ( 2 5 . 9 )
0 . 9 4 ( 0 . 6
8 – 1 . 2 9 )
0 . 6 9
D y s l i p i d e m i a , n ( % )
1 , 3 5 1 ( 3 6 . 4 )
2 1 1 ( 3 9 . 4 )
1 . 1 4 ( 0 . 9 5 – 1 . 3 7 )
0 . 1 7
1 , 4 9 2 ( 3 6 . 8 )
7 0 ( 3 4 . 8 )
0 . 9 2 ( 0 . 6
8 – 1 . 2 3 )
0 . 5 6
E p i l e p s y o r o t h e r s e i z u r e
d i s o r d e r , n ( % )
1 1 5 ( 3 . 1 )
7 6 ( 1 4 . 2 )
5 . 1 9 ( 3 . 8 2 – 7 . 0 4 )
\ 0 . 0 0 1
1 2 7
( 3 . 1 )
6 4 ( 3 1 . 8 )
1 4 . 4 3
( 1 0 . 2 2 –
2 0 . 3 8 )
\ 0 . 0 0 1
E r e c t i l e d y s f u n c t i o n , n ( %
)
8 5 7 ( 2 3 . 1 )
1 2 5 ( 2 3 . 4 )
1 . 0 2 ( 0 . 8 2 – 1 . 2 6 )
0 . 8 8
9 2 5
( 2 2 . 8 )
5 7 ( 2 8 . 4 )
1 . 3 4 ( 1 . 0
0 – 1 . 0 3 )
0 . 0 7
G a s t r o i n t e s t i n a l r e fl u x d i s e a s e ,
n ( % )
9 0 7 ( 2 4 . 4 )
1 4 1 ( 2 6 . 4 )
1 . 1 1 ( 0 . 9 0 – 1 . 3 6 )
0 . 3 3
1 , 0 0 0 ( 2 4 . 7 )
4 8 ( 2 3 . 9 )
0 . 9 6 ( 0 . 6
9 – 1 . 3 3 )
0 . 8 0
H e a r t d i s e a s e , n ( % )
6 2 8 ( 1 6 . 9 )
1 1 2 ( 2 0 . 9 )
1 . 3 0 ( 1 . 0 4 – 1 . 6 3 )
0 . 0 2
7 0 4
( 1 7 . 4 )
3 6 ( 1 7 . 9 )
1 . 0 4 ( 0 . 7
2 – 1 . 5 0 )
0 . 8 5
H e a r t f a i l u r e , n ( % )
1 1 0 ( 3 . 0 )
3 0 ( 5 . 6 )
1 . 9 5 ( 1 . 2 9 – 2 . 9 5 )
0 . 0 0 1
1 3 3
( 3 . 3 )
7 ( 3 . 5 )
1 . 0 6 ( 0 . 4
9 – 2 . 3 0 )
0 . 8 8
H e p a t i t i s B , n ( % )
1 7 5 ( 4 . 7 )
3 2 ( 6 . 0 )
1 . 2 9 ( 0 . 8 7 – 1 . 9 0 )
0 . 2 0
1 9 6
( 4 . 8 )
1 1 ( 5 . 5 )
1 . 1 4 ( 0 . 6
1 – 2 . 1 3 )
0 . 6 8
H i s t o r y o f m y o c a r d i a l
i n f a r c t i o n , n ( % )
8 6 ( 2 . 3 )
7 ( 1 . 3 )
0 . 5 6 ( 0 . 2 6 – 1 . 2 2 )
0 . 1 4
9 1 ( 2 . 2 )
2 ( 1 . 0 )
0 . 4 4 ( 0 . 1
1 – 1 . 7 9 )
0 . 2 4
H o m e l e s s , n ( % )
2 4 3 ( 6 . 5 )
2 8 ( 5 . 2 )
0 . 7 9 ( 0 . 5 3 – 1 . 1 8 )
0 . 2 5
2 5 5
( 6 . 3 )
1 6 ( 8 . 0 )
1 . 2 9 ( 0 . 7
6 – 2 . 1 8 )
0 . 3 5
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T a b l e 1
c o n t i n u e d
C o v a r i a t e
N o X D D I
a f t e r a
d d i t i o n
o f S I M
1
P R
( n 5
3 , 7
1 6 )
X D D I a f t e r
a d d i t i o n o
f
S I M
1
P R
( n 5
5 3 5 )
O d d s r a t i o
( 9 5 %
c o n
fi d e n c e i n t e r v a l
)
p
v a l u e
N o
X D D I
a f t e
r a d
d i t i o n
