Seated systolic and diastolic BPs were measured using a mercury sphygmomanometer according to the American Heart Association and the Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC 7). 13,14 Up to 3 measurements were averaged for systolic and diastolic pressures. Patients were considered hypertensive if they reported physician diagnosis of hypertension, current BP-reducing medication use, or had systolic BP ≥140 mm Hg and diastolic BP ≥90 mm Hg based on JNC 7 criteria.
13Abstract-Hypertension is a major public health problem. Identifying novel risk factors for hypertension, including widely prevalent environmental exposures, is therefore important. Active smoking is a well-known risk factor for hypertension and cardiovascular diseases. However, there are no studies investigating the relationship between secondhand smoke exposure, measured objectively by serum cotinine, and high blood pressure among never smokers. We examined 2889 never smokers from the National Health and Nutrition Examination Survey 2005-2008. Our exposure of interest was secondhand smoke exposure among never smokers, estimated by serum cotinine level, and our main outcome was hypertension (n=1004). We found that in never smokers, higher serum cotinine levels were positively associated with hypertension. In comparison with those with serum cotinine levels ≤0.025 ng/mL, the multivariable odds ratio (95% confidence interval) of hypertension among those with serum cotinine levels ≥0.218 ng/mL was 1.44 (1.01-2.04). In addition, higher serum cotinine was positively associated with mean change in systolic blood pressure (odds ratio [95% confidence interval], 3.24 [0.86-5.63]; P=0.0061). However, no association was present with diastolic blood pressure. In conclusion, in never smokers, higher secondhand smoke exposure measured objectively by serum cotinine levels was found to be associated with systolic blood pressure and hypertension independent of age, sex, ethnicity, education, alcohol drinking, body mass index, glycohemoglobin, total cholesterol, and other confounders. Briefly, the serum sample was spiked with methyl-D3 cotinine as an internal standard, and after an equilibration period, the sample was applied to a basified solid-phase extraction column. Cotinine was extracted off the column with methylene chloride, the organic extract was concentrated, and the residue was injected onto a short, C18 high-performance liquid chromatography column. The eluant from these injections was monitored by atmospheric pressure chemical ionization-tandem mass spectrometry, and the m/z 80 daughter ion from the m/z 177 quasimolecular ion was quantitated, along with additional ions for the internal standard, external standard, and for confirmation. Cotinine concentrations were derived from the ratio of native/labeled cotinine in the sample, by comparisons to a standard curve. Detailed description of serum cotinine measurement in NHANES is available online.12 Serum total cholesterol was...