Approach
The diagnosis of opioid use disorder is clinical, and therefore a thorough history and psychiatric and medical examination, along with appropriate laboratory tests, are essential for making a diagnosis. After establishing a diagnosis of opioid use disorder, it is important to ascertain whether there are any comorbid substance use disorders or medical and psychiatric problems. A social history should also be taken to assess living situation, employment, and risk of harm (e.g., physical, emotional, or sexual abuse by a family member or intimate partner).[40]
History
Diagnosis of opioid use disorder should be made according to the Diagnostic and statistical manual of mental disorders, 5th edition, text revision (DSM-5-TR).[1]
Two or more of the following manifestations should have occurred within a 12-month period:
Using larger amounts of opioids or over a longer period than was intended
Persistent desire to cut down or unsuccessful efforts to control use
Great deal of time spent obtaining, using, or recovering from use
Craving, or a strong desire or urge to use substance
Failure to fulfil major role obligations at work, school, or home due to recurrent opioid use
Continued use despite recurrent or persistent social or interpersonal problems caused or exacerbated by opioid use
Giving up or reducing social, occupational, or recreational activities due to opioid use
Recurrent opioid use in physically hazardous situations
Continued opioid use despite physical or psychological problems caused or exacerbated by its use
Tolerance (marked increase in amount to achieve intoxication or desired effect; marked decrease in effect with continued use of same amount)
Withdrawal syndrome as manifested by cessation of opioids or use of opioids (or a closely related substance) to relieve or avoid withdrawal symptoms.
Tolerance and withdrawal criteria are not considered to be met for those taking opioids solely under appropriate medical supervision.
Severity of opioid use disorder is categorised as mild (presence of 2-3 symptoms), moderate (4-5 symptoms), or severe (6 or more symptoms).
An individual is in early remission where none of the criteria for opioid use disorder have been met for at least 3 months but for less than 12 months (with the exception of craving, or a strong desire or urge to use opioids), but full criteria for opioid use disorder were previously met. Sustained remission is achieved where none of the criteria for opioid use disorder have been met at any time during a period of 12 months or longer (with the exception of craving, or a strong desire or urge to use opioids), but full criteria for opioid use disorder were previously met.
It is also important to specify whether an individual with opioid use disorder is on maintenance therapy, such as taking a prescribed agonist (methadone), partial agonist (buprenorphine), agonist/antagonist (buprenorphine/naloxone), or a full antagonist (naltrexone).
It should be specified if the individual is in an environment where access to opioids is restricted, i.e., in a controlled environment (e.g., closely supervised and substance-free jails, therapeutic communities, and locked hospital units).
According to the World Health Organization's International statistical classification of diseases and health related problems, 11th revision (ICD-11) classification of mental, behavioural, or neurodevelopmental disorders, diagnosis of conditions due to use of opioids is categorised into three pathological syndromes, each defined by a set of essential features:[2]
Opioid dependence
A pattern of recurrent episodic or continuous use of opioids with evidence of impaired regulation of opioid use that is manifested by two or more of the following:
Impaired control over opioid use (i.e., onset, frequency, intensity, duration, termination, context)
Increasing precedence of opioid use over other aspects of life, including maintenance of health, and daily activities and responsibilities, such that opioid use continues or escalates despite the occurrence of harm or negative consequences (e.g., repeated relationship disruption, occupational or scholastic consequences, negative impact on health)
Physiological features indicative of neuroadaptation to the substance, including:
Tolerance to the effects of opioids or a need to use increasing amounts of opioids to achieve the same effect
Withdrawal symptoms following cessation or reduction in use of opioids, or
Repeated use of opioids or pharmacologically similar substances to prevent or alleviate withdrawal symptoms.
The features of dependence are usually evident over a period of at least 12 months, but the diagnosis may be made if use is continuous (daily or almost daily) for at least 3 months.
Opioid intoxication
Transient and clinically significant disturbances in consciousness, cognition, perception, affect, behaviour, or co-ordination that develop during or shortly after the consumption or administration of opioids.
The symptoms must be compatible with the known pharmacological effects of opioids, and their intensity is closely related to the amount of opioids consumed.
