A comparative study of screening instruments and biomarkers for the detection of cannabis use

ABSTRACT

Background: The aim of this study was to compare the usefulness of 3 different screening instruments (questionnaires) for the detection of cannabis use (CU) with biological markers in blood and hair. Methods: Ninety-four students were recruited in October 2013. Participants filled out the Severity of Dependence Scale (SDS), the CAGE-AID (“Cut down Annoyed Guilty Eye-opener”—Adapted to Include Drugs), and ProbCannabis-DT questionnaires concerning their possible CU. Blood and hair samples were taken and analyzed by gas chromatography–mass spectrometry. Logistic regression (Nagelkerke R²) and receiver operating characteristic (ROC) curve analyses were performed. THCCOOH (Δ⁹-tetrahydrocannabinoic acid) plasma of ≥5 ng/mL and THC (Δ⁹-tetrahydrocannabinol) hair concentrations of ≥0.1 and ≥0.02 ng/mg were used as the gold standard for CU. The questionnaire results were compared with different concentration ranges for THCCOOH in plasma (<5, 5–75, and >75 ng/mL, indicating the intensity of use) and THC in hair (≥0.02 ng/mg, ≥0.1 ng/mg). Results: The Nagelkerke R² for comparing the SDS, CAGE-AID, and ProbCannabis-DT with THCCOOH in plasma was 0.350, 0.489, and 0.335, respectively. The area under the ROC curve (95% confidence interval) was 0.772 (0.662–0.882), 0.797 (0.710–0.884), and 0.769 (0.669–0.870), respectively. Corresponding sensitivity/specificity were 70%/84%, 100%/59%, and 87%/67%, respectively. These values were similar to those compared to a 0.02 ng/mg THC cutoff in hair. Conclusions: Moderate agreement was found between all questionnaires and biomarkers of CU. The CAGE-AID and probCannabis-DT questionnaires were very sensitive, but less specific. SDS was less sensitive, but more specific.

KEYWORDS:

• CAGE-AID
• cannabis use
• ProbCannabis-DT questionnaire
• SDS
• sensitivity
• specificity

Acknowledgments

We thank Ms. Miriam de Vreugd of the Public Health Department, who organized the recruitment of the students, Mr. Kenneth Asselman, who analyzed the hair samples, and the medical students, who helped out with the blood and hair sample collection.

Author contributions

Authors S.V.H., J.V.D., L.M., G.L., G.H., and A.G.V. designed the study and wrote the protocol. Author S.V.H. managed the literature searches and summaries of previous related work. Author P.M. performed the biomarker analysis. Authors S.V.H. and P.M. undertook the statistical analysis, and author P.M. wrote the first draft of the manuscript. All authors contributed to and have approved the final manuscript.

Funding

Funding for this study was provided by the Department of Public Health of Ghent University; the Department of Public Health of Ghent University had no further role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the paper for publication. The authors have no conflict of interest to disclose.