Study objective: We determine the reproducibility of increased blood pressure measurements among adults in the emergency department or minor injury clinic.
Methods: The study was conducted at Kaiser Permanente Medical Center in Hayward, CA, a large, group-model health maintenance organization providing capitated insurance coverage. All patients were included in the study who had no current diagnosis of hypertension but had increased blood pressure on their presentation to the ED or minor injury clinic during the 2-month study period. The staff was asked to repeat the blood pressure later during the index visit and provide these patients with written instructions to return for additional repeat measures. We compared blood pressures taken in the ED to measurements before and after the ED visit.
Results: Four hundred seven patients were included in the study. Of the initial elevated blood pressures, 211 (51.8%) were stage 1 elevation, 147 (36.1%) were stage 2, and 49 (12.0%) were stage 3 by criteria of the Joint National Committee on Hypertension. Sixty-five percent of patients had repeat measures in the clinic during our 5-month follow-up period, despite active outreach and reminders. Seventy percent of those who had repeat blood pressure documented had at least 1 increased blood pressure after their ED visit. The proportion of patients with at least 1 abnormal blood pressure on subsequent measurement increased with increasing stage of initial blood pressure (64.4% for stage 1, 77.1% for stage 2, 97.1% for stage 3), but was similar for patients with and without pain as a chief complaint and was similar for patients seen in the ED compared with patients seen in urgent care. Compared with blood pressures taken during the ED visit, matched blood pressures taken before or after showed no statistically significant differences.
Conclusion: Increased blood pressure is common among emergency or urgent care patients without a history of current hypertension, and most of these will have mixed or consistently abnormal results on repeat measures. Patients should be referred for repeat measures after a single abnormal measure in the ED.