Using biological samples in epidemiological research on drugs of abuse

Abstract

Blood, oral fluid (saliva), urine and hair are the most commonly used biological matrices for drug testing in epidemiological drug research. Other biological matrices may also be used for selected purposes. Blood reflects recent drug intake and may be used to assess impairment. Oral fluid reflects drug presence in blood and thereby also recent intake, but drug concentrations in this matrix cannot be used to accurately estimate concentrations in blood. Urine reflects drug use during the last few days and in some cases for a longer period, but does not indicate the dose size or frequency of use. Hair reflects drug use during several months, but is a poor matrix for detecting use of cannabis. If using a single drug dose, this can be detected in blood and urine if the sample is taken within the detection timeframes, in most cases also in oral fluid. Single drug use is most often insufficient for producing a positive test result in a sample of hair. For cocaine and amphetamine, weekly use may be needed, while for cannabis a positive result is not guaranteed even after daily use. Refusal rates are lowest for oral fluid and highest for blood and hair samples. The analytical costs are lowest for urine and highest for hair. Combined use of questionnaires/interviews and drug testing detects more drug use than when using only one of those methods and is therefore expected to give more accurate data.

Detection of illicit drugs in oral fluid from drivers as biomarker for drugs in blood

“…Thus, analysis of drugs in oral fluid is a suitable technique when the aim is to detect any recent drug intake, regardless the actual drug concentration in blood. Oral fluid testing is therefore suitable for epidemiological studies of drug use because the refusal rate is lower when collecting oral fluid than when collecting samples of other biological matrices [29][30][31]. In those types of studies, the aim is often to determine aggregated drug use data for the cohort, not accurate estimation of the drug concentration in blood for each individual.…”

Challenges and common weaknesses in case-control studies on drug use and road traffic injury based on drug testing of biological samples

“…Therefore, blood samples should ideally be analysed both for cases and controls. It has earlier been assumed that the presence of a drug in a sample of oral fluid reflects presence in blood (31)(32)(33); therefore, oral fluid was collected instead of blood samples in many studies. However, there are large inter-and intra-individual variations in the drug concentration ratio between oral fluid and blood (34,35).…”

Adapting the ASSIST model of informal peer-led intervention delivery to the Talk to FRANK drug prevention programme in UK secondary schools (ASSIST + FRANK): intervention development, refinement and a pilot cluster randomised controlled trial

“…Unfortunately, objective measures of cannabis use have a poor sensitivity in population surveys, even for heavy daily users, over periods of > 3 months. 60,61 This would preclude identification of a significant proportion of lifetime cannabis use in our study as around 40% had not used cannabis in the past 12 months. This is in addition to other problems of using biomarkers of lifetime drug use, including there being no test currently available for all controlled substances if taken > 3 months ago and there being no test at all for novel psychoactive substances.…”