Validation of self-reported smoking status using saliva cotinine: A rapid semiquantitative dipstick method

Abstract

Purpose: This study evaluated the performance characteristics of a novel rapid method for verifying smoking status in individuals by measurement of cotinine,the primary metabolite of nicotine,in saliva samples using an immunochromatographic strip in a "dipstick" format compared with liquid chromatography/mass spectrometry (LC/MS). Materials and Methods: A prospective comparison was made of smoking status as determined by measurement of cotinine in urine by LC/MS (the gold standard) and in saliva using a semiquantitative dipstick assay that uses cotinine-specific monoclonal antibodies attached to gold particles and a series of avidity traps to measure cotinine levels (saliva NicAlert®). One hundred seventy-two individuals from a family practice/general medical setting agreed to participate after informed consent and institutional review board approval. Saliva NicAlert® tests were done by untrained operators who followed written directions. Results: Comparison of smoking status as determined by urine cotinine measurement by LC/MS (50 ng/mL cutoff) with the saliva strip test results,averaged over the two operators,indicated that the saliva test strip results had a sensitivity of 99% and a specificity of 96%. Saliva NicAlert® also identified four smokers who reported being nonsmokers but were confirmed to be smokers by LC/MS. Conclusions: The saliva NicAlert® assay seems to be a valid,highly sensitive, and specific method for validating self-reported smoking status and may have clinical applications in selected medical settings. Copyright © 2007 American Association for Cancer Research.