Impact of initial blood pressure on antihypertensive response in patients with acute hypertension.

INTRODUCTION: The effect profile of differing antihypertensive agents is well studied, but minimal data regarding the interaction between hemodynamic response and presenting blood pressure (BP) exist.

HYPOTHESIS: Achievement of target BP is less likely in patients with higher initial BPs.

METHODS: This is a substudy of the multicenter safety and efficacy Evaluation of intravenous Cardene (nicardipine) and Labetalol Use in the Emergency department (CLUE) trial that randomized patients to Food and Drug Administration-recommended intravenous dosing of nicardipine or labetalol to reach a physician predefined systolic BP (SBP) and target range (TR) of ±20 mm Hg within 30 minutes. The proportion achieving TR was assessed as a function of initial SBP, and dichotomized comparisons were made using median SBP. Likelihood of a final BP within TR was modeled using logistic regression with forced inclusion of initial BP as a categorical variable.

RESULTS: A total 223 patients were enrolled; 115 (51.6%) had an initial SBP greater than the median 202 mm Hg. The median SBP (interquartile range) of the high BP group was 218 (210-228) mm Hg vs the low BP group 190 (182-197) mm Hg (P < 0.0001). No groupwise differences existed except that the high group had higher mean (SD) serum creatinine level at baseline (3.1 [3.9] vs 1.9 [2.3], P = .008). The proportion of patients achieving SBP within TR at 30 minutes did not differ (85.2% [98 of 115] vs 88.9% [96 of 108], P = .42). Randomization to nicardipine (odds ratio = 2.85; 95% confidence interval, 1.16-7.01), but not initial SBP (odds ratio = 0.60; 95% confidence interval, 0.25-1.44), was associated with achievement of target SBP at 30 minutes.

CONCLUSION: Initial SBP is not a predictor of the ability to achieve a prespecified target range SBP within 30 minutes.