Verification of smoking status by thiocyanate in unrefrigerated, mailed saliva samples.

A simple method of obtaining an unbiased verification of smoking status was developed for use in a randomized clinical trial. At the end of smoking cessation intervention for pregnant women, each participant mailed a saliva sample to a laboratory for the determination of thiocyanate. For comparison, salivary thiocyanate also was measured by a standard collection method in a reference group of non-study women who did not smoke during pregnancy. Although there may have been up to a 1-week delay between collection and analysis, results show that thiocyanate from unrefrigerated, mailed samples of saliva distinguishes reported smokers from nonsmokers, is positively associated with the amount of smoking, and is negatively associated with the length of cessation. These study findings are consistent with results from other studies in which samples of serum or saliva were collected and shipped under conditions requiring the presence of a staff member. The ability to perform an unbiased smoking status verification using a simple, inexpensive, and noninvasive collection method expands study possibilities, as it eliminates the need for direct, face-to-face contact with study subjects, and for being at their location.