An Evaluation of Racial Differences in the Classification of Blood Pressure Control after Stroke

Blood pressure (BP) control is important for secondary stroke prevention and there are racial differences in BP control after stroke. BP is often treated based on in-clinic BP measurement; however, casual BP obtained in clinic may be inaccurate. We sought to determine whether race was associated with BP control misclassification in stroke survivors. We followed ischemic/hemorrhagic stroke and transient ischemic attack patients in clinic within 30 days of hospital discharge. Sitting BP was obtained using a standard office automated machine (casual BP). BP was also measured with an automated office BP machine (AOBP), which measures 6 unattended BPs and averages the last 5. OABP has been used to approximate the gold standard 24-hour ambulatory BP (office BP 140/90 = AOBP 135/85). We defined the following categories: concordant control (AOBP < 135/85; casual BP < 140/90), concordant uncontrolled (AOBP ≥ 135/85, casual BP (≥ 140/90); pseudo-resistant hypertension (AOBP < 135/85, casual BP (≥ 140/90), masked-uncontrolled hypertension (AOBP (≥ 135/85; casual BP < 140/90). Multinomial logistic regression was used to assess relationships between race and classification categories, controlling for potential confounders. Among 216 patients, mean age was 59.5 (SD 12.9); 50.5% African American, 21.3% Hispanic (HIS), and 25.5% Non-Hispanic White (NHW). BP control was misclassified in 32.1% of African Americans (17% pseudo-resistant and 16.5% masked uncontrolled); 26.1% of HIS (8.7% and 17.4%); and 20% of NHW (18.2% and 1.8%). In the univariate analysis, there was a trend toward an association between race and BP category (p = 0.06). Race was significantly associated with misclassification in the regression analysis. The odds ratio for masked uncontrolled compared to concordant controlled BP was 12.2 (95% CI 1.5, 99.2) for AA compared to NHW and 9.9 (95% CI 1.1, 87.4) for HIS compared to NHW. These findings highlight the challenges in classifying control of BP and thus appropriately treating hypertension after stroke. Accurate tools for BP measurement including AOBP, home BP, and ambulatory BP monitoring should be utilized to optimize BP treatment after stroke.