Cannabis sativa

Interviews were conducted by trained research staff in a private setting and data were recorded anonymously, unaccompanied by any unique identifiers. Subjects were first asked the single screening question, “How many times in the past year have you used an illegal drug or used a prescription medication for non-medical reasons?” (where a response of ≥1 is considered positive). If asked to clarify the meaning of “non-medical reasons”, the research associate added "for instance because of the experience or feeling it caused”. After subjects responded to the single screening question, they were asked if they had ever experienced any of a list of problems related to drug use. For this we modified the previously described Short Inventory of Problems-Alcohol and Drug (SIP-AD) questionnaire, which asks about problems ever experienced in the subject’s lifetime related to alcohol or drug use8 (link). We modified this by eliminating the word alcohol from the questions, a modification we hereafter refer to as the Short Inventory of Problems- Drug Use (SIP-DU). In a separate analysis (but in these subjects) we determined the reliability and validity of the SIP-DU as a measure of drug use consequences 9 . The computerized version of the Composite International Diagnostic Interview (CIDI) Substance Abuse Module was used for the assessment of current (12-month) drug use disorders 10 . This structured interview yields a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) diagnosis of drug abuse or dependence. In addition, as part of the CIDI, subjects were asked detailed questions about current (past year) use of illicit drugs (marijuana, cocaine, heroin, stimulants or hallucinogens) and non-medical use of prescription drugs. Following the interview subjects were asked to undergo oral fluid testing for the presence of common drugs of abuse (opiates, benzodiazepines, cocaine, methamphetamines, tetrahydrocannabinol (THC). Once collected, oral fluid was sent to an outside laboratory for analysis using methodology that yields results comparable to urine drug screening (Intercept™ immunoassay, OraSure Technologies, Bethlehem, PA)11 (link)–14 (link). In order to aid in the interpretation of drug test results subjects had been asked, as part of the interview, if they had recently been prescribed any drugs from a list of opiates or benzodiazepines. Because this question was added to the questionnaire during the study, responses were missing from 23 subjects who underwent oral fluid testing. Subjects were not told that they would be asked to undergo drug testing until the interview was complete. After completing the interview, they were compensated and thanked for their participation. They were then asked to undergo oral fluid testing and a second informed consent process was completed. Following the single drug screening question, but before the other assessments, the 10-item Drug Abuse Screening Test (DAST-10) was administered for comparison 4 (link). As part of a parallel study on screening for unhealthy alcohol use, subjects were also asked a single alcohol screening question (preceding the drug screening question), two other brief alcohol screening questionnaires and a calendar based assessment of past-month alcohol consumption (all after the drug screen and prior to the CIDI) 7 (link).