Prevalence Among the Physically Ill
Defining Abuse and Addiction in the Physically Ill
Physical Dependence
Tolerance
Deficiencies in the Current Nomenclature
Substance abuse appears to be very uncommon among cancer patients. The
reported prevalence of substance abuse issues in cancer patients is much lower than
the prevalence in society at large, general medical populations, and emergency medical departments.[1-5] This relatively low prevalence was also
reported in a Psychiatric Collaborative Oncology Group study, which assessed
psychiatric diagnoses in ambulatory cancer patients from several tertiary care
hospitals.[5] On the basis of structured clinical interviews, fewer than 5% of 215
cancer patients met the Diagnostic and Statistical Manual for Mental Disorders,
3rd Edition (DSM-III) criteria for a substance use disorder.[6]
The relatively low prevalence of substance abuse among cancer patients treated
in tertiary care hospitals may reflect institutional biases or a tendency for
patient underreporting in these settings. Drug abusers who are poor or feel
alienated from the health care system may not seek care in tertiary centers.
Those who are treated in these centers may not acknowledge a history of drug
abuse. The low prevalence of drug abuse in cancer centers, therefore, may not
represent the true prevalence among the cancer population overall.
A survey of patients who were admitted to a palliative care unit found
indications of alcohol abuse in more than 25% of these patients;[7] this, however,
represents highly selected palliative care patients referred to a specialized
inpatient unit.
Defining Abuse and Addiction in the Physically Ill
Epidemiologic studies and clinical management depend on an accepted, valid
nomenclature for substance abuse and addiction. The pharmacologic phenomena of
tolerance and physical dependence are commonly confused with abuse and
addiction. Terminology is also strongly influenced by sociocultural
considerations that may lead to the sending of mixed messages in the clinical setting. The
definitions of addiction and abuse that are applied to patients who are
physically ill have been developed from populations of addicts who do not have
physical illnesses. The clarification of this terminology is an essential step
in improving the diagnosis and management of substance abuse in the palliative
care setting. The list below gives the proposed definitions for these terms.
Proposed Terminology for Substance Abuse
-
Physical dependence: Pharmacologic property of some drugs defined
solely by the occurrence of abstinence syndrome
following abrupt dose reduction, discontinuation
of dosing, or administration of a pharmacologic
antagonist.
-
Tolerance: Diminishing of one or more of the drug effects
(either favorable or adverse) that are caused by
exposure to the drug; may be pharmacologic or
the result of associative learning.
-
Substance abuse: Use of a substance in a manner outside
sociocultural conventions; according to this
definition, all use of illicit drugs and all use
of licit drugs in a manner not dictated by
convention (e.g., according to physician’s
orders) is abuse.
-
Addiction: Commonly used term that does not appear in
current psychiatric nosologies but can be taken
to mean the aberrant use of a substance in a
manner characterized by loss of control,
compulsive or escalating use, preoccupation, and
continued use despite harm.
Physical Dependence
Physical dependence is defined solely by the occurrence of a characteristic
withdrawal or abstinence syndrome following discontinuation of dosing, abrupt
dose reduction, or administration of a pharmacologic antagonist.[8-10] Neither
the dose nor duration of administration of opioids required to produce
clinically significant physical dependence in humans is known. Most
practitioners assume that the potential for abstinence syndrome exists after
opioids have been administered repeatedly for only a few days.
Physical dependence is not apparent unless abstinence is induced. In the
clinical setting, physical dependence on an opioid is not considered a problem
as long as patients are told to avoid abrupt discontinuation of therapy and to
avoid the inadvertent administration of an opioid antagonist (including an
analgesic from the agonist-antagonist class).
There is often confusion among clinicians about the differences between physical
dependence and addiction. Physical dependence, like tolerance, has been
suggested to be a component of addiction,[11,12] and the avoidance of
withdrawal has been postulated to create behavioral contingencies that
reinforce drug-seeking behavior.[13] These speculations, however, are not
supported by experience with opioid therapy for chronic pain. Physical
dependence does not preclude the uncomplicated discontinuation of opioids
during multidisciplinary pain management of nonmalignant pain.[14] Opioid
therapy is routinely stopped without difficulty in cancer patients whose pain
disappears following effective antineoplastic therapy. Indirect evidence for a
fundamental distinction between physical dependence and addiction is provided
by animal models of opioid self-administration, which have demonstrated that
persistent drug-taking behavior can be maintained in the absence of physical
dependence.[15]
Tolerance
Tolerance, a pharmacologic property defined by the need for increasing doses to
maintain effects,[8,9] has been a particular concern with opioid therapy.
Clinicians and patients commonly express concern that tolerance to the
analgesic effects of opioids may compromise the benefits of therapy and lead to a
requirement for progressively higher and ultimately unsustainable doses. It
has been speculated that the development of tolerance to the reinforcing
effects of opioids and the consequent need to increase doses to regain these
effects is an important element in the pathogenesis of addiction.[13]
Despite these concerns, extensive clinical experience with opioid drugs given
for medical reasons has not confirmed that tolerance causes substantial
problems.[16,17] Numerous surveys have demonstrated that most patients can
attain stable opioid doses with a favorable balance between analgesia and side
effects for prolonged periods.
