Drug Testing Business Success

Oral Fluid vs Urine 2018 – Safety Relevance Score. A discussion.

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Of all the arguments regarding oral fluid vs urine drug testing, relevance to safety must be considered as one of the most important, if not the primary rationale for choosing either method.

We can introduce the term “relevance score” here as a tool to measure relevance of drug testing to safety and potential impairment.

When advising clients on which methodology should be chosen I always stress the importance of logic being applied to each circumstance.  It is certainly not logical to choose urine over oral fluid for example due to assertions it is more accurate, more proven or reliable – that is old school, here comes the new school of thinking.

Two of the key drugs of interest in Australia are Methamphetamine and Marijuana, being the two most prevalent illicit drugs in use.

Method:

Consider the detection windows for each drug in urine and oral fluid.

Consider the likely impairment period based upon known data.

Table 1: What percentage of the urine drug detection timeline (window) is relevant to potential or likely impairment?

Detection windows used below are widely quoted and generally accepted in the Australian marketplace.
Drug Type & Usage Window of Detection – Urine Likely Impairment Period following use Period of detection timeline relevant to impairment & safety
THC – Chronic user 6 weeks (average) 6 hours

OR

1 day (with hangover)

0.6%

 

2.38%

THC – Single use (say one several hour session) 1 week 6 hours

OR

1 day (with hangover)

3.57%

 

14.28%

Methamphetamine

All user types

3 days 24 hours

36 hours (with hangover)

48 hours (with more extreme hangover)

33.33%

50.00%

 

66.66%

Application of this logical test scores urine drug testing and its relevance to impairment and safety less than 100% in all cases and 50% or less in 6 of the 7 scenarios.

The overall average safety relevance score becomes 28.37% for a urine drug test measured against impairment and safety.

Table 2: What percentage of the oral fluid drug detection timeline (window) is relevant to potential or likely impairment?

Detection windows used below are widely quoted and generally accepted in the Australian marketplace.
Drug Type & Usage Window of Detection – Oral Likely Impairment Period Period of detection timeline relevant to impairment & safety
THC – Chronic user 12 hours 6 hours

OR

1 day (with hangover)

100.00%

 

50.00%

THC – Single use 12 hours 6 hours

OR

1 day (with hangover)

100.00%

 

50.00%

Methamphetamine 36 hours
Some studies have shown that methamphetamine can be detected for in excess of 48 hours in oral fluids.
24 hours

36 hours (with hangover)

48 hours (with more extreme hangover)

 

100.00%

100.00%

75.00%Detection window is arguably up to 48 hours with quality equipment so this would then be 100.00%

Note that application of this logical test scores oral fluid drug testing and its relevance to impairment and safety 100% for each drug in most scenarios. The average safety relevance score becomes 82.14% for an oral fluid drug test measured against impairment and safety.

More Conclusions from Table 2 above:

By the above principles of measurement Oral fluid testing of THC is relevant to safety at a relative rate of between 350% and 2100% greater than for urine testing. Oral fluid testing of Methamphetamine is relevant to safety at a rate of 200% greater than urine testing.

Table 3 – Overall Summaries

Drug type & use

 

Urine testing irrelevant Urine testing relevant
THC – Chronic use

 

97.62% of the time 2.38% of the time
THC – Single/brief use

 

85.72% of the time 14.28% of the time
Methamphetamine – Single/brief use

 

50% of the time 50% of the time
Methamphetamine – Chronic use (with hangover period)

 

33% of the time 66% of the time
 

Urine Overall

 

Irrelevant

71.63% of the time

Relevant

28.37% of the time

 

Drug type & use

 

 

Oral testing irrelevant

 

Oral testing relevant

THC – Chronic use (assuming hangover really occurs up to 24 hours)

 

50.00% of the time 50.00% of the time
THC – Single/brief use

 

0.00% of the time 100.00% of the time
Methamphetamine – Single/brief use

 

0.00% of the time 100.00% of the time
Methamphetamine – Chronic use (with 48 hour hangover period)

 

25.00% of the time 75.00% of the time
 

Oral Overall

 

Irrelevant

17.86% of the time

Relevant

82.14% of the time

By reference to Table 1 below, the safety relevance score for urine drug testing is as low as 2.38% and at best 14.28% for THC (cannabis) when it comes to detection of safety risk and potential impairment. For Methamphetamine in urine the safety relevance score is as low as 33.33% and at best 66.6%. Conversely, the oral fluid safety relevance score is typically 100.00% for THC and Methamphetamine. It only falls to 50% in the case of THC if we include the concept of hangover effect prolonging the impairment window. The typical window for THC impairment is 6 hours (oral fluid detects 12 hours) and there is only “weak evidence for hangover effects up to 24 hours after use (Hall et al., 2002).”

More Conclusions from Table 1 above:

Conversely THC may potentially be detected in urine in the hangover phase 100% – 2.38% = 97.62% of the timeline when the chronic user is not impaired. Or in the case of the single use example 100% – 14.28% = 85.72% of the timeline when the single-use user is not impaired.

Conversely METHAMPHETAMINE may potentially be detected in urine 100% – 50.0% = 50.0% of the time when the chronic user is not impaired (assuming a 36 hour impairment period with some hangover effect). This irrelevant period becomes 33.3% of the time only when a 48-hour hangover occurs, assuming this may be sometimes the case.

Conclusion:

Based upon the above information we can demonstrate the huge importance of relevance to safety when choosing a drug testing methodology.

Ask yourself whether it is fair to discipline a worker due to a failed urine test which may be irrelevant to safety 71.63% of the time.  Keep this in mind when developing drug and alcohol policies and procedures for your workplace or for your clients.

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About the Author:

Cameron Stuart provides forward thinking business education services to the Drug Testing Industry through his company Drug Testing Business Success. Key principles of his business include low cost strategies for maximum results.
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