Validation of a new algorithm for the BPM-100 electronic oscillometric office blood pressure monitor

Patient factors, but not provider and health care system factors, predict medication adherence in hypertensive black men

The problem of medication adherence is pronounced in hypertensive black men. However, factors influencing their adherence are not well understood. This secondary analysis of the ongoing Counseling African Americans to Control Hypertension (CAATCH) randomized clinical trial investigated the patient, provider, and health care system factors associated with medication adherence among hypertensive black men. Participants (N=253) were aged 56.6±11.6 years, earned <$20,000 yearly (72.7%), and almost one half were on Medicaid (44%). Mean systolic blood pressure was 148.7±15.8 mm Hg and mean diastolic blood pressure was 92.7±9.8 mm Hg. Over one half of participants (54.9%) were nonadherent. In a hierarchical regression analysis, the patient factors that predicted medication adherence were age, self-efficacy, and depression. The final model accounted for 32.1% of the variance (F=7.80, df 10, 165, P<.001). In conclusion, age, self-efficacy, and depression were associated with antihypertensive medication adherence in black men followed in Community/Migrant Health Centers. Age is a characteristic that may allow clinicians to predict who may be at risk for poor medication adherence. Depression can be screened for and treated. Self-efficacy is modifiable and its implications for practice would be the development of interventions to increase self-efficacy in black men with hypertension.

Why use automated office blood pressure measurements in clinical practice?

Automated office blood pressure (AOBP) measurement with the patient resting alone in a quiet examining room can eliminate the white-coat effect associated with conventional readings taken by manual sphygmomanometer. The key to reducing the white-coat response appears to be multiple blood pressure (BP) readings taken in a non-observer office setting, thus eliminating any interaction that could provoke an office-induced increase in BP. Furthermore, AOBP readings have shown a higher correlation with the mean awake ambulatory BP compared with BP readings recorded in routine clinical practice. Although there is a paucity of studies connecting AOBP with organ damage, AOBP values were recently found to be equally associated with left ventricular mass index as those of ambulatory BP. This concludes that in contrast to routine manual office BP, AOBP readings compare favourably with 24-hour ambulatory BP measurements in the appraisal of cardiac remodelling and, as such, could be complementary to ambulatory readings in a way similar to home BP measurements.

Automated office blood pressure

Manual blood pressure (BP) is gradually disappearing from clinical practice with the mercury sphygmomanometer now considered to be an environmental hazard. Manual BP is also subject to measurement error on the part of the physician/nurse and patient-related anxiety which can result in poor quality BP measurements and office-induced (white coat) hypertension. Automated office (AO) BP with devices such as the BpTRU (BpTRU Medical Devices, Coquitlam, BC) has already replaced conventional manual BP in many primary care practices in Canada and has also attracted interest in other countries where research studies using AOBP have been undertaken. The basic principles of AOBP include multiple readings taken with a fully automated recorder with the patient resting alone in a quiet room. When these principles are followed, office-induced hypertension is eliminated and AOBP exhibits a much stronger correlation with the awake ambulatory BP as compared with routine manual BP measurements. Unlike routine manual BP, AOBP correlates as well with left ventricular mass as does the awake ambulatory BP. AOBP also simplifies the definition of hypertension in that the cut point for a normal AOBP (< 135/85 mm Hg) is the same as for the awake ambulatory BP and home BP. This article summarizes the currently available evidence supporting the use of AOBP in routine clinical practice and proposes an algorithm in which AOBP replaces manual BP for the diagnosis and management of hypertension.

Conventional versus automated measurement of blood pressure in primary care patients with systolic hypertension: randomised parallel design controlled trial

OBJECTIVE

To compare the quality and accuracy of manual office blood pressure and automated office blood pressure using the awake ambulatory blood pressure as a gold standard.

DESIGN

Multi-site cluster randomised controlled trial.

SETTING

Primary care practices in five cities in eastern Canada.

PARTICIPANTS

555 patients with systolic hypertension and no serious comorbidities under the care of 88 primary care physicians in 67 practices in the community.

INTERVENTIONS

Practices were randomly allocated to either ongoing use of manual office blood pressure (control group) or automated office blood pressure (intervention group) using the BpTRU device. The last routine manual office blood pressure (mm Hg) was obtained from each patient's medical record before enrollment. Office blood pressure readings were compared before and after enrollment in the intervention and control groups; all readings were also compared with the awake ambulatory blood pressure.

MAIN OUTCOME MEASURE

Difference in systolic blood pressure between awake ambulatory blood pressure minus automated office blood pressure and awake ambulatory blood pressure minus manual office blood pressure.

