Pain control providers take on substantial risk prescribing narcotics to patients.
Devoting one's life to relieving pain is a humane and noble profession to participate in, however, the incidence of drug diversion among patients is rampant.
A 2005 study by Pembrook in Pain Medicine News displayed that 35% of patients failed to show the expected medication concentration in their urine screens.
So what are the methods pain doctors use to drug screen their patients for compliance?

1. Urine - this is the most common and widespread tool utilized for testing compliance.
   The window of detection ranges from 12 to 72 hours.
   It is also useful for testing drug metabolites.
   Pain doctors can do a screen in the office that will give a positive or negative result for numerous drug classes.
   Then the sample can be screened by gas chromatography for extremely specific confirmation of drug levels.
   
2. Sweat - Perspiration provides a detection window of around a week.
   The collection method is inefficient - patients need to wear a patch for days to weeks.
   It's not a widespread method of screening.
   
3. Hair - The window of detection for hair is lengthy - up to 6 weeks.
   The incidence of false negatives is fairly high and the testing is cumbersome to perform.
   There also is questionable racial bias with individual hair colors binding differentially to certain drugs.
   Like sweat, it is not very efficient for clinical screening.
   
4. Oral saliva - this method of screening offers easy collection with the additional benefit of being able to actually watch the patient produce the sample.
   It has a short detection window (up to 4 hours) and the drugs are generally found at lower levels than what one sees in urine.
   The frequency of positive drug test results in workers has been shown to have similar efficacy with saliva testing in comparison to urine.
   Saliva testing is growing in popularity for drug screening.
   
5. Blood - serum testing is extremely effective in picking up even low levels of drugs.
   The window of detection is very short, just a few hours.
   It is not a very popular method of screening because of the need for blood draws in the office.
   

Monitoring pain medication compliance is an important part of the regimen pain management doctors use to ensure their patients are serious about their treatment and are properly participating in their care.
It's a two way street, and drug screening helps ensure diversion is not occurring.