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.