Jennie B. Jarrett and Linda Hogan are with the St. Margaret Family Medicine Residency Program at the University of Pittsburgh Medical Center. Corey Lyon is with the University of Colorado Family Medicine Residency, Denver. Kate Rowland is with the Rush Copley Family Medicine Residency, Aurora, Illinois.
The European Society of Hypertension practice guideline on HBP monitoring suggests that HBP values < 130/80 mm Hg may be considered normal, while a mean HBP ≥ 135/85 mm Hg is considered elevated.9 The guideline recommends HBP monitoring for three to seven days prior to a patient’s follow-up appointment, with two readings taken one to two minutes apart in the morning and evening.9 In a busy clinic, averaging all of these home values can be time-consuming.
So how can primary care providers accurately and efficiently streamline the process? This study sought to answer that question.
3 of 10 readings = predictive
This multicenter trial compared HBP monitoring to 24-hour ABPM in 286 patients with uncomplicated essential hypertension to determine the optimal percentage of HBP readings needed to diagnose uncontrolled BP (HBP ≥ 135/85 mm Hg). Patients were included if they were diagnosed with uncomplicated hypertension, not pregnant, age 18 or older, and taking three or fewer antihypertensive medications. Patients were excluded if they had a significant abnormal left ventricular mass index (women > 59 g/m2; men > 64 g/m2), coronary artery or renal disease, secondary hypertension, serum creatinine exceeding 1.6 mg/dL, aortic valve stenosis, upper limb obstructive atherosclerosis, or BP > 180/100 mm Hg.
Approximately half of the participants were women (53%). Average BMI was 29.4 kg/m2, and the average number of hypertension medications being taken was 2.4. Medication compliance was verified by a study nurse at a clinic visit.
The patients were instructed to take two BP readings (one minute apart) at home three times daily, in the morning (between 6 am and 10 am), at noon, and in the evening (between 6 pm and 10 pm), and to record only the second reading for seven days. Only the morning and evening readings were used for analysis in the study. The 24-hour ABP was measured every 30 minutes during the daytime hours and every 60 minutes overnight.
The primary outcome was to determine the optimal number of systolic HBP readings above goal (135 mm Hg), from the last 10 recordings, that would best predict elevated 24-hour ABP. Secondary outcomes were various cardiovascular markers of target end-organ damage.
The researchers found that if at least three of the last 10 HBP readings were elevated (≥ 135 mm Hg systolic), the patient was likely to have hypertension on 24-hour ABPM (≥ 130 mm Hg). When patients had less than three HBP elevations out of 10 readings, their mean (± standard deviation [SD]) 24-hour ambulatory daytime systolic BP was 132.7 (± 11.1) mm Hg and their mean systolic HBP value was 120.4 (± 9.8) mm Hg. When patients had three or more HBP elevations, their mean 24-hour ambulatory daytime systolic BP was 143.4 (± 11.2) mm Hg and their mean systolic HBP value was 147.4 (± 10.5) mm Hg.
The positive and negative predictive values of three or more HBP elevations were 0.85 and 0.56, respectively, for a 24-hour systolic ABP of ≥ 130 mm Hg. Three elevations or more in HBP, out of the last 10 readings, was also an indicator for target organ disease assessed by aortic stiffness and increased left ventricular mass and decreased function.
The sensitivity and specificity of three or more elevations for mean 24-hour ABP systolic readings ≥ 130 mm Hg were 62% and 80%, respectively, and for 24-hour ABP daytime systolic readings ≥ 135 mm Hg were 65% and 77%, respectively.