RESULTS

Cluster randomisation allocated 31 practices (252 patients) to manual office blood pressure and 36 practices (303 patients) to automated office blood pressure measurement. The most recent routine manual office blood pressure (149.5 (SD 10.8)/81.4 (8.3)) was higher than automated office blood pressure (135.6 (17.3)/77.7 (10.9)) (P < 0.001). In the control group, routine manual office blood pressure before enrollment (149.9 (10.7)/81.8 (8.5)) was reduced to 141.4 (14.6)/80.2 (9.5) after enrollment (P < 0.001/P = 0.01), but the reduction in the intervention group from manual office to automated office blood pressure was significantly greater (P < 0.001/P = 0.02). On the first study visit after enrollment, the estimated mean difference for the intervention group between the awake ambulatory systolic/diastolic blood pressure and automated office blood pressure (-2.3 (95% confidence interval -0.31 to -4.3)/-3.3 (-2.7 to -4.4)) was less (P = 0.006/P = 0.26) than the difference in the control group between the awake ambulatory blood pressure and the manual office blood pressure (-6.5 (-4.3 to -8.6)/-4.3 (-2.9 to -5.8)). Systolic/diastolic automated office blood pressure showed a stronger (P < 0.001) within group correlation (r = 0.34/r = 0.56) with awake ambulatory blood pressure after enrollment compared with manual office blood pressure versus awake ambulatory blood pressure before enrollment (r = 0.10/r = 0.40); the mean difference in r was 0.24 (0.12 to 0.36)/0.16 (0.07 to 0.25)). The between group correlation comparing diastolic automated office blood pressure and awake ambulatory blood pressure (r = 0.56) was stronger (P < 0.001) than that for manual office blood pressure versus awake ambulatory blood pressure (r = 0.30); the mean difference in r was 0.26 (0.09 to 0.41). Digit preference with readings ending in zero was substantially reduced by use of automated office blood pressure.

CONCLUSION

In compliant, otherwise healthy, primary care patients with systolic hypertension, introduction of automated office blood pressure into routine primary care significantly reduced the white coat response compared with the ongoing use of manual office blood pressure measurement. The quality and accuracy of automated office blood pressure in relation to the awake ambulatory blood pressure was also significantly better when compared with manual office blood pressure. Trial registration Clinical trials NCT 00214053.

Manual and automated office measurements in relation to awake ambulatory blood pressure monitoring

BACKGROUND

Automated blood pressure (BP) devices are commonly used in doctor's offices. How BP measured on these devices relates to ambulatory BP monitoring is not clear.

OBJECTIVE

To assess how well office-based manual and automated BP predicts ambulatory BP.

METHODS

Using data on 654 patients, we assessed how well sphygmomanometer measurements and measurements taken with an automated device (BpTRU) predicted results on ambulatory BP monitoring. We assess positive and negative predictive values and overall accuracy. We look at different cut-points for systolic (130, 135 and 140 mmHg) and diastolic (80, 85 and 90 mmHg) BP.

RESULTS

A single automated office BP (AOBP) assessment provides superior predictive values and overall accuracy compared to three manual office BP assessments. For systolic BP, the predictive values are ≤69% for any of the cut-points while the positive predictive values for the single automated measurement is between 80.0% and 86.9% and the overall accuracy gets as high as 74% for the 130 mmHg cut-point. For diastolic BP, the automated readings are also more predictive but in this case, it is the negative predictive values that are better, as well as the overall accuracy.

CONCLUSIONS

Based on the results, we suggest that 135/85 mmHg continue to be used as the cut-point defining high BP with the BpTRU device. However, future research might suggests that values in a grey zone between 130-139 mmHg systolic and 80-89 mmHg diastolic be confirmed using ambulatory BP monitoring. As well, three AOBP assessments might produce much greater accuracy than the single AOBP assessment used in the study.

The method of distance measurement and torso length influences the relationship of pulse wave velocity to cardiovascular mortality

BACKGROUND

The method of estimating distance traveled by the pulse wave, used in the calculation of pulse wave velocity (PWV), is not standardized. Our objective was to assess whether different methods of distance measurement influenced the association of PWV to cardiovascular mortality in hemodialysis (HD) patients.

METHODS

Ninety-eight chronic HD patients had their PWV measured using three methods for distance estimation; PWV1: suprasternal notch-to-femoral site minus suprasternal notch-to-carotid site, PWV2: carotid-to-femoral site, PWV3: carotid-to-femoral site minus suprasternal notch-to-carotid site. Carotid-to-femoral distance was used to approximate torso length. Patients were followed for a median of 30 months and the association of PWV and cardiovascular mortality was assessed using survival analysis before and after stratification for torso length.

RESULTS

The three methods resulted in significantly different PWV values. During follow-up 50 patients died, 32 of cardiovascular causes. In log-rank tests, only tertiles of PWV1 was significantly related to outcome (P values 0.017, 0.257, 0.137, for PWV1, PWV2, and PWV3, respectively). In adjusted Cox, proportional hazards regression only PWV1 was related to cardiovascular mortality. In stratified analysis, however, among patients with below median torso length all PWV values were related to outcome, whereas in patients with above median torso length none of the PWV methods resulted in significant relationship to outcome.

CONCLUSIONS

PWV calculated using suprasternal notch-to-femoral distance minus suprasternal notch-to-carotid distance provides the strongest relationship to cardiovascular mortality. Longer torso weakens the predictive value of PWV, possibly due to more tortuosity of the aorta hence, more error introduced when using surface tape measurements.

Concordance between automatic and manual recording of blood pressure depending on the absence or presence of atrial fibrillation

BACKGROUND

The aim of this study was to determine the concordance between two instruments for measuring blood pressure (BP) and its modification due to the presence or absence of atrial fibrillation (AF).

METHODS

In 107 patients with AF and a sinus rhythm (SR) of 100, BP was recorded using two sphygmomanometers: one automatic and the other manual. Four readings were made with each at 5-min intervals, and the mean was calculated for the statistical calculations. The correlation was determined using Pearson's correlation coefficient, and the concordance using the Bland-Altman plot and the κ index.

