Urine or Oral Fluid for Random Testing? A Review of Real World Data

Most comprehensive workplace drug testing programmes include random or unannounced testing as a means to deter staff from drug use and mitigate risk. Testing can be performed on urine or oral fluid (saliva) either by on-site lateral flow tests that give an immediate negative, or a not-negative/unconfirmed result, or by return of the full sample to the laboratory for screening. Any sample, whether screened on site or at the laboratory, is then confirmed using a sensitive and specific method that can prove the identity of the drugs present and also determine the difference between related drugs, such as morphine and codeine. This study reviews data from over 12 months to determine the positive rates for urine and oral fluid (saliva) testing. This allows employers to determine the likely effectiveness of their screening policy and estimate the number of staff expected to produce a not-negative/unconfirmed result. The results show that the primary screening results, whether based on urine or oral fluid, are reliable with a positive predictive value of better than 80% for commonly used drugs. Urine testing identifies 8.9% of samples as requiring further confirmation testing, whereas oral fluid (saliva) identifies 3.4%. Urine testing is better where employers wish to ensure a drug-safe workplace, whereas oral fluid (saliva) testing will probably lead to a lower level of disciplinary action.