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

IntroductionThe effect profile of differing antihypertensive agents is well studied, but minimal data regarding the interaction between hemodynamic response and presenting blood pressure (BP) exist.HypothesisAchievement of target BP is less likely in patients with higher initial BPs.MethodsThis 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.ResultsA 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.ConclusionInitial SBP is not a predictor of the ability to achieve a prespecified target range SBP within 30 minutes.