for hepatitis C virus (HCV) was associated with reduced drug use, especially
among those who tested positive, but even people who tested negative saw some reduction, according
to study results presented at the 2017 AASLD Liver Meeting this week in Washington,
simple act of testing can have an important effect on risk behaviour," Hooman Farhang Zangneh of Toronto
General Hospital said at an AASLD press briefing.
HCV is readily transmitted through shared needles and
people who inject drugs have high rates of HCV incidence (new infections) and
prevalence (total existing infections). HCV prevention and treatment for
current and former drug users was a key theme at the conference, especially in
the context of growing opioid epidemics in North America and elsewhere.
People who inject drugs make up a large proportion of
those living with hepatitis C – and of those who will need to be treated in
order to eliminate HCV as a public health threat. However, many of these
individuals have not been tested and do not know their HCV status. Addiction
treatment programmes, such as those that provide opioid substitution therapy
(OST) using methadone or buprenorphine, offer a potential entry point into
hepatitis C care.
Zangneh and colleagues performed a retrospective
analysis to assess the effect of HCV diagnosis on substance use behaviour,
using electronic health records from a network of 47 addiction treatment
clinics in Ontario from 2007 through 2013. Ontario has more than 50,000 people receiving OST, with an HCV prevalence
approaching 65% among opioid injectors, Zangneh noted as background.
The researchers identified 2406 individuals who were
screened for HCV infection during the study period and had available urine test
results to monitor drug use. Just over 60% were men and the average age was
about 40 years. About 85% resided in cities and about 15% in rural areas. Among the screened participants, 527 (22%)
tested positive for HCV antibodies.
Zangneh's team looked at the proportion of urine
samples testing positive for drug use in the year after HCV testing compared
with the year prior to testing. Study participants diagnosed with HCV had a
statistically significant 8.1% reduction in urine samples showing
non-prescription opioid use. Those found to be HCV-negative had a smaller but
still significant 6.7% decrease.
After adjusting for other factors in a multivariate
analysis, people who tested HCV positive were 33% more likely to lower their
use of non-prescription opioids, as compared with those who tested HCV
negative. People diagnosed with HCV were
also about 50% more likely to decrease their use of benzodiazepines and
cocaine. Reducing use of these non-injected drugs might help improve retention
in OST programmes, Zangneh suggested.
"Patients diagnosed with HCV
reduced their non-prescription drug use, including benzodiazepines and cocaine,
in the year following diagnosis," the researchers concluded. "This highlights the importance of screening individuals in OST for HCV,
as this alone may have a positive impact on their drug use activity."
testing of people who inject drugs "may reduce health consequences for the
individual and reduce transmission in the community," Zangneh told
reporters. He suggested that further research should be done to see if the
effect of testing on drug use behaviour extends to other infectious diseases.