Racial/ethnic disparity in the associations of smoking status with uncontrolled hypertension subtypes among hypertensive subjects

BACKGROUND Racial/ethnic differences in the associations of smoking with uncontrolled blood pressure (BP) and its subtypes (isolated uncontrolled systolic BP (SBP), uncontrolled systolic-diastolic BP, and isolated uncontrolled diastolic BP (DBP)) have not been investigated among diagnosed hypertensive subjects. METHODS A sample of 7,586 hypertensive patients aged ≥18 years were selected from the National Health and Nutrition Examination Survey 1999-2010. Race/ethnicity was classified into Hispanic, non-Hispanic white, and non-Hispanic black. Smoking was categorized as never smoking, ex-smoking, and current smoking. Uncontrolled BP was determined as SBP≥140 or DBP≥90 mm Hg. Isolated uncontrolled SBP was defined as SBP≥140 and DBP<90 mm Hg, uncontrolled SDBP as SBP≥140 and DBP≥90 mm Hg, and isolated uncontrolled DBP as SBP<140 and DBP≥90 mm Hg. Adjusted odds ratios (ORs) with 95% confidence intervals (CIs) of uncontrolled BP and its subtypes were calculated using weighted logistic regression models. RESULTS The interaction effect of race and smoking was significant after adjustment for the full potential confounding covariates (Adjusted p = 0.0412). Compared to never smokers, current smokers were 29% less likely to have uncontrolled BP in non-Hispanic whites (OR = 0.71, 95% CI = 0.56-0.90), although the likelihood for uncontrolled BP is the same for smokers and never smokers in Hispanics and non-Hispanic blacks. Current smokers were 26% less likely than never smokers to have isolated uncontrolled SBP in non-Hispanic whites (OR = 0.74, 95% CI = 0.58-0.95). However, current smoking is associated with an increased likelihood of uncontrolled systolic-diastolic BP in non-Hispanic blacks, and current smokers in this group were 70% more likely to have uncontrolled systolic-diastolic BP than never smokers (OR = 1.70, 95% CI = 1.10-2.65). CONCLUSION The associations between current smoking and uncontrolled BP differed over race/ethnicity. Health practitioners may need to be especially vigilant with non-Hispanic black smokers with diagnosed hypertension.