History, examination and investigation

Dependent users will most likely require medical interventions. In Lothian, drug dependence is defined by the ICD-11 classification of mental and behavioural disorders (WHO, 2018). The following characteristics are indicative of a diagnosis of drug dependence:

• A strong desire or sense of compulsion to take the substance
• Loss of control of substance-taking behaviour
• A characteristic withdrawal syndrome for the substance; or use of the same (or closely related) substance with the intention of relieving or avoiding withdrawal symptoms
• Evidence of tolerance, such that increased doses of the substance are required to achieve the effects originally produced by lower doses
• Salience over alternative pleasures or interests
• Persisting drug use despite harmful consequences

During patient clerking, the following information should be documented:

• Drugs used, including illicit drug use (including frequency and quantity used) and any prescribed medications
• Establish whether the patient is enrolled in a substance misuse program and ask whether the administration of opiate substitution therapy (methadone or buprenorphine) is supervised by a community pharmacist
• Route of drug use e.g. IV, smoked, ingested
• Whether usage is increasing/decreasing
• Recent use, most recent drug taken, and when last taken
• Previous use
• Previous or current treatment: Check TRAK for open care episodes; if the patient has come from prison, check treatment with the prison health centre for an accurate list. Other patients may receive treatment from their GP (check ECS)
• Immunisation status: PWIDs are at greater risk of tetanus and diphtheria. Booster doses should be given if there is any doubt about their immunisation status. If the patient’s vaccination status is unknown and they do not recall (and have no documentation) of receiving a dose of Td/IPV in the last 12 months, a booster dose of Revaxis may be given
• Current or previous engagement with substance use services

When documenting the information above, terms such as IVDU should be avoided to reduce stigmatisation of patients. The terms PWUD/PWID (People Who Use Drugs / People Who Inject Drugs) should be used.

• Injection sites (frequent injectors will have multiple sites of different age and usage)
• Evidence of withdrawal using the Clinical Opiate Withdrawal Scale (COWS). See Opioid dependence suspected or declared by patient.

Drug toxicology (urine or oral)

The results of this may not be available for >24 hours and will not affect acute management of the patient. Positive urinalysis or oral swab testing indicates a drug has been taken but does not indicate when.

ECG

Most patients will have a routine ECG, however this should be completed for all patients prescribed methadone to assess for a prolonged QT interval. (The QT interval is corrected for heart rate by QTc, in men the upper limit of normal is 440ms and in women 460ms)

Prolongation of the QT interval is associated with ventricular arrhythmias and death. Causes other than methadone should be considered and excluded e.g. genetic, adverse drug effects (anti-psychotics), other drug use e.g. cocaine, endocrine and metabolic disturbances. For more information, please refer to the National Clinical Guidelines (Orange Book) (DOH, 2017).

Blood borne viruses

Particularly Hepatitis B, Hepatitis C and HIV.