What's more accurate a urine or saliva drug test?

Posted by Dr Mike Garside on

which is more accurate urine or saliva drug testing UK

How accurate are urine and saliva drug tests when compared to each other

Urine and saliva drug tests are all very accurate, but the results you get when using both side by side can be very different. 

What goes into making a drug test kit accurate

Accuracy is a very important consideration when undertaking a test or screen of any type. This is especially true when performing drug and alcohol testing. The drug test kit you select should be accurate and give a result you can trust.

So how do you ensure the drug test kit has the best accuracy, and how do you define accuracy?

Drug test kits must meet a basic set of standards, to be exported from one country to another. These standards are constantly changing, and incorporating new developments and drug test membranes.

Certifications

Drug testing kit manufacturers must meet certain quality standards which are international and others which are regional. These certifications include: ISO, CE, FDA, TUV certifications.

Some of these will be general quality certification applied to manufacturing and distribution process and not specifically the product you are considering.

With drug test kits the quality certification must meet a higher regulatory quality to ensure In Vitro Medical Device (IVDD) standards which are generally more rigorous than non medical device test kit quality standards. These include individual batch test reports.

Accuracy relates to three characteristics measured on a drug test kit

  • Selectivity,
  • Sensitivity
  • Specificity

Selectivity and specificity are independent, as a drug test must selectively identify a drug compound at a very low level, but not cross react with other compounds at these very low levels, and if it does react to other compounds these should rarely be expected to be present.

Sometimes balancing sensitivity to avoid cross reactivity is also a factor, but if the drug test does not detect low levels of a drug, then the detection window will be shortened or non-existent.

Selectivity, sensitivity and specificity will vary slightly depending on the drug that you are testing for and whether it is a urine or saliva drug test, but for rapid onsite drug test kits the combined accuracy should be around 97-98% when compared to the gold standard of a laboratory GCMS drug test for the same drug on the same sample, whether you choose urine or saliva drug testing kits.

The drug and alcohol testing industry is evolving rapidly

The last decade has seen the explosion of saliva testing, and the expansion of the range of drugs that can be tested for has developed almost as quickly as the development of new recreational drug market. Finger print and sweat or skin drug testing could revolutionise the drug testing industry in the next decade.

Latest drug tests

Very few of these newer drug tests have massive data sets of test reports to support the accuracy reported from manufacturing laboratory test report data. Because it works in a lab, may not mean it's that good in field testing or general use. Good drug test procedural policy can be an important element in obtaining close to the manufactures claimed accuracy levels.

How to choose the most accurate onsite drug test kits

When choosing a urine or saliva drug test kit look for CE ISO and accuracy levels provided by the supplier or manufacturer. Then ensure the drug testing kits have been imported correctly, stored correctly and delivered without damage. Drug tests are prone to thermal exposure damage, both heating >30*C and freezing damage. Either will reduce the life and function of the drug testing kits.


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