Harmful pattern of use of cannabis

Essential (Required) Features:

• A pattern of continuous, recurrent, or sporadic use of cannabis that has caused clinically significant damage to a person’s physical health or mental health (e.g., Cannabis-Induced Mood Disorder), or has resulted in behaviour leading to harm to the health of others.
• Harm to health of the individual occurs due to one or more of the following: (1) behaviour related to intoxication; (2) direct or secondary toxic effects on body organs and systems; or (3) a harmful route of administration.
• Harm to health of others includes any form of physical harm, including trauma, or mental disorder that is directly attributable to behaviour related to substance intoxication on the part of the person to whom the diagnosis of Harmful Pattern of Use of Cannabis applies.
• The pattern of cannabis use is evident over a period of at least 12 months if cannabis use is episodic or at least 1 month if use is continuous.
• Harm to health is not better accounted for by another medical condition or another mental disorder, including another Disorder Due to Substance Use (e.g., Substance Withdrawal).

Note: Harm to the health of the person to whom the diagnosis applies includes injuries caused by behaviour related to intoxication (e.g., impulsive aggressive behaviour, psychomotor impairment leading to injury; acute health problems resulting from substance use (e.g., overdose, acute gastritis, the effects of hypoxia or prolonged hyperactivity or inactivity), and exacerbation or decompensation of pre-existing chronic health problems (e.g., hypertension, liver disease, or peptic ulceration). Harm may also result from a harmful route of administration (e.g., injecting drug use causing blood-borne virus infections, cocaine use causing a perforated nasal septum). The relevant diagnostic codes from other chapters of the ICD-11, including the chapter on Injury, Poisoning or Certain Other Consequences of External Causes, should be used to describe the specific health consequences of the harmful substance use.

Harm to the health of others includes any form of physical harm, including trauma (e.g., impaired driving causing a motor vehicle accident, assaultive behaviour leading to bodily harm to another person) or mental disorder (e.g., Post-Traumatic Stress Disorder arising from an assault by the intoxicated individual) that is directly attributable to behaviour due to substance intoxication on the part of the person to whom the diagnosis of Harmful Pattern of Psychoactive Substance Use applies.

Course Specifiers:

A specifier is used to further describe the harmful pattern of substance use, using a fifth-digit code. The fourth-digit code indicates the substance class (i.e., 1 for cannabis).

6C41.10 Harmful Pattern of Use of Cannabis, episodic

This category is assigned when all the diagnostic requirements for Harmful Pattern of Use of Cannabis are met and there is evidence of a pattern of recurrent episodic or intermittent use of cannabis over a period of at least 12 months that has caused clinically significant harm to a person’s physical or mental health or has resulted in behaviour leading to harm to the health of others.

6C41.11 Harmful Pattern of Use of Cannabis, continuous

This category is assigned when all the diagnostic requirements for Harmful Pattern of Use of Cannabis are met and there is evidence of a pattern of continuous cannabis use (daily or almost daily) over a period of at least 1 month that has caused clinically significant harm to a person’s physical or mental health or has resulted in behaviour leading to harm to the health of others.

6C41.1Z Harmful Pattern of Use of Cannabis, unspecified

Additional Clinical Features:

• There must be explicit evidence of harm to the individual’s physical or mental health, or of related behaviour due to Cannabis Intoxication that has led to harm to the physical or mental health of others. There must also be a clear causal relationship between the harm to health and the episodic or continuous use of cannabis.
• The likelihood of harm to self or others due behaviour related to intoxication varies substantially by substance. For example, such behaviour is unlikely to arise from caffeine or nicotine intoxication.
• As more information becomes available about symptoms and behaviours related to the pattern of cannabis use as well as physiological features indicative of neuroadaptation to the substance, the diagnosis may be changed to Cannabis Dependence if diagnostic requirements are met.

Boundary with Normality (Threshold):

• The diagnosis of Harmful Pattern of Use of Cannabis requires clinically significant harm to the individual’s physical or mental health or that of others. Examples of impact on physical or mental health that would not be considered clinically significant include mild hangovers, brief episodes of vomiting, or transient depressed mood.
• A pattern of cannabis use may cause a range of problems in functioning (e.g., missed appointments, arguments with loved ones) that are not sufficiently severe to constitute clinically significant harm to physical or mental health. Such problems are not a sufficient basis for a diagnosis of Harmful Pattern of Use of Cannabis.

