How to test – what do tests tell

First published: 10 May 2019 | Last updated: 20 May 2019

How to test – What do tests tell?

The provision of a screening service for drugs of abuse has an important role in the diagnosis and management of drug misuse. Screening results can also provide objective information on trends in drug usage within selected populations, which can assist our understanding of the epidemiology of drug abuse and help in the resource management of treatment facilities.

However, the pattern and range of substances abused can change according to the rules of supply and demand, and according to what is available, fashionable or being imported. These issues make the choice of analytical technique applied difficult. For example, prescribed medication and some over-the-counter remedies may produce “false positive” results with immunoassay and point of care screening techniques and these limitations must be clearly recognised to prevent misdiagnosis.

Any service therefore needs to be able to provide rapid interpretive results following an appropriate analytical investigation. But the complexity of the interpretation of analytical results increases with the degree of complexity of the system used to perform the analysis and the matrix chosen and there can be several explanations for the presence of a compound in the specimens analysed. It is for this reason that the interpretation of analytical results needs to be performed by those with a thorough working knowledge of the analytical systems and their limitations.

Declaration of interest and funding: None


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Dr Steve George