Minor recurrent aphthous stomatitis and smoking: an epidemiological study measuring plasma cotinine

OBJECTIVE: To compare blood cotinine levels between a group of patients with minor recurrent aphthous stomatitis (RAS) and a group representative of the general population, matched for age and gender. SETTING: Although smoking has been implicated as a protective factor in RAS, few studies have compared the prevalence of smoking in RAS patients with population controls. Cotinine is a smoking derivative with a long half-life in the circulation. Measurement of plasma cotinine levels provides an accurate and objective measurement of an individual's cigarette consumption METHODS: Blood samples were taken from 84 RAS patients and 81 controls. A microplate enzyme immunoassay (EIA) was used to detect plasma cotinine levels. RESULTS: The number of RAS patients [2 (2.4%)] who were smokers (plasma cotinine >25 mug ml(-1)) was significantly lower than in the control group [12 (14.8%); P=0.00102]. Furthermore, the mean cotinine level amongst smokers in the RAS group was significantly lower than in smokers in the control group (P = 0.0068). CONCLUSION: This study shows that a group of RAS patients is significantly less likely to contain smokers than a matched control population, and among smokers the level of cigarette use was significantly lower in RAS patients than the control population. The perceived negative association between RAS and smoking was supported by this epidemiological study.