RESULTS

The correlation coefficients (r) for the systolic (SBP) and diastolic BP (DBP) were 0.92 and 0.76. If the patient had AF, these were 0.91 and 0.75, respectively. The difference between the automatic and manual SBP measurements depending on whether the patient presented AF was -0.21 and -1.03 mm Hg. In DBP, this was -4.61 and 0.44 mm Hg. This discordance is not modified for low or high BP values, both in patients with AF and those without it. If we classify the patients as hypertensive or not (≥140/90 mm Hg), the concordance between both methods has high κ indices (0.72 and 0.89) both in AF and SR.

CONCLUSION

There is a high correlation between both measurements, which decreased slightly in patients with AF. The difference when comparing the means is clinically irrelevant, and there is a substantial level of concordance between the two measurements for classifying patients as hypertensive or not.

The 2010 Canadian Hypertension Education Program recommendations for the management of hypertension: part I - blood pressure measurement, diagnosis and assessment of risk

OBJECTIVE

To provide updated, evidence-based recommendations for the diagnosis and assessment of adults with hypertension.

EVIDENCE

MEDLINE searches were conducted from November 2008 to October 2009 with the aid of a medical librarian. Reference lists were scanned, experts were contacted, and the personal files of authors and subgroup members were used to identify additional studies. Content and methodological experts assessed studies using prespecified, standardized evidence-based algorithms. Recommendations were based on evidence from peer-reviewed full-text articles only.

RECOMMENDATIONS

Recommendations for blood pressure measurement, criteria for hypertension diagnosis and follow-up, assessment of global cardiovascular risk, diagnostic testing, diagnosis of renovascular and endocrine causes of hypertension, home and ambulatory monitoring, and the use of echocardiography in hypertensive individuals are outlined. Changes to the recommendations for 2010 relate to automated office blood pressure measurements. Automated office blood pressure measurements can be used in the assessment of office blood pressure. When used under proper conditions, an automated office systolic blood pressure of 135 mmHg or higher or diastolic blood pressure of 85 mmHg or higher should be considered analogous to a mean awake ambulatory systolic blood pressure of 135 mmHg or higher and diastolic blood pressure of 85 mmHg or higher, respectively.

VALIDATION

All recommendations were graded according to strength of the evidence and voted on by the 63 members of the Canadian Hypertension Education Program Evidence-Based Recommendations Task Force. To be approved, all recommendations were required to be supported by at least 70% of task force members. These guidelines will continue to be updated annually.

Evaluation scale to assess the accuracy of cuff-less blood pressure measuring devices

OBJECTIVE

The call for early detection of hypertension and cardiac events creates a heavy demand for devices that can be used for blood pressure (BP) monitoring at home and in ambulatory settings. An emerging type of BP monitors without an occluding cuff has drawn great attentions for this application because it is comfortable and capable of providing continuous readings. For the development the cuff-less devices, it is crucial for the clinicians and engineers to joint efforts in establishing an evaluation standard.

METHODS

This study attempts to contribute to its initiation in two ways. First, a new distribution model for measurement differences between the test device and the reference was proposed. We verified the model using evaluation results from 40 devices, of which 80% of the American Association for the Advancement of Medical Instrumentation and British Hypertension Society reporting results were in agreement, as compared with 50%, if the original normal model was used. We further tested a cuff-less device on 85 patients for 999 datasets and found that the differences between the proposed distribution and that of the device were nonsignificant for systolic BP measurements (Kolmogorov-Smirnov = 0.036, P = 0.15). Second, some evaluation scales were studied for their capability to assess the accuracy of cuff-less devices. For mean absolute difference, a map was developed to relate it with the criteria of American Association for the Advancement of Medical Instrumentation, British Hypertension Society, and European Society of Hypertension protocols, on the basis of the proposed distribution model; for mean absolute percentage difference, it is prominent in evaluating devices that have measurement errors often increasing with BP, which is an issue has not been fully explored in existing standards.

CONCLUSION

This study focused on the statistical aspect of establishing standard to assess the accuracy of cuff-less BP measuring devices. The results of our study on the validation reports of various cuff-based devices and an experimental study on a cuff-less device showed that the t4 distribution is better than the normal distribution in portraying the underlying error distribution of both kinds of devices. Moreover, based on both the theoretical and experimental studies, mean absolute difference or mean absolute percentage difference is recommended as continuous scale to assess the accuracy of cuff-less devices for their own distinctive advantages.

Agency social workers could monitor hypertension in the community

Uncontrolled hypertension is highly prevalent, presents without symptoms, and constitutes a major risk factor for atherosclerosis, heart disease, stroke, and diabetes. Several factors impede individuals from adhering to treatment, while others work against physician monitoring and medication adjustment as the condition changes. As family counselors and leaders of self-help and mutual aid groups, social workers are among the best positioned professionals to help individuals, couples, and families improve psychosocial dynamics associated with hypertension, secure support, and overcome barriers to lifestyle changes or medication adherence. An important case is made for training social workers from community social service agencies to engage and guide their clients in accurate self-screenings for hypertension and to refer those with elevated blood pressure for follow-up care.

Comparison of two automated sphygmomanometers for use in the office setting

OBJECTIVE

To compare readings obtained using two automated blood pressure (BP) recording devices, BpTRU and Omron 907, in a clinical setting.

METHODS

Two series of 50 patients attending a hypertension unit for 24-h ambulatory BP monitoring had BP recorded either every 1 or every 2 min using BpTRU and Omron 907 devices with the order of the measurements being randomized.