o f S O F 1
P R
( n 5
4 , 0
5 0 )
X D D I a
f t e r
a d d i t i o n o
f
S O F 1
P R
( n 5
2 0 1 )
O d d s r a t i o
( 9 5 %
c o n
fi d e n
c e
i n t e r v a l )
p
v a l u e
H y p e r t e n s i o n , n ( % )
2 , 0 9 7 ( 5 6 . 4 )
3 3 9 ( 6 3 . 4 )
1 . 3 4 ( 1 . 1 1 – 1 . 6 1 )
0 . 0 0 2
2 , 3 2 1 ( 5 7 . 3 )
1 1 5 ( 5 7 . 2 )
1 . 0 0 ( 0 . 7
5 – 1 . 0 1 )
0 . 9 8
I n s o m n i a o r o t h e r s l e e p
d i s o r d e r s , n ( % )
4 9 9 ( 1 3 . 4 )
7 3 ( 1 3 . 6 )
1 . 0 2 ( 0 . 7 8 – 1 . 3 3 )
0 . 8 9
5 4 9
( 1 3 . 6 )
2 3 ( 1 1 . 4 )
0 . 8 2 ( 0 . 5
3 – 1 . 2 8 )
0 . 3 9
M e t h a d o n e , n ( % )
6 8 ( 1 . 8 )
1 8 ( 3 . 4 )
1 . 8 7 ( 1 . 1 0 – 3 . 1 7 )
0 . 0 2
8 1 ( 2 . 0 )
5 ( 2 . 5 )
1 . 2 5 ( 0 . 5
0 – 3 . 1 2 )
0 . 6 3
N e u r o p a t h y , n ( % )
4 2 5 ( 1 1 . 4 )
7 8 ( 1 4 . 6 )
1 . 3 2 ( 1 . 0 2 – 1 . 7 2 )
0 . 0 4
4 6 6
( 1 1 . 5 )
3 7 ( 1 8 . 4 )
1 . 7 4 ( 1 . 2
0 – 2 . 5 1 )
0 . 0 0 3
O r g a n t r a n s p l a n t , n ( % )
3 3 ( 0 . 9 )
2 7 ( 5 . 0 )
5 . 9 3 ( 3 . 5 4 – 9 . 9 5 )
\ 0 . 0 0 1
5 8 ( 1 . 4 )
2 ( 1 . 0 )
0 . 6 9 ( 0 . 1
7 – 2 . 8 5 )
1 . 0 0
O s t e o p o r o s i s , o s t e o a r t h r i t i s o r
o s t e o g e n e s i s , n ( % )
7 7 6 ( 2 0 . 9 )
1 2 7 ( 2 3 . 7 )
1 . 1 8 ( 0 . 9 5 – 1 . 4 6 )
0 . 1 3
8 6 5
( 2 1 . 4 )
3 8 ( 1 8 . 9 )
0 . 8 6 ( 0 . 6
0 – 1 . 2 3 )
0 . 4 1
P e r i p h e r a l v a s c u l a r d i s e a s e ,
n ( % )
2 3 9 ( 6 . 4 )
4 4 ( 8 . 2 )
1 . 3 0 ( 0 . 9 3 – 1 . 8 2 )
0 . 1 2
2 7 1
( 6 . 7 )
1 2 ( 6 . 0 )
0 . 8 9 ( 0 . 4
9 – 1 . 6 1 )
0 . 6 9
P o s t - t r a u m a t i c s t r e s s d i s o r
d e r ,
n ( % )
8 9 9 ( 2 4 . 2 )
1 2 7 ( 2 3 . 7 )
0 . 9 8 ( 0 . 7 9 – 1 . 2 1 )
0 . 8 2
9 3 6
( 2 3 . 1 )
9 0 ( 4 4 . 8 )
2 . 7 0 ( 2 . 0
2 – 3 . 6 0 ) \ 0 . 0 0 1
P r o s t a t e d i s e a s e , n ( % )
6 2 7 ( 1 6 . 9 )
1 0 1 ( 1 8 . 9 )
1 . 1 5 ( 0 . 9 1 – 1 . 4 5 )
0 . 2 5
6 9 2
( 1 7 . 1 )
3 6 ( 1 7 . 9 )
1 . 0 6 ( 0 . 7
3 – 1 . 5 3 )
0 . 7 6
R e c r e a t i o n a l d r u g u s e , n ( % )
2 , 5 7 6 ( 6 9 . 3 )
3 2 9 ( 6 1 . 5 )
0 . 7 1 ( 0 . 5 9 – 0 . 8 5 )
\ 0 . 0 0 1
2 , 7 5 8 ( 6 8 . 1 )
1 4 7 ( 7 3 . 1 )
