Hepatitis C treatment completion and
response rates among injecting drug users are similar to those seen in general
patient populations, the findings of a meta-analysis published in the online
edition of Clinical Infectious Diseases
show. The best outcomes were seen in people who received therapy and support for
their addiction.
“The availability of support services
during HCV [hepatitis C virus] treatment significantly increased the treatment
completion rates among drug users,” comment the authors.
Infection with genotypes 1 and 4 and
co-infection with HIV were associated with lower completion and response rates.
In resource-rich settings such as the
United States and Europe, injecting drug users are the group most affected by
hepatitis C. Uptake of therapy for the infection is low in this population,
with less than a fifth of those evaluated actually starting treatment.
Recent improvements in hepatitis C therapy
mean that an increasing number of people can be cured. Understanding the
factors associated with treatment completion and response rates will mean that
services can be tailored to meet the needs of injecting drug users so they can
benefit from the directly acting anti-hepatitis C drugs which are becoming
available.
Investigators therefore designed a
meta-analysis of hepatitis C treatment studies that involved ten or more
injecting drug users and reported on completion and success rates.
“Since most of these studies have
relatively small sample sizes, their aggregation through meta-analysis increases
statistical power and facilitates generation of evidence-based conclusions,”
write the investigators.
A total of 34 studies involving 2866 people met the investigators’ inclusion criteria. The studies were all
published between 2004 and 2011, their sample size ranging from eleven to 822
individuals.
All the patients had a history of illicit
drug use, with approximately 38% being active users. Over three-quarters (77%)
were male, and their median age was 38 years.
Hepatitis C therapy consisted of pegylated
interferon and ribavirin. Treatment was completed by 83% of patients. The
authors note that this completion rate was comparable to that seen in clinical
trials, which excluded current drug users, conducted during the development of
pegylated interferon/ribavirin therapy.
Findings of the meta-analysis showed that
the higher the proportion of people who received treatment for addiction, the
higher the completion rate for therapy (p < 0.001). There was
non-significant evidence that the rate of treatment completion was increased by
the provision of substitution therapy (p = 0.058).
The completion rate for people infected
with genotypes 1 or 4 was 80%. This compared to a rate of 90% for individuals with genotype 2 or 3 infection. Treatment was completed by 87% of people
with hepatitis C mono-infection, but by just 68% of those co-infected with HIV
and hepatitis C.
Support services significantly improved the
chances of treatment completion (p < 0.001), whereas HIV co-infection (p
< 0.001) and male gender (p < 0.001) were both associated with reduced likelihood of completing a course of therapy.
An undetectable hepatitis C viral load 24
weeks after the completion of therapy (sustained virological response; SVR) was
considered a treatment response. The response rate among people who received
treatment for their drug addiction was 53%. This response rate is similar to
that seen in the overall population of people receiving treatment for chronic
hepatitis C with pegylated interferon/ribavirin.
Response rates were poorer for those with
genotype 1 or 4 infection compared to people infected with genotypes 3 or 4
(45 vs 70%). SVR rates were also lower among people co-infected with HIV
compared to people with hepatitis C mono-infection (41 vs 58%).
Support during treatment from a
multi-disciplinary team was associated with better chances of achieving a
treatment response (p < 0.001).
“Published data suggest that the overall
rates for treatment completion and SVR for [pegylated interferon/ribavirin]-treated
drug users are comparable to registration trials,” conclude the researchers.
“We recommend that drug users treated for addiction should be considered for
HCV treatment under the same circumstances as the non-drug users.”