RESULTS

No significant differences for systolic BP between the mean readings taken using the BpTRU or Omron 907 recorders at either 1 or 2 min were observed. Diastolic BP readings were similar using the 1-min interval setting but were 5.0 mmHg lower for the Omron 907 (P<0.001) when readings were taken at 2-min intervals.

CONCLUSION

BP measurements can be made in the clinical setting using either the BpTRU or Omron 907 automated sphygmomanometers.

Provider communication effects medication adherence in hypertensive African Americans

OBJECTIVE

To evaluate the effect of patients' perceptions of providers' communication on medication adherence in hypertensive African Americans.

METHODS

Cross-sectional study of 439 patients with poorly controlled hypertension followed in community-based healthcare practices in the New York metropolitan area. Patients' rating of their providers' communication was assessed with a perceived communication style questionnaire,while medication adherence was assessed with the Morisky self-report measure.

RESULTS

Majority of participants were female, low-income, and had high school level educations, with mean age of 58 years. Fifty-five percent reported being nonadherent with their medications; and 51% rated their provider's communication to be non-collaborative. In multivariate analysis adjusted for patient demographics and covariates (depressive symptoms, provider degree), communication rated as collaborative was associated with better medication adherence (beta=-.11, p=.03). Other significant correlates of medication adherence independent of perceived communication were age (beta=.13, p=.02) and depressive symptoms (beta=-.18, p=.001).

CONCLUSION

Provider communication rated as more collaborative was associated with better adherence to antihypertensive medications in a sample of low-income hypertensive African-American patients.

PRACTICE IMPLICATIONS

The quality of patient-provider communication is a potentially modifiable element of the medical relationship that may affect health outcomes in this high-risk patient population.

Optimum frequency of office blood pressure measurement using an automated sphygmomanometer

OBJECTIVE

To determine the optimum interval between serial blood pressure measurements using an automated BpTRU sphygmomanometer.

METHODS

Two groups of 200 patients each had automated office measurements taken using the BpTRU device at either 1-min or 2-min intervals from the start of one reading to the start of the next reading with a 24-h ambulatory blood pressure (ABP) recording being performed. Another series of 50 patients had BpTRU readings taken at 1-min and 2-min intervals before and after 24-h ABP monitoring. The difference between the mean awake ABP and the mean automated office BP readings were compared for recordings taken at 1-min versus 2-min intervals.

RESULTS

In the between-patient comparison (n=400), mean awake ABP was similar to automated BP recordings in the examining room at either 1-min or 2-min intervals except for a slightly lower (-4 mmHg) diastolic BP with the 1-min interval (P<0.01 vs. ABP). In the within-patient comparison (n=50), there was no consistent difference between automated BP readings taken in the examining room at 1-min versus 2-min intervals. Overall, the mean automated BP values tended to be slightly lower than the mean awake ABP.

CONCLUSION

Automated measurement of BP in the office setting with devices such as the BpTRU can be taken as frequently as every 1 min without affecting the accuracy of the reading. Small differences in BP between the 1 and 2-min settings and between the automated BpTRU and ABP readings were within accepted clinical standards for validation criteria.

Recent advances in automated blood pressure measurement

During the past 15 years, clinical outcome studies have consistently reported that home and 24-hour ambulatory blood pressure recordings provide a significantly better measure of cardiovascular risk than do manual blood pressure readings taken in the office or clinic. The advent of automated sphygmomanometers that record blood pressure with the patient alone in the examining room will be the next major change in our approach to recording blood pressure. These automated devices virtually eliminate the white coat response and their readings correlate significantly better with the ambulatory blood pressure compared with manual office blood pressure readings. The principal finding from recent research into automated blood pressure measurement is that the presence of an observer during the actual reading in itself provokes the white coat response.

Antihypertensive medication use and blood pressure control: a community-based cross-sectional survey (ON-BP)

BACKGROUND

The Ontario Blood Pressure (ON-BP) survey reported high treatment and control rates for hypertension in the province of Ontario, Canada, in a survey performed in 2006. This study examined patterns of utilization of antihypertensive drug classes and their impact on blood pressure (BP) control.

METHODS

Cross-sectional, population-based survey of adults, 20-79 years of age (population 7,996,653). Responses are weighted to the Ontario hypertensive population of 1,498,045.

RESULTS

Of all hypertensives, 51 and 49% were on monotherapy vs. 2+ drug therapy with similar control rates (86 vs. 80%, respectively). In those on monotherapy a renin-angiotensin system (RAS) blocker was the most commonly used drug class (62%) and use of other drug classes was only approximately 10%. In those on 2+ therapy, a RAS blocker was also the most common class (80%), followed by a diuretic (67%). In diabetics with hypertension 46 and 54% were on monotherapy vs. 2+ drug therapy with significantly higher control rates on monotherapy (90 vs. 46%). RAS blocker was also the most common drug class (85 and 80%, respectively), but in those on 2+ drugs only 45% were on a diuretic. Control rates did not differ by type of drug treatment in the overall hypertensive population and those with a comorbidity, but were low in diabetics on 2+ therapy and particularly in those on a calcium channel blocker (CCB) or diuretic.

CONCLUSIONS

High treatment and control rates of hypertension in Ontario are associated with high utilization of RAS blockers. Diabetics on 2+ therapy are the least effectively controlled, possibly reflecting the limited use of diuretics.