1 . 2 8 ( 0 . 9
3 – 1 . 7 5 )
0 . 1 3
S c h i z o p h r e n i a o r p s y c h o s i s ,
n ( % )
2 6 9 ( 7 . 2 )
4 4 ( 8 . 2 )
1 . 1 5 ( 0 . 8 2 – 1 . 6 0 )
0 . 4 2
2 9 4
( 7 . 3 )
1 9 ( 9 . 5 )
1 . 3 3 ( 0 . 8
2 – 2 . 1 7 )
0 . 2 5
T h y r o i d d i s e a s e , n ( % )
2 7 7 ( 7 . 5 )
4 4 ( 8 . 2 )
1 . 1 1 ( 0 . 8 0 – 1 . 5 5 )
0 . 5 3
3 1 0
( 7 . 7 )
1 1 ( 5 . 5 )
0 . 7 0 ( 0 . 3
8 – 1 . 3 0 )
0 . 2 5
T r a n s i e n t i s c h e m i c a t t a c k
o r
o t h e r c a r d i o v a s c u l a r h i s t o r y ,
n ( % )
1 5 2 ( 4 . 1 )
3 1 ( 5 . 8 )
1 . 4 4 ( 0 . 9 7 – 2 . 1 5 )
0 . 0 7
1 7 1
( 4 . 2 )
1 2 ( 6 . 0 )
1 . 4 4 ( 0 . 7
9 – 2 . 6 3 )
0 . 2 3
D a t a p r e s e n t e d a r e r e s t r i c t e
d t o X D D I s i n v o l v i n g S I M - o r S O F - c
o n t a i n i n g r e g i m e n s a n d n o t u n d e r l y i n g X D D I s i n v o l v i n g p a t i e n t s ’ h o m e m e d i c a t i o n s . A l l d a t a
p r e s e n t e d a s n ( % ) , m e d i a n
( i n t e r q u a r t i l e r a n g e ) a n d m e a n ±
s t a n
d a r d d e v i a t i o n u n l e s s o t h e r w i s e i n d i c a t e d
S I M ?
P R s i m e p r e v i r ? p e
g y l a t e d i n t e r f e r o n a n d r i b a v i r i n ,
S O F
?
P R s o f o s b u v i r ?
p e g y l a t e d i n t e r f e r o n a n d r i b a v i r i n ,
I Q R i n t e r q u a r t i l e r a n g e ,
S D s t a n d a r d
d e v i a t i o n ,
X D D I c o n t r a i n d i c a t e d d r u g – d r u g i n t e r a c t i o n
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Fewer variables were significantly associated
with XDDI involving SOF-containing therapy.
These included age, total number of home
medications, antipsychotics, antidepressants,
antiepileptic drugs, CNS depressants,
corticosteroids, alpha or muscarinic-3 blocker,
total number of comorbidities, bipolar/mood/
personality disorder, depression, seizure disorder,
post-traumatic stress disorder, neuropathy, and
cirrhosis. The use of C6 home medications and
having C10 comorbidities was associated with an
increased frequency of XDDI involving either
SIM- or SOF-containing therapy.
