A Home Blood Pressure Monitor Equipped With a Graphic Function Facilitates Faster Blood Pressure Control than the Conventional Home Blood Pressure Monitor

Abstract

In this study, we evaluated whether antihypertensive therapy using a home blood pressure monitor (HBPM) equipped with a graphic display of weekly and monthly averaged blood pressure (BP) can obtain better BP control than the conventional HBPM. Sixty‐five hypertensive outpatients who had HBP >135/85 mm Hg were enrolled by 8 doctors in 2 different hospitals. The patients were randomly assigned either a graph‐equipped HBPM (graph‐equipped HBPM group; n=33) or an HBPM without the graph function (conventional HBPM group; n=32). The patients were treated with antihypertensive medications targeting HBP <135/85 mm Hg. After 2 months, the home systolic BP level was lower in the graph‐equipped HBPM group than in the conventional HBPM group (141.3±15.4 vs 147.7±10.8 mm Hg; P<.05); its reduction was significantly larger in the former group (11.9 vs 5.6 mm Hg; P<.05). Using an HBP device with a graphic display could accelerate the achievement of BP control.

Home blood pressure (HBP) often shows variability between successive readings and between morning and evening blood pressure (BP) values. ¹ , ² Patients are often afraid of hypotension due to overmedication, and physicians often hesitate to increase the dosages of hypertensive medications for this reason. Therefore, we hypothesized that an additional display function to visualize the change in weekly average BP values might assist physicians in their therapeutic decisions and help improve BP control.

The purpose of this study was to evaluate whether BP control using an HBP monitor (HBPM) equipped with a weekly averaged BP graphic display can lead to better BP control and a higher proportion of patients achieving the target BP compared with a conventional monitor.

Methods

This study was conducted by 8 physicians at 2 hospitals in Japan. We screened 81 hypertensive outpatients who were taking antihypertensive medications. After reviewing the results of the 2‐week screening measurement, we excluded 12 patients who had controlled HBP (<135/85 mm Hg), 3 patients who refused HBP measurement, and 1 patient who stopped visiting his physician. Sixty‐five patients with uncontrolled HBP (>135/85 mm Hg) were thus enrolled in the final study group.

Each participating institute received approval for the study from the institutional review board of the Jichi Medical University. Written informed consent was obtained from all of the patients who were enrolled in this study.

All of the patients were randomly assigned to either a group using an HBPM with a graphic display of weekly averaged BP (graph‐equipped HBPM; n=33) or a group using an HBPM without this function (conventional HBPM; n=32). The study coordinator in each institute allocated the study patients using a computerized random number with the computer SPSS software, version 11.0J (SPSS Inc, Chicago, IL).

For each patient, physicians were asked to evaluate the HBP (average of morning and evening BP) and to attempt to reduce it to below 135/85 mm Hg in 6 months using any antihypertensive drugs they considered appropriate.

Home BP was measured using a validated upper arm cuff‐oscillometric device. ³ The device was equipped with BP memory in order to recall measurements with displays of numeric values and graphs of weekly averaged BPs and pulse rates (Figure 1). In the conventional HBPM group, HBP was measured using the same device but modified to deactivate the weekly averaged values and graph‐display function (a plastic plate was attached to the console to hide these functions). Thus, physicians in this group could observe only each BP value.

Figure 1.

  Analytical functions on the graph‐equipped home blood pressure (BP) monitor. Left panel: a transition of weekly BP (the dotted line shows the target home BP [135/85 mm Hg]). Right panel: weekly BP (systolic BP, diastolic BP, and pulse rate).

HBP was measured on the nondominant upper arm in the sitting position after 2 minutes of rest. In both groups, the HBPM measurements were automatically repeated 3 times per occasion with 15‐second intervals. Morning BP was measured within 1 hour after waking, after urination, and before breakfast and taking antihypertensive medication. ⁴ Evening BP was measured immediately before going to bed. HBP was defined by an average of morning and evening BP over the 2 weeks immediately before visiting the physician’s office.

Clinic BP was measured 3 times per occasion after a rest of at least 5 minutes in the sitting position using the same HBPM device, which patients brought with them to the clinic.

Results

The mean ± SD age was 67±13 years, 46% of participants were male, and the mean number of medicine was 1.9±1.0. The 2 groups were similar in terms of age, sex, demographic characteristics, antihypertensive drug use before enrollment, and prevalence of coexisting cardiovascular conditions.

Home systolic BP was similar in both groups (the graph‐equipped HBPM group, 153.2±14.9 mm Hg; the conventional HBPM group, 153.1±12.3 mm Hg) at baseline. Home systolic BP in the graph‐equipped HBPM group was significantly lower than that in the conventional HBPM group after 2 months of treatment (141.3±15.4 vs 147.7±10.8 mm Hg, P<.05; Figure 2). The reduction of home systolic BP in the graph‐equipped HBPM group was also significantly larger than that in the conventional HBPM group after 2 months (11.9 vs 5.6 mm Hg; P<.05). The percentage of patients with HBP below 135/85 mm Hg in the graph‐equipped HBPM group was higher than that in the conventional HBPM group after 2 months (41% vs 13%, P<.05; Figure 2), 4 months (40% vs 11%, P<.05; Figure 2), and 5 months (37% vs 16%, P<.05; Figure 2) of treatment.

Figure 2.

  Blood pressure (BP) levels in the study population. Filled circles, black bars=graph‐equipped home BP monitoring (HBPM) group; open circles, white bars=conventional HBPM group. *P<.05 vs the conventional group by an unpaired t test or the chi‐square test. (A) change of home systolic BP, (B) proportion of patients achieving BP goal, (C) change of morning systolic BP, (D) change of evening systolic BP.

Clinic systolic BP in the graph‐equipped HBPM group was significantly lower than that in the conventional HBPM group after 3 months of treatment (143.3 vs 153.0 mm Hg; P<.05).

Patients in the graph‐equipped HBPM group were more medicated than those in the conventional HBPM group after 5 months (3.58 vs 2.73 drugs; P<.03) and 6 months (3.74 vs 2.76 drugs; P<.02) of treatment.

Discussion

In this study, we showed that antihypertensive treatments using an HBP device with a graphic display of weekly averaged BP values can lead to faster BP control than that using the conventional device.

The faster BP control in the graph‐equipped HBPM group could be explained as follows. First, by referring to the screen showing the graph and the mean BP values, both the physician and the patient were able to determine at a glance whether the HBP was being controlled sufficiently. If the patient’s BP was not being controlled below 135/85 mm Hg, this fact was clearly presented on the screen in graphic and numeric fashion. The “easy‐to‐read” display helped to convince patients of the need to dose‐up their antihypertensive medications.

Second, physicians and patients often are concerned about temporary hypotension due to over‐dosage. Patients displaying a strong white‐coat effect are particularly vulnerable to hypotension, since they may be over‐dosed based on their inflated clinic BP levels. ⁵ Even if the physician refers to the HBP in such cases, he/she may not be confident about this data due to its considerable variation, and therefore may not be able to use it in making a dosing decision.

Conclusions

BP management using an HBP device with a graphic display of weekly averaged BP values can facilitate faster BP control.