Enhancing hypertension awareness and management in the elderly: lessons learned from the Airdrie Community Hypertension Awareness and Management Program (A-CHAMP)

BACKGROUND

High blood pressure (BP) is an established and modifiable cardiovascular risk factor; however, awareness and management of this primarily asymptomatic disease remains suboptimal.

OBJECTIVES

The Airdrie Community Hypertension Awareness and Management Program (A-CHAMP) was a community-based BP program for seniors designed to improve public and health care provider awareness and management of hypertension.

METHODS

Volunteer peer health educators (VPHEs) were recruited from the community and trained to manage BP screening sessions in local pharmacies. Airdrie (Alberta) residents 65 years of age and older were invited by their family physicians (FPs) to attend the A-CHAMP sessions. VPHEs identified participants' cardiovascular risk factors, assessed BP with a validated automated device and implemented a management algorithm. Participants with BP higher than 159/99 mmHg were directed to their pharmacists and FPs. All participants with elevated BP at the initial A-CHAMP session were invited to return to a follow-up session four to six months later.

RESULTS

Thirty VPHEs were recruited and trained. All 15 FPs and all six pharmacies in Airdrie participated. VPHEs assessed 406 seniors (approximately 40% of Airdrie seniors) during the three-month program. One hundred forty-eight participants (36.5%) had elevated BP at their first session. Of these, 71% returned for the follow-up session four to six months later. The mean (+/- SD) systolic BP decreased by 16.9+/-17.2 mmHg (P<0.05, n=105) compared with their first visit, and 56% of participants (59 of 105) reached Canadian targets for BP.

CONCLUSIONS

A-CHAMP raised awareness, and identified and managed seniors with hypertension. At follow-up, BP showed statistically and clinically significant and sustained improvement. Participating health care providers and VPHEs indicated that A-CHAMP was effective and feasible in improving awareness and control of hypertension.

Results of the Ontario survey on the prevalence and control of hypertension

BACKGROUND

Available information on the prevalence and management of hypertension in the Canadian population dates back to 1986-1992 and probably does not reflect the current status of this major risk factor for cardiovascular disease. We sought to evaluate the current prevalence and management of hypertension among adults in the province of Ontario.

METHODS

Potential respondents from randomly selected dwellings within target neighbourhoods in 16 municipalities were contacted at their homes to request participation in the study. For potential respondents who agreed to participate, blood pressure was measured with an automated device. Estimation weights were used to obtain representative estimates of population parameters. Responses were weighted to the total adult population in Ontario of 7,996,653.

RESULTS

From 6436 eligible dwellings, contact was made with 4559 potential participants, of whom 2992 agreed to participate. Blood pressure measurements were obtained for 2551 of these respondents (age 20-79 years). Hypertension, defined as systolic blood pressure of 140 mm Hg or more, diastolic blood pressure of 90 mm Hg or more, or treatment with an antihypertensive medication, was identified in 21.3% of the population overall (23.8% of men and 19.0% of women). Prevalence increased with age, from 3.4% among participants 20-39 years of age to 51.6% among those 60-79 years of age. Hypertension was more common among black people and people of South Asian background than among white people; hypertension was also associated with higher body mass index. Among participants with hypertension, 65.7% were undergoing treatment with control of hypertension, 14.7% were undergoing treatment but the hypertension was not controlled, and 19.5% were not receiving any treatment (including 13.7% who were unaware of their hypertension). The extent of control of hypertension did not differ significantly by age, sex, ethnic background or comorbidities.

INTERPRETATION

In Ontario, the overall prevalence of hypertension is high in the older population but appears not to have increased in recent decades. Hypertension management has improved markedly among all age groups and for both sexes.

Comparison between an automated and manual sphygmomanometer in a population survey

BACKGROUND

An automated sphygmomanometer, the BpTRU, was used in a blood pressure (BP) survey of 2,551 residents in the province of Ontario. Automated BP readings were compared with measurements taken by a mercury sphygmomanometer under standardized conditions in a random 10% sample.

METHODS

BP was recorded in 238 individuals in random order using both a standard mercury device and an automated BP recorder, the BpTRU. All subjects rested for 5 min prior to the first BP reading, which was then discarded. The mean of the next three readings was obtained using the mercury device whereas the BpTRU was set to record a mean of five readings taken at 1 min intervals with subjects resting alone in a quiet room.

RESULTS

The mean s.d. BP with the automated device was 115 +/- 16/71 +/- 10 mm Hg compared to 118 +/- 16/74 +/- 10 mm Hg for the manual BP (P < 0.001). A systolic BP > or = 140 mm Hg was present for 16 automated and 19 manual readings. Similarly, the diastolic BP was > or = 90 mm Hg for 9 automated and 14 manual readings. Linear regression analysis showed that automated BP was a significant (P < 0.001) predictor of both manual systolic and diastolic BP.

CONCLUSION

Conventional manual BP readings can be replaced by readings taken using a validated, automated BP recorder in population surveys. The slightly lower readings obtained with the BpTRU device (in the context of reduced observer-subject interaction) may be a more accurate estimate of BP status.

Performance of the automated BpTRU measurement device in the assessment of white-coat hypertension and white-coat effect

OBJECTIVES

BpTRU (VSM MedTech Ltd, Vancouver, Canada) is an automated oscillometric device that provides serial blood pressure measurements in an office setting in the absence of a healthcare professional. We sought to determine whether the white-coat effect is reduced by a blood pressure measurement protocol using BpTRU compared with casual office measurements. Secondarily, we also sought to determine whether a blood pressure measurement protocol using BpTRU reduced white-coat hypertension compared with the casual office measurements, and reduced white-coat effect and white-coat hypertension compared with blood pressure obtained by a research nurse.