Developmental Presentations:

• Harmful Pattern of Use of Cannabis is often a characteristic of late adolescence and young adulthood, and injuries and the consequences of aggressive behaviour are particularly common in this age group.
• Harmful Pattern of Use of Cannabis in older adults may cause injuries and fractures due to the combination of lowered tolerance, psychomotor impairment induced by a substance, and disorders associated with ageing such as osteoporosis and Dementia.

Sex- and/or Gender-Related Features:

• The prevalence of Harmful Pattern of Use of Cannabis is higher in males than females, but the gender differential is smaller in countries where women play a greater role in the workforce. Gender differences in injuries and other forms of harm due to substance use are recognized.

Boundaries with Other Disorders and Conditions (Differential Diagnosis):

• Boundary with Hazardous Use of Cannabis: Hazardous Use of Cannabis is classified in the chapter on ‘Factors Influencing Health Status or Contact with Health Services’ in the ICD-11 and not in the chapter on Mental, Behavioural, and Neurodevelopmental Disorders. Hazardous Use of Cannabis appreciably increases the risk of harmful physical or mental health consequences to the user or to others to an extent that warrants attention and advice from health professionals, but has not resulted in specific identifiable harm and therefore does not meet the diagnostic requirements for Harmful Pattern of Use of Cannabis.
• Boundary with Episode of Harmful Use of Cannabis: If the harm to health is a result of a single episode of use rather than a pattern of substance use, whether episodic or continuous, a diagnosis of Episode of Harmful Use of Cannabis should be assigned. Cannabis use is generally considered to be following a pattern if there has been at least episodic or intermittent use over a period of at least 12 months. If harm is caused by use of cannabis but no information is available about the pattern or history of cannabis use, a diagnosis of Episode of Harmful Use of Cannabis may be assigned until such time as evidence for a pattern of use is ascertained.
• Boundary with Cannabis Dependence: In Cannabis Dependence, individuals use cannabis persistently despite harm and adverse consequences. Harm caused by such use may be similar to that observed in Harmful Pattern of Use of Cannabis. However, Cannabis Dependence also includes additional features of impaired ability to control use and increasing priority given to the substance use over other activities. Physiological features (e.g., tolerance) may also be present. If all diagnostic requirements for Cannabis Dependence are met, Harmful Pattern of Use of Cannabis should not be assigned.
• Boundary with Cannabis Intoxication: Cannabis Intoxication is defined by cannabis use that results in clinically significantly, transient cannabis-specific symptoms. Recovery from Cannabis Intoxication is generally complete and absent of physical or mental sequelae. A pattern or repeated intoxication may or may not result in harm to a person’s physical or mental health or to the health of others. If there is continuing damage or harm as a result of repeated or continuous use of cannabis, a diagnosis of Harmful Pattern of Use of Cannabis may be assigned. If relevant at the time of the clinical encounter (e.g., in an emergency room), Harmful Pattern of Use of Cannabis may be diagnosed with an associated diagnosis of Cannabis Intoxication.
• Boundary with Cannabis Withdrawal: Cannabis Withdrawal occurs upon cessation or reduction of a substance in the context of physiological dependence or when cannabis has been taken for a prolonged period or in large amounts. Some features of cannabis withdrawal may include physical or mental harm (e.g., headache, insomnia, anxiety, depressed or dysphoric mood). If the symptoms are entirely explained by the Cannabis Withdrawal, an additional diagnosis of Harmful Pattern of Use of Cannabis is not warranted. However, if the symptoms substantially exceed the expected withdrawal syndrome in duration or type or severity and the diagnostic requirements for Cannabis Dependence are not met, Harmful Pattern of Use of Cannabis can be assigned as the primary diagnosis, with an associated diagnosis of Cannabis Withdrawal.
• Boundary with Cannabis-Induced Mental Disorders: If a Cannabis-Induced Mental Disorder has occurred as a form of harm resulting from a pattern of cannabis use, both Harmful Pattern of Use of Cannabis and the relevant Cannabis-Induced Mental Disorder should be diagnosed (e.g., Harmful Pattern of Cannabis Use with Cannabis-Induced Anxiety Disorder).
• Boundary with other mental disorders and other medical conditions: Numerous mental disorders as well as subthreshold symptoms may co-occur with episodic or continuous patterns of cannabis use. Similarly, continuous or episodic cannabis use increases the risk for mental disorders as well as other medical conditions. Co-occurring mental disorders and comorbid medical conditions should be diagnosed separately, along with a diagnosis of Harmful Pattern of Use of Cannabis.