BIOCHEMICAL VALIDATION OF SMOKING STATUS - PROS, CONS, AND DATA FROM 4 LOW-INTENSITY INTERVENTION TRIALS

Biochemical validation of smoking status has long been considered esse ntial, but recent reports have questioned its utility in certain kinds of field trials. We describe efforts to biochemically validate self-r eports of smoking cessation from participants in four large-scale rand omized trials in outpatient clinics, hospitals, worksites, and dental clinics. These studies included over 5,000 adult smokers who participa ted in the population-based low-intensity intervention evaluations. At a 1-year follow-up, 798 subjects reported no tobacco use. We attempte d to verify these reports using saliva cotinine/carbon monoxide valida tion procedures. Overall, there was a moderately high nonparticipation rate (27%), a low disconfirmation rate (4%), and a high self-reported relapse rate (12%) in the interval between survey and biochemical val idation. There were no differences between intervention and control co nditions on any of the above variables. Longer durations of self-repor ted abstinence were strongly related to increased probability of bioch emical confirmation. Differences in results across projects were relat ed to how biochemical validation was conducted. These results, as well as statistical power considerations, raise questions about whether bi ochemical validation procedures are practical, informative, or cost-ef fective in such population-based, low-intensity intervention research.