{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T21:29:33Z","timestamp":1784150973220,"version":"3.55.0"},"reference-count":37,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2012,2,13]],"date-time":"2012-02-13T00:00:00Z","timestamp":1329091200000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Addiction"],"published-print":{"date-parts":[[2012,6]]},"abstract":"<jats:title>ABSTRACT<\/jats:title><jats:p><jats:bold>Aims\u2003<\/jats:bold> To assess correlations and agreement between timeline follow\u2010back (TLFB)\u2010assisted self\u2010report and blood samples for cannabis use.<\/jats:p><jats:p><jats:bold>Design\u2003<\/jats:bold> Secondary analysis of a randomized trial.<\/jats:p><jats:p><jats:bold>Setting\u2003<\/jats:bold> Copenhagen, Denmark.<\/jats:p><jats:p><jats:bold>Participants\u2003<\/jats:bold> One hundred and three patients from the CapOpus trial with cannabis use disorder and psychosis, providing 239 self\u2010reports of cannabis use and 88 valid blood samples.<\/jats:p><jats:p><jats:bold>Measurements\u2003<\/jats:bold> Delta\u20109\u2010tetrahydrocannabinol (THC), 11\u2010hydroxy\u2010delta\u20109\u2010tetrahydrocannabinol (11\u2010OH\u2010THC) and 11\u2010nor\u2010delta\u20109\u2010tetrahydrocannabinol\u20109\u2010carboxylic acid (THC\u2010COOH) detected in plasma using high\u2010performance liquid chromatography with tandem mass spectrometry detection. Self\u2010report of cannabis\u2010use last month by TLFB. Pearson's <jats:italic>r<\/jats:italic>, sensitivity and specificity calculated as measures of correlation or agreement.<\/jats:p><jats:p><jats:bold>Findings\u2003<\/jats:bold> Correlations were strong; <jats:italic>r<\/jats:italic>\u2003=\u20030.75 for number of days and <jats:italic>r<\/jats:italic>\u2003=\u20030.83 for number of standard joints in the preceding month when excluding outliers. Including outliers, coefficients were moderate to strong (<jats:italic>r<\/jats:italic>\u2003=\u20030.49). 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\u201399.1%) and 72.2% (95% CI 46.5\u201390.3%), respectively. Using 19 days as cut\u2010off on TLFB, they were 94.3% (95% CI 86.0\u201398.4%) and 94.4% (95% CI 72.2\u201399.9%), respectively. Area under the receiver operating characteristic (ROC) curve was 0.96.<\/jats:p><jats:p><jats:bold>Conclusions\u2003<\/jats:bold> Timeline follow\u2010back (TLFB)\u2010assisted self\u2010report of cannabis use correlates highly with plasma\u2010delta\u20109\u2010tetrahydrocannabinol in patients with comorbid cannabis use disorder and psychosis. Sensitivity and specificity of timeline follow\u2010back appear to be optimized with 19 days as the cut\u2010off point. As such, timeline follow\u2010back may be superior to analysis of blood when going beyond 19 days of recall.<\/jats:p>","DOI":"10.1111\/j.1360-0443.2011.03757.x","type":"journal-article","created":{"date-parts":[[2011,12,9]],"date-time":"2011-12-09T14:49:37Z","timestamp":1323442177000},"page":"1123-1131","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":55,"title":["Correlations and agreement between delta\u20109\u2010tetrahydrocannabinol (THC) in blood plasma and timeline follow\u2010back (TLFB)\u2010assisted self\u2010reported use of cannabis of patients with cannabis use disorder and psychotic illness attending the CapOpus randomized clinical trial"],"prefix":"10.1111","volume":"107","author":[{"given":"Carsten 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