Clinical observation does not support the conclusion that analgesic tolerance
is a substantial contributor to the development of addiction. It is widely
accepted that addicts who do not have a medical disorder may not have
any of the manifestations of analgesic tolerance. Opioid-treated patients who
present with analgesic tolerance typically do so without evidence of abuse or
addiction.
Deficiencies in the Current Nomenclature
The definitions of tolerance and physical dependence highlight deficiencies
in the current nomenclature applied to substance abuse. The terms addiction
and addict are particularly troublesome. In common parlance, these labels
are often inappropriately applied to describe both aberrant drug use
(reminiscent of the behaviors that characterize active abusers of illicit
drugs) and phenomena related to tolerance or physical dependence. Clinicians
and patients may use the word addicted to describe compulsive drug-taking in
one patient and to describe nothing more than the possibility for withdrawal
symptoms in another. It is not surprising that patients, families, and staff
become very concerned about the outcome of opioid treatment when this term is
applied.
The labels addict and addiction should never be used to describe patients
who are only perceived to have the capacity for abstinence syndrome. These
patients must be labeled physically dependent. Use of the word dependent
alone also should be discouraged because it fosters confusion between physical
dependence and psychological dependence, a component of addiction. For the
same reason, the term habituation should not be used.
The psychiatric terminology applied to drug abuse and addiction, which has been
codified in the DSM-IV, is also problematic.[12] The DSM-IV eschews the term
addiction altogether and offers definitions of two types of substance use
disorders: substance abuse and the more serious substance dependence. The
criteria for substance abuse are focused on the negative psychosocial sequelae
of drug use rather than the pattern of use. In contrast, a pattern of use
outside of sociocultural convention is considered to be the most important
criterion for abuse in other definitions (see list on Proposed Terminology for Substance Abuse).[18,19] The disparity
in these definitions of abuse is confusing and underscores the challenge in
labeling drug-taking behaviors in patients who are receiving potentially
abusable drugs for legitimate medical purposes.
The DSM-IV criteria for substance dependence highlight psychosocial dysfunction
and add the dimensions of physical dependence and tolerance. This is perhaps
the most striking example of the nomenclatural problems that occur when
criteria developed in substance abusers without medical illnesses are applied
in a different context.[20] Most of the criteria for substance dependence
disorder indicate that the term is meant to be used in a manner synonymous with
addiction. The criteria of tolerance and physical dependence, therefore, are
inappropriate and preclude the use of this terminology in the medically ill who
may develop tolerance and physical dependence as expected consequences of
therapeutic drug use.
References
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Colliver JD, Kopstein AN: Trends in cocaine abuse reflected in emergency room episodes reported to DAWN. Drug Abuse Warning Network. Public Health Rep 106 (1): 59-68, 1991 Jan-Feb.
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Gfroerer J, Brodsky M: The incidence of illicit drug use in the United States, 1962-1989. Br J Addict 87 (9): 1345-51, 1992.
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Regier DA, Myers JK, Kramer M, et al.: The NIMH Epidemiologic Catchment Area program. Historical context, major objectives, and study population characteristics. Arch Gen Psychiatry 41 (10): 934-41, 1984.
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Burton RW, Lyons JS, Devens M, et al.: Psychiatric consultations for psychoactive substance disorders in the general hospital. Gen Hosp Psychiatry 13 (2): 83-7, 1991.
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Derogatis LR, Morrow GR, Fetting J, et al.: The prevalence of psychiatric disorders among cancer patients. JAMA 249 (6): 751-7, 1983.
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Bruera E, Moyano J, Seifert L, et al.: The frequency of alcoholism among patients with pain due to terminal cancer. J Pain Symptom Manage 10 (8): 599-603, 1995.
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Portenoy RK: Opioid tolerance and responsiveness: research findings and clinical observations. In: Proceedings of the 7th World Congress on Pain, 1994. 595-619.
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Foley KM: Clinical tolerance to opioids. In: Basbaum AI, Besson JM, eds.: Towards a New Pharmacotherapy of Pain. Chichester, NY, John Wiley and Sons, 1991, pp 181-203.
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American Psychiatric Association.: Diagnostic and Statistical Manual of Mental Disorders: DSM-IV. 4th ed. Washington, DC: American Psychiatric Association, 1994.
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Halpern LM, Robinson J: Prescribing practices for pain in drug dependence: a lesson in ignorance. Adv Alcohol Subst Abuse 5 (1-2): 135-62, 1985 Fall-1986 Winter.
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Dai S, Corrigall WA, Coen KM, et al.: Heroin self-administration by rats: influence of dose and physical dependence. Pharmacol Biochem Behav 32 (4): 1009-15, 1989.
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Jaffe JH: Current concepts of addiction. In: O'Brien CP, Jaffe JH, eds.: Addictive States: Research Publications-Association for Research in Nervous and Mental Disease. Vol. 70. New York, NY: Raven Press, 1992, pp 1-21.
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