In multivariable analyses examining the
predictors of XDDIs involving SIM-containing
therapy, the only medication-related predictor
was use of C6 home medications (odds ratio OR
4.58, 95% confidence interval CI 3.54–5.20,
p\0.001). Similarly, the use of C6 home
medications was also the only variable
associated with an increased probability of
XDDI involving SOF-containing therapy (OR
3.83, 95% CI 2.57–5.70, p\0.001). To make the
models more specific, the use of C6 home
medications was replaced with the medication
classes associated with XDDI involving either
SIM- or SOF-containing therapy. The results of
these refined multivariable models are displayed
in Table 2. Variables independently associated
with XDDI involving SIM-containing therapy
were calcium channel blockers, corticosteroids,
antipsychotics, antiarrhythmic, and CNS
depressants. Variables independently
associated with XDDIs involving SOF-
containing therapy were corticosteroids,antipsychotics, antidepressants, and statins.
DISCUSSION
Therapies containing SIM or SOF are associated
with a high cost and it is imperative that
clinicians take appropriate measures to ensure
that patients have the highest likelihood of
completing therapy, achieving a sustained
virologic response and minimizing adverse
events [13]. In some situations, adverse events
that are a function of XDDIs can be prevented
by proactively identifying patients at risk for
XDDIs prior to prescribing SIM or SOF-
containing therapy and choosing the type of
therapy that is associated with a lower
probability or using them in patients who do
not have risk factors for XDDIs [14]. This
intervention, coupled with optimal drug
adherence, can contribute to the probability of a good treatment outcome.
The majority of other population-based
drug–drug interaction studies have been
focused on patients with HIV/HCV coinfection
[9, 10]. The present study, one of the largest
population-based drug–drug interaction studies,
focused on patients with HCV monoinfection.
Table 2 Variables independently associated withcontraindicated drug–drug interactions after the additionof simeprevir- or sofosbuvir-containing hepatitis C therapy
Variable Oddsratio
95%confidence
interval
p value
XDDI after addition of simeprevir-containing therapy
Calcium channel
blockers
4.15 3.38–5.11 \0.001
Corticosteroids 3.41 2.78–4.19 \0.001
Antipsychotics 2.53 1.96–3.28 \0.001
Antiarrhythmics 2.23 1.28–3.89 0.005
Central nervous
system depressants
1.32 1.09–1.61 0.005
XDDI after addition of sofosbuvir-containing therapy
Corticosteroids 2.54 1.87–3.44 0.001
Antipsychotics 2.44 1.71–3.48 0.001
Antidepressants 1.90 1.37–2.64 0.001
Statins 1.40 1.00–1.97 0.05
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The results presented here are consistent with
other publications [4, 9, 10, 15]. It was observed
that polypharmacy was an issue among patients
with HCV monoinfection and these patients are
vulnerable to the effects of XDDI. Patients in
the study were using a median of seven home
medications, and over 15% of patients had
XDDIs involving medications that they were
already taking and before the addition of SIM-
or SOF-containing therapy. This is important
because several other patient populations (HIV,
transplant, dialysis, etc.) are considered high
risk for XDDIs and now, given these data,
patients with HCV monoinfection should be
considered as well [15–18].
Patients with HCV monoinfection may need
pharmacotherapeutic intervention to resolve
any existing XDDIs before being prescribed
SIM- or SOF-containing therapy. It was also
observed that SIM-containing regimens were
associated with nearly triple the likelihood of
XDDIs compared to SOF-containing regimens.
These results are plausible given that SIM is a
CYP3A hepatic substrate and intestinal
inhibitor [1]. There may be altered exposure of
both SIM and other drugs that also utilize these
enzymatic pathways when used concomitantly
[1]. Conversely, SOF is metabolized by
P-glycoprotein (P-gp), a less ubiquitously
utilized metabolic pathway, and SOF exposure
may be altered in the presence of other P-gp
inducers/inhibitors [2]. Many XDDIs involving
either type of HCV therapy were predicted by
use of various drug classes. These data
demonstrate the need for a pharmacist toreview patients’ medications before HCV
therapy is prescribed.
