Hypothesis on interferences in kinetic interaction of microparticles in solution (KIMS) technology

The present paper describes an evaluation of the interferences found with an immunochemical drug test performed during a workplace control. During the period 1993 - 2003 more than 200,000 urine samples from workers were examined by the Italian Air Force. Samples were screened for drugs of abuse ( opiates, cocaine, cannabinoids, amphetamines, methadone) using an immunochemical technique ( Roche, kinetic interaction of microparticles in solution, KIMS). A total of 520 positive samples were sent to the Forensic Toxicology Laboratory for confirmation by gas chromatography/mass spectrometry (GC/MS). Approximately 39% of these were found to be true positives. For the remaining samples, pharmacological therapy in subjects was estimated to evaluate possible interferences due to medicine intake. Our study showed a high frequency of false-positive results with this immunochemical technique, mainly for the cannabinoid and amphetamine groups. Recurrent references to some medicines during subject anamnesis were noted.