Introduction:

Hepatitis C, Substance Use,
and Dependence

Illicit drug and alcohol abuse and dependence are problems
of major medical importance in the United States, leading
to high rates of morbidity and mortality from end-stage
liver disease. The prevalence of illicit drug use in the United
States, as estimated by the National Survey on Drug Use
and Health in 2002, stands at 19.5 million Americans above
the age of 12; half of Americans aged 12 or older (51.0%)
reported being current drinkers of alcohol, an estimated
120 million people [1•].

Salient illicit drug use and practices
are presented in Table 1. The Centers for Disease Control
has estimated that 60% of all new cases of hepatitis C are
related to injection drug use [2]. Injection drug practices
include the use of heroin, cocaine, methamphetamine, and
prescription opioids (Table 1).

It has been estimated that
there are at least 800,000 untreated injection-heroin users
[3]. However, the population of opioid-drug users may be
grossly undercounted, because some surveys have found up
to three times more illicit drug users in particular regions
than commonly estimated [4].
Drug addiction is a chronic, relapsing neurophysiologic
disease resulting from the prolonged neurologic
effects of drugs. The neurochemical abnormalities resulting
from chronic use, such as opioids, underlie many of the
observed physical and behavioral aspects of addiction
(Table 1). The brain abnormalities associated with addiction
are wide ranging, complex, and long lasting [5,6].

They can involve genetically abnormal brain signaling
pathways, social factors, psychological conditioning or
stress, and result in cravings leading to a predisposition to
relapse even months or years after drug use cessation.
Recent studies have identified risk factors for the transition
to injection drug use that include the following: emerging
drug practices, differential characteristics of opiate injectors
versus inhalers, and patient-related factors that predict
entry into substance abuse treatment [7•,8].

The importance
of limiting individuals from progressing to injection
drug use can be vividly seen from data comparing the
hepatitis C incidence between injection and noninjection
drug users [9]. This longitudinal surveillance study in
New York City showed an annual incidence rate of
hepatitis C in young noninjection drug users of 0.4 per 100
person-years compared with 35.9 per 100 person-years in
injection drug users (IDUs).

Thus, delaying or preventing
the transition to injection drug use can have a significant
health benefit by reducing the risk of comorbid conditions
associated with substance abuse and addiction.

read the full file here: 002_HP04-3-1-05