Random and systematic errors in case-control studies calculating the injury risk of driving under the influence of psychoactive substances.

Between 2006 and 2010, six population based case-control studies were conducted as part of the European research-project DRUID (DRiving Under the Influence of Drugs, alcohol and medicines). The aim of these case-control studies was to calculate odds ratios indicating the relative risk of serious injury in car crashes. The calculated odds ratios in these studies showed large variations, despite the use of uniform guidelines for the study designs.

Repeatability of oral fluid collection methods for THC measurement.

Study Objectives: To determine the influence of sample collection for two different collection methods on THC concentrations and to compare THC concentrations collected by both methods.

Methods: A total of 136 pairs of oral fluid samples from subjects who had recently smoked Cannabis were obtained by the non-acidic Statsure oral fluid collection device and by ordinary spit tubes. Oral fluid was analyzed for THC by LC-MS/MS.