Two commercially available
drug-screening assays were evaluated: the Roche kinetic interaction of microparticles in
solution (KIMS) assay and the Microgenics cloned
enzyme donor immunoassay (CEDIA). Urine samples from known
drug-abuse patients were analyzed for
amphetamines,
barbiturates,
benzodiazepines,
benzoylecgonine,
cannabinoids,
LSD,
methadone and
opiates. Samples with discordant findings for the two assays were analyzed by gas chromatography/mass spectrometry (GC/MS) or gas chromatography/electron capture detection (GC/ECD).
Amphetamines showed 96.0% concordant results, with two false positive findings by CEDIA, three by KIMS and a further two false negatives by KIMS.
Barbiturates showed 99.4% concordant results, with one false negative by KIMS.
Benzodiazepines showed 97.4% concordant results, with two false negatives by KIMS (cutoff 100 microg/L, CEDIA cutoff 300 microg/L).
Benzoylecgonine showed 17.8% concordant positive and 82.2% concordant negative results and no false finding by either assay.
Cannabinoids showed 99.3% concordant results, with one sample negative by KIMS at a cutoff of 50 microg/L and positive by CEDIA (cutoff 25 microg/L). For
LSD, 6.7% of findings were not in agreement.
Methadone showed 97.5% concordant results, with two false positives by CEDIA, and one false positive and one false negative by KIMS.
Opiates showed 96.9% concordant results, with no false KIMS results, but four false positives by CEDIA. The results indicate that the agreement of the CEDIA and KIMS results for the eight drugs is rather good (93.3-100%).