Smokeless tobacco use and fractional exhaled nitric oxide in men in a national survey.

BACKGROUND: Tobacco use is an important risk for asthma and increases asthma severity. Fractional exhaled nitric oxide (FeNO) is used as a noninvasive biomarker of eosinophilic airway inflammation. Substantial numbers of men use smokeless tobacco. The effect of use of smokeless tobacco on FeNO is not known.

OBJECTIVE: To estimate the association between use of smokeless tobacco and FeNO among US men.

METHODS: The National Health and Nutrition Examination Survey 2007-2012 was analyzed to assess association of use of smokeless tobacco and FeNO levels in parts per billion in US men. Participants were categorized by smoking status and use of snuff or chewing tobacco in the previous 5 days. FeNO was measured using a device that relies on an electrochemical sensor.

RESULTS: In 3,791 male nonsmokers without asthma, weighted mean natural logarithm FeNO by exposure to smokeless tobacco was 2.81 (geometric mean FeNO, 16.59 ppb; 95% CI, 2.77-2.85) in unexposed and 2.66 (geometric mean, 14.30 ppb; 95% CI, 2.55-2.77) in the exposed. In weighted linear regression analyses, use of smokeless tobacco was associated with significantly lower natural logarithm FeNO after controlling for age and race (black vs nonblack) (coefficient, -0.124; SE, 0.056; P = .03; 95% CI, -0.237 to -0.011). Results were unchanged after additionally controlling for recent nitric oxide-rich vegetable consumption and upper respiratory tract infection (coefficient, -0.118; SE, 0.055; P = .04; 95% CI, -0.228 to -0.007).

CONCLUSIONS: Use of smokeless tobacco was associated with lower mean natural logarithm FeNO levels in nonsmokers with no history of asthma. Interpretation of FeNO should consider all forms of tobacco use.