METHODS

Blood pressure was measured in 107 adult hypertensive patients referred for ambulatory blood pressure monitoring using an ambulatory blood pressure monitor, a standardized protocol by a trained research nurse, and a protocol using BpTRU (five readings over 25 min, using the 5-min blood pressure measurement interval setting). Casual office blood pressure was also recorded in the family physicians' offices. Using the mean daytime ambulatory blood pressure as the reference standard, the proportion of patients with white-coat effect and white-coat hypertension were determined for measurements obtained by BpTRU, the research nurse, and the family physicians' offices.

RESULTS

Casual office blood pressure measurements demonstrated a white-coat effect in 39 (36.4%) patients; seven (6.5%) patients demonstrated a white-coat effect using BpTRU (P<0.0001). White-coat hypertension was also less common using BpTRU than with the casual office readings (13 vs. 1 patient, P<0.0001). White-coat effect was also reduced with BpTRU compared with the research nurse measurements. Unfortunately, percentage agreement for the diagnosis of hypertension between the protocol using BpTRU and the reference standard was only 48%. This resulted in substantial misclassification of hypertension by the BpTRU measurement protocol.

CONCLUSIONS

Although BpTRU reduces white-coat effect and white-coat hypertension, blood pressure is underestimated by the device, leading to misclassification of hypertension. BpTRU, when set at 5-min blood pressure measurement intervals, should not be used in clinical practice.

A community-based program for cardiovascular health awareness

OBJECTIVE

The objective of the Cardiovascular Health Awareness Program (CHAP) is to improve the processes of care related to the cardiovascular health of older adults.

PARTICIPANTS

Two Ontario communities including family physicians (FP), pharmacists, public health units and nurses, volunteer peer health educators, older adult patients and community organizations.

SETTING

Community pharmacies and family physician offices.

INTERVENTION

CHAP is designed to close a process of care loop around cardiovascular health awareness that originates from, and returns to, the FP. Older patients are invited by their FP to attend pharmacy CHAP sessions. At these sessions, trained volunteer peer health educators (PHEs) assist patients both in recording their blood pressure using a calibrated automated device and in completing a cardiovascular risk profile. This information is relayed to their respective FP via an automated computerized database. Pharmacists and patients receive copies of the results. Based on these cumulative risk profiles, patients are advised to follow-up with their FP.

OUTCOMES

Of the FPs and pharmacists asked, 47% and 79%, respectively, agreed to participate in the project. 39% of older adult patients invited by their FPs attended the CHAP community pharmacy sessions. Of these, 100% agreed to having their risk profile, including their blood pressure readings, forwarded to their FP. Positive feedback about CHAP was expressed by the volunteer PHEs, the FPs and the pharmacists.

CONCLUSION

The community-based pharmacy CHAP sessions are a feasible way of improving patient, physician, and pharmacist access to reliable blood pressure measurements and to cardiovascular health information. A randomized trial is in progress that will assess the impact of CHAP on monitoring of blood pressure.

Automated assessment of blood pressure using BpTRU compared with assessments by a trained technician and a clinic nurse

OBJECTIVE

To determine the accuracy and reproducibility of a new automated blood pressure manometer (BpTRU) relative to auscultatory blood pressure assessed by a research nurse and to that assessed by a clinic nurse.

METHODS

Firefighters in a cohort study had blood pressure assessed on up to five occasions with BpTRU and by a trained research technician. Patients in an internal medicine clinic had blood pressure assessed by the clinic nurse and by BpTRU. The absolute values of blood pressure, reproducibility and effect on hypertension classification were compared with the different methods.

RESULTS

The research technician readings were higher than the BpTRU readings at visit 1 (3.0/2.7 mmHg, P<0.0001) but the readings converged by visits 4-5 because of a greater reduction in the research nurse readings. The BpTRU readings had similar reproducibility and classification of hypertension as the research technician but did not exhibit terminal digit preference while the research technician readings did. The BpTRU had substantially lower readings (8/7 mmHg) and fewer hypertensive readings than those of the nurse in the internal medicine clinic.

CONCLUSIONS

This preliminary study found that the BpTRU had desirable characteristics that suggest that it would be a suitable replacement for auscultatory assessment of blood pressure in clinical practice. A large confirmatory study performed in a usual clinic setting is required.

Is the accuracy of blood pressure measuring devices underestimated at increasing blood pressure levels?

BACKGROUND

In validation studies reporting on the accuracy of blood pressure measuring devices (ambulatory and non-ambulatory systems), it is frequently stated that the accuracy of blood pressure devices seems to decrease at increasing blood pressure levels. This has been shown for several ambulatory devices in the past. Whether more recently validated devices are less accurate at increasing blood pressure levels is unknown, however.

OBJECTIVES

We therefore retrospectively searched the literature for studies performed between 1993 and 2003, reporting on the accuracy of blood pressure measuring devices over different blood pressure levels. When needed, additional information from the authors was requested.

METHODS

In total, 30 studies were selected. Of these, the studies reporting on the accuracy of 14 different ambulatory and nine different non-ambulatory devices were useful. For both ambulatory and non-ambulatory devices, accuracy appeared to decrease at increasing blood pressure levels. This was particularly shown for systolic blood pressure.

