Varying results for immunoassay screening kits for cotinine level.

Our earlier study found that although enzyme-linked immunosorbent analysis (ELISA) screening assays for urine cotinine indicated use in former smoking treatment patients who reported abstinence, this finding was sometimes incorrect when validated against gas chromatography/mass spectrometry (GC/ MS; P. Gariti, A. I. Alterman, R. Ehrmann, F. D. Mulvaney, & C. P. O'Brien, 2002). In the current validation study, separate urine samples of 71 of these same patients were reanalyzed by an independent laboratory in blinded fashion using a screening enzyme immunoassay (EIA) analysis and GC/MS confirmation. EIA results showed almost total agreement with confirmatory testing. The findings indicate that use of screening ELISA/EIA for urine cotinine can detect unreported cases of smoking in former patients, but that care is needed in selecting a laboratory for conducting these tests.