Characteristics of Patients That Do Not Initially Respond to Intravenous Antihypertensives in the Emergency Department: Subanalysis of the CLUE Trial

INTRODUCTION Hypertensive emergency has a high mortality risk and the treatment goal is to quickly lower blood pressure with intravenous (IV) medications. Characteristics that are associated with non-response to IV antihypertensives have not been identified. The objective is to identify patient characteristics associated with resistance to IV antihypertensives. METHODS This was a subanalysis of patients enrolled in the previously described comparative effectiveness trial of IV nicardipine vs. labetalol use in the emergency department (CLUE) study, a randomized trial of nicardipine vs. labetalol. Non-responders were defined as those patients who did not achieve target systolic blood pressure (SBP), as set by the treating physician, within thirty minutes of IV antihypertensive medication, +/- 20mmHg. Stepwise logistic regression was used to identify covariates associated with the measurement outcomes. RESULTS CLUE enrolled 226 patients, 52.7% female, 76.4% black, mean age of 52.6±14.6 years, of whom 110 were treated with nicardipine and 116 with labetalol. The median (IQR) initial systolic blood pressure was 211mmHg (198, 226), 210 (200, 230), and 211mmHg (198, 226), for the total, non-responder, and responder cohorts, respectively (p-value=0.65, 95% CI [-5.8-11.3]). Twenty-nine were non-responders, 9 in the nicardipine and 20 in the labetalol group. In univariate analysis, several symptoms suggestive of end organ damage were associated with non-response. After multiple variable logistic regression (AUC = 0.72), treatment with labetalol (OR 2.7, 95% CI [1.1-6.7]), history of stroke (OR 5.4, 95% CI [1.6-18.5]), and being male (OR 3.3, 95% CI [1.4-8.1]) were associated with failure to achieve target blood pressure. CONCLUSION Male gender and history of previous stroke are associated with difficult to control blood pressure.