RESULTS

We speculate whether this finding is due to the oscillometric method of blood pressure measurement. Another explanation may exist, however. Blood pressure variability increases with higher blood pressure. Further, the British Hypertension Society protocol 1993 uses sequential measurements. This may be the reason that, owing to the increased blood pressure variability, the accuracy of most devices tends to decrease at higher blood pressure levels. Consequently, the accuracy of blood pressure measuring devices may be underestimated at higher blood pressure levels.

CONCLUSION

Currently used automated blood pressure measurement devices seem to be less accurate at increasing blood pressure levels. It is important to be aware of this phenomenon when treating hypertensive patients. The reported decrease in accuracy, however, may well be explained by the increasing blood pressure variability at increasing blood pressure and the use of sequential measurements. If this is the case, then the accuracy of these devices is perhaps underestimated.

A randomized trial of mail vs. telephone invitation to a community-based cardiovascular health awareness program for older family practice patients [ISRCTN61739603]

Background

Family physicians can play an important role in encouraging patients to participate in community-based health promotion initiatives designed to supplement and enhance their in-office care. Our objectives were to determine effective approaches to invite older family practice patients to attend cardiovascular health awareness sessions in community pharmacies, and to assess the feasibility and acceptability of a program incorporating invitation by physicians and feedback to physicians.

Methods

We conducted a prospective randomized trial with 1 family physician practice and 5 community pharmacies in Dundas, Ontario. Regular patients 65 years or older (n = 235) were randomly allocated to invitation by mail or telephone to attend pharmacy cardiovascular health awareness sessions led by volunteer peer health educators. A health record review captured blood pressure status, monitoring and control. At the sessions, volunteers helped patients to measure blood pressure using in-store machines and a validated portable device (BPM-100), and recorded blood pressure readings and self-reported cardiovascular risk factors. We compared attendance rates in the mail and telephone invitation groups and explored factors potentially associated with attendance.

Results

The 119 patients invited by mail and 116 patients contacted by telephone had a mean age of 75.7 (SD, 6.4) years and 46.8% were male. Overall, 58.3% (137/235) of invitees attended a pharmacy cardiovascular health awareness session. Patients invited by telephone were more likely to attend than those invited by mail (72.3% vs. 44.0%, OR 3.3; 95%CI 1.9–5.7; p < 0.001).

Conclusion

While the attendance in response to a telephone invitation was higher, response to a single letter was substantial. Attendance rates indicated considerable interest in community-based cardiovascular health promotion activities. A large-scale trial of a pharmacy cardiovascular health awareness program for older primary care patients is feasible.

The BpTRU automatic blood pressure monitor compared to 24 hour ambulatory blood pressure monitoring in the assessment of blood pressure in patients with hypertension

BACKGROUND

Increasing evidence suggests that ABPM more closely predicts target organ damage than does clinic measurement. Future guidelines may suggest ABPM as routine in the diagnosis and monitoring of hypertension. This would create difficulties as this test is expensive and often difficult to obtain. The purpose of this study is to determine the degree to which the BpTRU automatic blood pressure monitor predicts results on 24 hour ambulatory blood pressure monitoring (ABPM).

METHODS

A quantitative analysis comparing blood pressure measured by the BpTRU device with the mean daytime blood pressure on 24 hour ABPM. The study was conducted by the Centre for Studies in Primary Care, Queen's University, Kingston, Ontario, Canada on adult primary care patients who are enrolled in two randomized controlled trials on hypertension. The main outcomes were the mean of the blood pressures measured at the three most recent office visits, the initial measurement on the BpTRU-100, the mean of the five measurements on the BpTRU monitor, and the daytime average on 24 hour ABPM.

RESULTS

The group mean of the three charted clinic measured blood pressures (150.8 (SD10.26) / 82.9 (SD 8.44)) was not statistically different from the group mean of the initial reading on BpTRU (150.0 (SD21.33) / 83.3 (SD12.00)). The group mean of the average of five BpTRU readings (140.0 (SD17.71) / 79.8 (SD 10.46)) was not statistically different from the 24 hour daytime mean on ABPM (141.5 (SD 13.25) / 79.7 (SD 7.79)). Within patients, BpTRU average correlated significantly better with daytime ambulatory pressure than did clinic averages (BpTRU r = 0.571, clinic r = 0.145). Based on assessment of sensitivity and specificity at different cut-points, it is suggested that the initial treatment target using the BpTRU be set at <135/85 mmHG, but achievement of target should be confirmed using 24 hour ABPM.

CONCLUSION

The BpTRU average better predicts ABPM than does the average of the blood pressures recorded on the patient chart from the three most recent visits. The BpTRU automatic clinic blood pressure monitor should be used as an adjunct to ABPM to effectively diagnose and monitor hypertension.

Overall accuracy of the BpTRU--an automated electronic blood pressure device

BACKGROUND

The objective of this report is to combine the data from an earlier adult study with the data from a paediatric study in order to determine the overall accuracy of the BpTRU (BPM-100 model) as compared to the recognized standard, auscultatory mercury sphygmomanometer.

DESIGN

The individual blood pressure points recorded for both adult and paediatric studies were compared directly to its corresponding observer reference measurements from data collected and stored from the two separate studies. There were 255 sets of readings in the adult study and 162 sets from the paediatric study, which were combined to make 417 pairs of blood pressure readings for this study.

METHODS

The overall observer standard reference mean for the 417 measurements was calculated and the difference between this and the overall mean BPM-100 was calculated with SD and ranges. Measurements within 5, 10 and 15 mmHg agreement were expressed as percentages.

