Study objective: We determine the frequency of elevated blood pressure (BP) readings in the emergency department (ED), the proportion of patients with prior or subsequent diagnosis of hypertension assigned in other settings, and the association between ED BP levels and cardiovascular outcomes after ED discharge.
Methods: This was a retrospective cohort study using electronic medical records for all adults treated and released from a large-volume ED in 2016 that were linked to administrative records for all health care encounters in the province for 2 years before and after the index ED visit. The primary outcome measure was a composite of stroke or transient ischemic attack, acute coronary syndrome, new heart failure, or death.
Results: Of 30,278 adults treated and released from the ED, 14,717 (48.6%) had elevated BP readings; 10,732 (72.9%) had no prior diagnosis of hypertension. Of the 3,480 patients with no prior diagnosis of hypertension but an ED BP greater than or equal to 160/100 mm Hg, 907 (26.1%) subsequently received a diagnosis of chronic hypertension or were prescribed antihypertensive therapy in other settings within 2 years. Among patients without a history of hypertension, those with an ED BP greater than or equal to 160/100 mm Hg were more likely to meet the composite outcome (stroke, transient ischemic attack, acute coronary syndrome, heart failure, or death) in the subsequent year (3.3% versus 2.5%) or 2 years (5.9% versus 3.8%) than those with ED BPs 120 to 139/80 to 89 mm Hg; however, after adjusting for age, sex, diabetes, atrial fibrillation, and prior cardiovascular disease, their risk was not elevated (adjusted hazard ratio 0.84; 95% confidence interval 0.71 to 1.004 during 2 years).
Conclusion: Elevated BP readings in the ED are common and are often the first time hypertension is detected; however, they were not associated with adverse cardiovascular outcomes within 2 years of the visit.
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