Presenting features may include somnolence, stupor, mood changes (e.g., euphoria followed by apathy and dysphoria), psychomotor retardation, impaired judgement, respiratory depression, slurred speech, and impairment of memory and attention. In severe intoxication, coma may ensue. A characteristic physical sign is pupillary constriction but this sign may be absent when intoxication is due to synthetic opioids.
The symptoms of intoxication are time-limited and abate as opioids are cleared from the body.
Symptoms are not better accounted for by another medical condition or another mental disorder.
Opioid withdrawal
The presence of a clinically significant cluster of symptoms, behaviours, and/or physiological features that occurs upon cessation or reduction in the use of opioids in individuals who have developed dependence on opioids or have used opioids for a prolonged period or in large amounts. Opioid withdrawal can occur when prescribed opioids (e.g., oxycodone, morphine) have been used in standard therapeutic doses.
Presenting features may include depressed or dysphoric mood, craving for an opioid, anxiety, nausea or vomiting, abdominal cramps, muscle aches, yawning, perspiration, hot and cold flashes, hypersomnia (typically in the initial phase) or insomnia, diarrhoea, piloerection, and pupillary dilation.
The severity and time course of withdrawal is influenced by many factors that include the type of opioid taken; its half-life and duration of action; the amount, frequency, and duration of opioid use before cessation or reduction of use; prior experience of opioid withdrawal; and expectations of the severity of the syndrome.
Symptoms are not better accounted for by another medical condition or another mental disorder.
Use of opioids tips into a disorder when the pattern of use causes harm to the person's physical or mental health or has resulted in behaviour leading to the harm of others.[2] Harm to the health of the individual occurs due to behaviour related to intoxication, direct or secondary toxic effects on body organs and systems, or a harmful route of administration.[2] Harm to health of others includes any form of physical harm, including trauma, or a mental disorder attributable to intoxication behaviour.[2] Both DSM-5-TR and ICD-11 classify opioid use disorder when a harmful pattern of use is evident over a 12-month period or at least 1 month if use is continuous.[1][2]
A high level of suspicion must be maintained for concurrent use of other drugs (marijuana, benzodiazepines, and cocaine are the most common in opioid abusers), as well as any comorbid psychiatric illnesses, such as bipolar disorder, ADHD, major depression, anxiety disorders, and personality disorders.[17][18][19][20] Clinical confirmation of these diagnoses should be made by a psychiatrist in the absence of positive substance abuse on toxicology screen.
Clinical presentation
Patients with opioid use disorder may present with chronic constipation, weight loss, or symptoms of either tolerance or withdrawal. Tolerance may manifest as either blunting to the pleasurable effects of opioids, or adverse effects such as nausea and sedation. These can be seen as early as 2 to 3 days following continuous use of opioids, and the individual may seek to increase consumption of the drug to obtain similar drug-reinforcing effects.
Symptoms of withdrawal can occur within the same day or up to 72 hours after the last dose of opioid, depending on the half-life of the drug concerned. For example, heroin has a short half-life and is associated with withdrawal onset within 12 hours of last use, whereas withdrawal symptoms with methadone may manifest 24 to 74 hours after last use.[41] Initial manifestations include sneezing, yawning, and restless sleep. More severe manifestations include nausea, vomiting, abdominal cramps, diarrhoea, backache, muscle spasm, hot and cold flashes, and insomnia. The duration of withdrawal symptoms is also correlated with the half-life of the opioid, with heroin withdrawal lasting 4 to 5 days, compared with 7 to 14 days or sometimes longer for methadone.[41]
Physical examination
The physician should look for specific signs of opioid use. Signs will depend on whether the patient is acutely intoxicated, has a more chronic problem, has overdosed, or is going through withdrawal.
Opioid intoxication: somnolence, stupor, mood changes (e.g., euphoria followed by apathy and dysphoria), psychomotor retardation, impaired judgement, respiratory depression, slurred speech, and impairment of memory and attention.[2] Miosis may be absent if intoxication is due to synthetic opioids such as fentanyl.[2] In severe intoxication, coma may ensue.[2]
Opioid use disorder: miosis, sedation, or evidence of needle marks, scars, or skin necrosis at injection sites.
