Variation in saliva cotinine as a function of self-reported attempts to reduce cigarette consumption.

RATIONALE: Cotinine is an accurate objective marker of nicotine intake. There is very little information on its stability over time or as a function of self-reported attempts at smoking reduction.
OBJECTIVES: This study aimed to assess the stability of saliva cotinine concentrations over a 3-month period, as a function of self-reported attempts to reduce cigarette consumption, using data from a general population sample of English smokers.
METHODS: Six-hundred and ninety-one smokers from a population sample of English smokers provided saliva samples for cotinine analysis on two occasions 3 months apart. Data on cigarette consumption, whether smokers reported that they were attempting to cut down consumption and concurrent use of nicotine replacement therapy (NRT), were also collected on both occasions.
RESULTS: The 'test-retest' measure of cotinine stability was 0.76, and the simple correlation was 0.73. Smokers not using NRT who reported cutting down on one occasion but not the other showed a small reduction in cigarette consumption at the time they were cutting down (1.1 cig per day, p = 0.013) but no significant difference in saliva cotinine concentrations (mean reduction = 13.4 ng/ml, p = 0.39).
CONCLUSIONS: Saliva cotinine concentrations show moderate-to-high stability within subjects over a 3-month period. Smokers' reports of attempting to cut down their smoking are associated with small daily cigarette consumption decreases but no detectable change in nicotine intake.