Abstract Addiction to opioid analgesics is an important and
yet underinvestigated clinical issue, which has substantial
implications in opioid therapy for chronic pain management.
Problematic opioid use, including compulsive opioid seeking
and addiction, arises in some fraction of opioid-treated
chronic pain patients. The connection between chronic pain
and opioid addiction is a complex interplay between
psychological, epidemiological, and neurobiological factors.
Herein, we explore this critical relationship.
Keywords Opioids . Abuse . Addiction . Aberrant drug
related behavior (ADRB) . Chronic pain . Epidemiology .
Neurobiology . Cellular mechanisms
Introduction
Chronic pain in the general population is highly prevalent
and significantly impacts quality of life [1, 2]. Chronic
pain is a major burden on patients, physicians, and society.
For back pain alone, total health care expenditures in 2004
and 2005 were estimated at 85 to 100 billion dollars,
respectively [3]. Opioids are among the most potent
analgesics available and are the cornerstone of treatment
for moderate to severe pain associated with cancer [4].
Opioids also have a recognized role in chronic noncancer pain
and can decrease pain and improve function in some patients
[5, 6]. Opioid therapy in chronic noncancer pain, however,
remains controversial [7, 8]. Opioids are far from benign
medications, and their long-term use is associated with
significant side effects, including tolerance, hyperalgesia, and
addiction [8-10]. Problematic opioid use, including compulsive
opioid seeking and addiction, arises in some fraction of opioid-treated chronic pain patients. Herein we review the
literature relevant to chronic pain and opioid addiction published over recent years. Moreover, we provide some
discussion on preclinical evidence for possible mechanistic
interactions between pain and addiction.
Overview
Fishbain and colleagues [11] performed a structured
evidence-based review on the development of abuse/
addiction and aberrant drug-related behaviors (ADRBs)
in chronic pain patients (CPPs) with nonmalignant pain on
exposure to chronic opioid analgesic therapy. The objective
of this review was to determine the percentage of
CPPs who develop abuse/addiction and/or ADRBs on
chronic opioid analgesic therapy. Sixty-seven studies were
reviewed in detail and assigned to one of three subgroups
depending on whether they reported 1) percentages of
CPPs developing abuse/addiction, 2) developing ADRBs,
or 3) percentages diagnosed with alcohol/illicit drug use as
determined by urine toxicology. The analysis for each of
the three groups was further analyzed into those patients
who were preselected for no previous history of abuse or
addiction.
For the abuse/addiction grouping, there were 24 studies
(2507 CPPs) with a calculated abuse/addiction rate of
3.27%. Within this grouping for those studies that had
preselected CPPs for no previous or current history of abuse/addiction, the percentage of abuse/addiction was
calculated at 0.19%. For the ADRB grouping, there were
17 studies (2466 CPPs) and a calculated ADRB rate of 11.5%. Within this grouping for preselected CPPs, the
percentage of ADRBs was calculated at 0.59%. In the urine
toxicology grouping, there were five studies (15,442 CPPs),
and 20.4% of the CPPs had no prescribed opioid in urine
and/or a nonprescribed opioid in urine. For five studies
(1965 CPPs), illicit drugs were found in 14.5%. This study
indicates that only a small percentage of patients will
develop abuse/addiction, and that this percentage can be
substantially less if patients are preselected for no previous
history of abuse or addiction. Although addiction is a real and
potential risk of opioid therapy, these data suggest that only
0.19% of patients with no prior history of abuse or addiction
will actually become addicted. The far greater risk of
addiction, roughly 17 times greater, lies in those patients with
a prior history of abuse and addiction. It seems prudent,
therefore, to carefully screen patients prior to initiating opioid
therapy. A thorough screening algorithm is tantamount to
managing risk. Nonetheless, more epidemiological studies are
required to assess the long-term adverse consequence of
opioid therapy, including opioid addiction.
Clinical Factors Associated with Prescription Opioid
Abuse
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