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Prescribing drugs of dependence in general practice

Part A - Clinical Governance Framework

Appendix G. Assessment of current drug and alcohol use

Last revised: 01 Nov 2019

Assessing drug and alcohol use by patients

History

History taking should include:

  • types of drugs used
  • quantity, frequency and pattern of use
  • route of administration
  • symptoms of dependence
  • source of drug (including preparation)
  • prescribed medication • tobacco use
  • alcohol use, including quantity, frequency and pattern of use.82

Drug testing

There are a range of drug tests, including:82

  • Screening tests – These are usually carried out first. They are quick, cheap and easy. They are usually done using immunoassay and can be performed in the laboratory or using point-of-care or dipstick tests. Negative results can be reliably accepted. Positive results usually need a confirmatory test.
  • Confirmatory tests – These tend to use gas or liquid chromatography and mass spectrometry. They are slower and more expensive, but can detect drugs and their metabolites. These are the gold standard for drug testing.
  • Urine testing – This is usually performed. It can show drug use over recent days and is a non-invasive test. Urine specimens may be adulterated (eg addition of chemicals, dilution by drinking large volumes of fluid), substituted or be prone to pre-collection abstinence of drugs that may produce a misleading result. It is only very occasionally necessary to directly observe a urine specimen being given, and the patient’s informed consent is needed for this.
  • Oral fluid testing – Oral fluid is easier to collect, but drugs are present in lower concentrations and only very recent drug use over the last 24–48 hours can be detected. However, it is less easy to adulterate.
  • Hair testing – These tests can show drug use over the past few months. It is poor at detecting very recent use. However, it does not differentiate between continual and sporadic use. It is also more complicated and is only performed in some laboratories.

Written procedures should be in place for the collection and storage of biological samples, their dispatch to a laboratory and the discussion and management of reported results.

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