Opioid overdose: unconsciousness, pinpoint pupils, apnoea (<10 breaths per minute), or very slow pulse rate (<40 beats per minute).
Opioid withdrawal: depressed or dysphoric mood, craving for an opioid, anxiety, nausea or vomiting, abdominal cramps, muscle aches, yawning, perspiration, hot and cold flashes, hypersomnia (typically in the initial phase) or insomnia, diarrhoea, piloerection, and dilated pupils.[2] Neonates of opioid-dependent mothers often present with seizures during withdrawal.
Addiction Severity Index
The Addiction Severity Index (ASI) is a widely known structured interview designed to assess the patient's problem severity in seven areas of functioning: medical status, employment/support status, drug use, alcohol use, legal status, family/social relationships, and psychiatric status. Addiction Severity Index Opens in new window
Composite scores ranging from 0 (minimum severity) to 1 (maximum severity) are provided in each area to reflect problem severity in the last 30 days. These are based on subsets of items that have been found to be consistently associated with treatment outcome. A higher score on the ASI indicates a greater need for treatment.
The ASI is the most widely used clinical instrument in addiction treatment programmes in the US, and is used for treatment planning and follow-up.[42] A brief version of the ASI (ASI-Lite) and a computerised version are also available.
Urine and saliva drug tests
A urine or saliva drug screen should be ordered initially if there is a clinical suspicion of drug use.
The Drug Screen 9 (DS-9) is one of the more common immunoassays, and tests a urine sample for opioids (oxycodone, hydrocodone, hydromorphone, morphine, and codeine only), cocaine, marijuana, benzodiazepines, phencyclidine, amfetamines, and barbiturates. The test will report 'positive' for opioids in opioid abusers; however, it will not specifically identify which opioid has been taken.
Point of care tests (POCTs) may be appropriate in some circumstances (e.g., in primary care) as the initial screening test. They are conducted on a specimen of urine or saliva collected in a setting such as a practitioner’s office. POCTs use well-established immunoassay technologies for drug detection. The principal advantage of POCTs over laboratory screening tests, such as DS-9, is that the results are available in approximately 10 minutes. This fast turnaround allows practitioners to discuss the results with the patient during that office visit, and make clinical decisions and act appropriately that day. POCTs are also inexpensive and relatively easy to use with minimal training. Despite these benefits, laboratory testing is more accurate overall, and provides quantitative estimates of drugs and their metabolites.[43]
A positive screen should be followed by a confirmatory urine test due to opioid sensitivity limitations (routine immunoassays do not usually detect synthetic or semisynthetic opiates [e.g., fentanyl, methadone, propoxyphene, meperidine, tramadol, pentazocine]). Certain medications (e.g., antibiotics) can also interfere with the screening test and produce false-positive results. The opioid confirmation urine test by gas chromatography-mass spectrometry is the most specific and sensitive test for identifying opioids.[43] This test will identify the specific opioid in the urine.
The detection times for opioids in the urine are 48 to 72 hours for most opioids, with the exception of methadone, which may be detected up to 7 days after use.[44][45] A positive opioid confirmation test should lead to a comprehensive evaluation for opioid use disorder if there are no legitimate prescriptions of opioids.
With technological advances, drugs of abuse, including opioids, can also be detected in other body fluids, such as sweat, and in hair. Despite this, urine and saliva drug tests remain the most validated and clinically acceptable tests to date.
Other laboratory tests
Other tests that should be ordered initially include serum electrolytes, full blood count, urea/creatinine, and liver function tests (LFTs). Due to the risk of associated malnutrition, it is helpful to assess haematological function and electrolytes. LFTs and renal function are important for assessing whether medication dosing adjustments are required. The American Society of Addiction Medicine recommends testing for tuberculosis, hepatitis, and HIV in all patients.[46]
Invesigations for other sexually transmitted infections should be considered: for example, rapid plasma reagin for syphilis.[46] All women of childbearing potential should be tested for pregnancy.[46] Blood cultures are indicated if there are signs or symptoms suggestive of septicaemia (e.g., high fever, altered mental state, and vital sign changes) or infective endocarditis (e.g., fever with heart murmur).
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