To appropriately interpret these data, the
following considerations should be kept in
mind. First, exposure to SIM- and SOF-
containing HCV therapy was completely
theoretical. No patients in the study actually
received SIM- or SOF-containing therapy.
Rather, SIM- and SOF-containing therapy was
added to the home medication lists of the
patients in the study to assess what proportion
would have an XDDI if either of these regimens
were prescribed. This is strength of the paper,
because it demonstrates how a counterfactual
study design allows the evaluation of an
outcome of interest in the same patient under
two exposure conditions. Second, patients with
HIV were excluded because antiretroviral
therapy is an exceptionally strong predictor of
drug–drug interactions [11]. Apart from the use
of anti-retrovirals, it was also unclear if
medication use patterns differed between
coinfected and monoinfected patients. Because
of these issues, it was felt that inclusion of
patients with HIV/HCV coinfection would mask
some of the non-HIV-related predictors of XDDI
involving SIM- or SOF-containing therapy. To
preserve internal validity, the choice to restrict
the study population to only those with HCV
monoinfection was made. Third, liver
performance [fibrosis/alanine transaminase
(ALT), etc.] was not known and this, as well as
other markers or disease severity, may be
associated with higher medication use and
subsequent risk of XDDIs. Future studies
should attempt to assess the contribution of
markers of disease severity and determine if
variables such as time since HCV diagnosis are
truly associated with a higher probability of
medication use and XDDIs. Fourth, some of the
predictors, particularly for XDDI involving SOF-
containing therapy, are not drug classes that arecontraindicated with SOF-containing therapy in
the product labeling [2]. It is important to note
that patients receiving these drug classes were
more likely to have an XDDI involving SOF-
containing therapy, although these classes are
contraindicated themselves. More than likely,
these predictors may be indicative of XDDIs
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that may exist prior to the addition of HCV
therapy or a proxy for other variables such as
disease severity, whereby patients may require
the use of several medications to control other
underlying comorbidities. Finally, the hepatitis
C armamentarium is changing rapidly. The
regimens we evaluated contained interferon
and ribavirin in combination with either SIM
or SOF. Future HCV treatment regimens may
not contain some or all of these components. It
is important to note that interferon and
ribavirin are associated with few XDDIs and
the majority of interactions were driven in large
part due to SIM or SOF. This study will need to
be repeated in the future with emerging agents
like ledipasvir, ombitasvir, dasabuvir, and
daclatasvir.
CONCLUSION
In summary, the results of this study found that
HCV monoinfected patients are at high risk for
XDDIs, and SOF-containing therapy had a lower
frequency of XDDIs than SIM-containing
therapy. Polypharmacy with various classes of home medications predicted XDDIs involving
SIM- or SOF-containing therapy. Clinicians
prescribing either of these treatment regimens
should thoroughly evaluate patients’ existing
medications to avoid potential XDDIs.
ACKNOWLEDGMENTS
This material is based upon work partially
supported by the Office of Research and
Development, Department of Veterans Affairs.
This article has greatly benefited from the
thoughtful editing of Allison Krug and the
data entry of Michael Veve.
No funding or sponsorship was received for
this or publication of this article.
All named authors meet the ICMJE criteria
for authorship for this manuscript, take
responsibility for the integrity of the work as a
whole, and have given final approval for the
version to be published.
Conflict of interest. Mona Nasiri, Arden
Koroglu, Steven Bliss, Melissa Davis, Louise-
Anne McNutt, and Christopher Miller declare
that they have no conflicts of interest.
Dr. Patel has received research grant support
for other studies from Gilead Sciences. Dr. Patel
owns five shares of stock in Gilead Sciences.
Compliance with ethics. This article does
not contain any new studies with human or
animal subjects performed by any of the
authors.
Open Access. This article is distributed
under the terms of the Creative Commons
Attribution Noncommercial License which
permits any noncommercial use, distribution,
and reproduction in any medium, provided the
original author(s) and the source are credited.
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