TY - JOUR

T1 - Correlations and agreement between delta-9-tetrahydrocannabinol (THC) in blood plasma and timeline follow-back (TLFB)-assisted self-reported use of cannabis of patients with cannabis use disorder and psychotic illness attending the CapOpus randomized clinical trial

AU - Hjorthøj, Carsten Rygaard

AU - Fohlmann, Allan

AU - Larsen, Anne-Mette

AU - Arendt, Mikkel

AU - Nordentoft, Merete

N1 - © 2011 The Authors, Addiction © 2011 Society for the Study of Addiction.

PY - 2012

Y1 - 2012

N2 - Aims To assess correlations and agreement between timeline follow-back (TLFB)-assisted self-report and blood samples for cannabis use. Design Secondary analysis of a randomized trial. Setting Copenhagen, Denmark. Participants One hundred and three patients from the CapOpus trial with cannabis use disorder and psychosis, providing 239 self-reports of cannabis use and 88 valid blood samples. Measurements Delta-9-tetrahydrocannabinol (THC), 11-hydroxy-delta-9-tetrahydrocannabinol (11-OH-THC) and 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) detected in plasma using high-performance liquid chromatography with tandem mass spectrometry detection. Self-report of cannabis-use last month by TLFB. Pearson's r, sensitivity and specificity calculated as measures of correlation or agreement. Findings Correlations were strong; r = 0.75 for number of days and r = 0.83 for number of standard joints in the preceding month when excluding outliers. Including outliers, coefficients were moderate to strong (r = 0.49). There were differences in subgroups, mainly inconsistent, depending on inclusion or exclusion of outliers. Sensitivity and specificity for TLFB detecting the presence or absence of cannabis use were 95.7% [95% confidence interval (CI) 88.0-99.1%) and 72.2% (95% CI 46.5-90.3%), respectively. Using 19 days as cut-off on TLFB, they were 94.3% (95% CI 86.0-98.4%) and 94.4% (95% CI 72.2-99.9%), respectively. Area under the receiver operating characteristic (ROC) curve was 0.96. Conclusions Timeline follow-back (TLFB)-assisted self-report of cannabis use correlates highly with plasma-delta-9-tetrahydrocannabinol in patients with comorbid cannabis use disorder and psychosis. Sensitivity and specificity of timeline follow-back appear to be optimized with 19 days as the cut-off point. As such, timeline follow-back may be superior to analysis of blood when going beyond 19 days of recall.

AB - Aims To assess correlations and agreement between timeline follow-back (TLFB)-assisted self-report and blood samples for cannabis use. Design Secondary analysis of a randomized trial. Setting Copenhagen, Denmark. Participants One hundred and three patients from the CapOpus trial with cannabis use disorder and psychosis, providing 239 self-reports of cannabis use and 88 valid blood samples. Measurements Delta-9-tetrahydrocannabinol (THC), 11-hydroxy-delta-9-tetrahydrocannabinol (11-OH-THC) and 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) detected in plasma using high-performance liquid chromatography with tandem mass spectrometry detection. Self-report of cannabis-use last month by TLFB. Pearson's r, sensitivity and specificity calculated as measures of correlation or agreement. Findings Correlations were strong; r = 0.75 for number of days and r = 0.83 for number of standard joints in the preceding month when excluding outliers. Including outliers, coefficients were moderate to strong (r = 0.49). There were differences in subgroups, mainly inconsistent, depending on inclusion or exclusion of outliers. Sensitivity and specificity for TLFB detecting the presence or absence of cannabis use were 95.7% [95% confidence interval (CI) 88.0-99.1%) and 72.2% (95% CI 46.5-90.3%), respectively. Using 19 days as cut-off on TLFB, they were 94.3% (95% CI 86.0-98.4%) and 94.4% (95% CI 72.2-99.9%), respectively. Area under the receiver operating characteristic (ROC) curve was 0.96. Conclusions Timeline follow-back (TLFB)-assisted self-report of cannabis use correlates highly with plasma-delta-9-tetrahydrocannabinol in patients with comorbid cannabis use disorder and psychosis. Sensitivity and specificity of timeline follow-back appear to be optimized with 19 days as the cut-off point. As such, timeline follow-back may be superior to analysis of blood when going beyond 19 days of recall.

U2 - 10.1111/j.1360-0443.2011.03757.x

DO - 10.1111/j.1360-0443.2011.03757.x

M3 - Journal article

C2 - 22151583

SP - 1123

EP - 1131

JO - Addiction

JF - Addiction

SN - 0965-2140

ER -