Comparing presumptive with direct-to-definitive drug testing in oral fluid vs. urine for a U.S. national sample of individuals misusing drugs

BACKGROUND

The aims are to compare the results of presumptive drug testing with confirmation of positives vs. direct-to-definitive drug testing, combined with investigation of urine vs. oral fluid as test matrices.

METHODS

Paired oral fluid and urine specimens were collected voluntarily and anonymously from 1098 individuals applying for methadone treatment in 11 clinics across 7 U.S. states. All specimens were analyzed by immunoassay (IA) and liquid chromatography-tandem mass spectrometry (LC-MS-MS).

RESULTS

Confirmed IA prevalences for urine were significantly higher than for oral fluid for 7 out of 10 drug classes - benzodiazepines, cannabis, cocaine, methadone, opiates, oxycodone and tramadol. Drug prevalences by direct-to-definitive LC-MS-MS were either the same or higher than prevalences by confirmed IA. Drug prevalences by LC-MS-MS were higher in urine for two drug classes (cocaine, methadone) and higher in oral fluid for two drug classes (buprenorphine, tramadol), but were equivalent in urine and oral fluid when averaged over all 10 drug classes. Certain drugs of special concern such as heroin and buprenorphine were more frequently detected in oral fluid than urine.

CONCLUSIONS

Urine analysis showed some technical advantage over oral fluid in sensitivity to several drug classes within a confirmed IA testing protocol, but this may be outweighed if there is reason to believe that tampering with urine specimens is a significant problem. Overall drug detection by direct-to-definitive testing was similar for oral fluid and urine, but one matrix may be preferable if there is a particular drug of clinical or epidemiological interest.

Comparison of timeline follow-back self-report and oral fluid testing to detect substance use in adult primary care patients

BACKGROUND

Timeline Follow-back (TLFB) interviews using self-report are often used to assess substance use. Oral fluid testing (OFT) offers an objective measure of substance use. There are limited data on the agreement between TLFB and OFT.

METHODS

In this secondary analysis from a multisite study in five primary care sites, self-reported TLFB and OFT data collected under confidential conditions were compared to assess concordance (N=1799). OFT samples were analyzed for marijuana, heroin, cocaine, and non-medical use of prescription opioids. Demographic differences in discordance relative to TLFB and OFT concordant results for marijuana, the only substance with an adequate sample size in this analysis, were examined using multinomial logistic regression.

RESULTS

Overall concordance rates between TLFB and OFT were 94.9 % or higher for each substance, driven by large subgroups with no use. Among participants with discordant use, marijuana was the only substance with lower detection on OFT than self-report (27.6 % OFT-positive only vs 32.2 % TLFB-positive only), whereas cocaine (65.6 % vs 8.6 %), prescription opioids (90.4 % vs 6.0 %), and heroin (40.7 % vs 26.0 %) all had higher detection via OFT than TLFB. Participants who reported marijuana use but had a negative OFT were more likely to be younger, Hispanic, and White compared to those with TLFB and OFT concordant positive results.

CONCLUSIONS

TLFB and OFT show disparate detection of different substances. Researchers should consider the implications of using either self-report or oral fluid testing in isolation, depending on the substance and collection setting. Triangulating multiple sources of information may improve detection of drug use.