RESULTS

A total of 121 subjects were included for this study (85 from the adult study and 36 from the paediatric study). From these, 417 paired measurements were recorded. The mean difference between the BpTRU and the reference standard systolic blood pressure (BP) was 0.47+/-5.40 mmHg with 89.2% measurements within 5 mmHg, 96.4% within 10 mmHg and 99.3% within 15 mmHg. The mean difference between the BpTRU and reference diastolic BP was -2.12+/-5.93 mmHg with 81.1% within 5 mmHg, 92.1% within 10 mmHg and 97.6% within 15 mmHg.

CONCLUSION

The BpTRU has been shown to be an accurate non-invasive blood pressure monitoring device in the general population over a wide range of ages (3-83 years). This combined study meets all requirements of the Association of Advancement of Medical Instrumentation and achieved a grade 'A' in the BHS protocol.

Comparison of the automated non-invasive oscillometric blood pressure monitor (BpTRU) with the auscultatory mercury sphygmomanometer in a paediatric population

BACKGROUND

To directly compare the accuracy of the BpTRU (an automated oscillometric blood pressure device) with standard auscultatory mercury sphygmomanometry in a pediatric population.

DESIGN

The BpTRU was connected in parallel with a standard mercury sphygmomanometer. Two observers measured the blood pressures at the same time as it was being measured by the BpTRU. The observers and the BpTRU were all blinded from each other.

METHODS

For each of the demographic data--subject age, sex and arm sizes--the mean, standard deviation (SD) and range was calculated. The difference between the mean BpTRU and the standard reference measurements (observer average) was calculated with SD and ranges. The percentage of measurements within 5, 10 and 15 mmHg agreement was expressed.

RESULTS

From the 36 subjects recruited aged 3-18 years, 162 pairs of sitting blood pressures were included. The difference between the mean BpTRU readings and the reference standard measurements (as determined by the observers) was 1.45+/-5.67 mmHg for systolic blood pressures, and -3.24+/-7.39 mmHg for diastolic pressure and 0.20+/-2.47 bpm for heart rate.

CONCLUSION

The BpTRU is of similar accuracy in measuring blood pressure in children as it was in an adult population.

The profile of cardiac patients with renal artery stenosis

OBJECTIVES

We examined the prevalence and severity of renal artery stenosis (RAS) in patients undergoing cardiac catheterization who were deemed at risk for RAS based on clinical or laboratory criteria for study entry, but who had not previously been suspected of having RAS.

BACKGROUND

The diagnosis of atherosclerotic RAS remains problematic because its clinical manifestations are nonspecific.

METHODS

Consecutive patients undergoing non-emergent cardiac catheterization at a single institution during a 12-month period were evaluated using standardized clinical, laboratory, and angiographic criteria. Patients exhibiting at least one of four predefined selection criteria (severe hypertension, unexplained renal dysfunction, acute pulmonary edema with hypertension, or severe atherosclerosis) were prospectively registered and underwent coincident diagnostic renal angiography.

RESULTS

Renal angiography was performed in 851 patients and was diagnostic in 837. Angiographically evident renal atherosclerosis was present in 39% of the population, with RAS > or =50% in 120 (14.3%) and severe stenosis (> or =70%) in 61 (7.3%). Severe stenosis was present in 48 (7%) patients with severe atherosclerosis, 38 (16%) with renal dysfunction, 25 (9%) with hypertension, and 2 (22%) with acute pulmonary edema with hypertension. The prevalence was higher in those exhibiting multiple selection criteria. In a multivariate model, severe RAS was associated with age, female gender, reduced creatinine clearance, increased systolic blood pressure, and peripheral or carotid artery disease.

CONCLUSIONS

In a population at risk of, but not previously suspected of having RAS, severe RAS is associated with simple and readily determined clinical and laboratory patient characteristics. These data facilitate focused application of diagnostic renal angiography.

Hypertension screening in a salami factory: a worksite hypertension study

The prevalence, awareness and control of hypertension are important epidemiological research topics worldwide. The screening of hypertension in a workplace has some special aspects. We have screened the employees in a Hungarian salami factory (Pick Salami Factory, Szeged, Hungary) for hypertensives. In a cross-sectional survey, the blood pressure (BP) was measured with an instrument meeting accepted measuring principles (BP-TRU BP) and a questionnaire was filled. In all, 1012 factory workers were screened (600 male and 412 female) and 25.7% of the workers proved to be hypertensives. Of these, 61.5% of the hypertensive employees were aware that their BP is high. Among the treated hypertensives, 21.9% were controlled. These results suggest that the efficacy of the management of hypertension in Hungary cannot be solely responsible for the high cardiovascular morbidity and mortality. The improvement of the management of hypertension should decrease the cardiovascular risk in the hypertensive population. The worksite screening and follow-up of hypertension seem to be logical health service solutions. This has been proven to be cost-effective.

Work-site hypertension prevalence and control in three Central European Countries

Compared to Austria, cerebrovascular stroke (CVS) mortality is three times higher in Hungary, and twice as high in Slovakia. We hypothesized that this is due to better treatment and control of hypertension in Austria. To test this hypothesis, we carried out a cross-sectional survey of 'blue collar' employees on work sites in each of these countries. Blood pressure screening was carried out at three work sites in Austria, one in Hungary and one in Slovakia. A standardized protocol was followed in each of these countries. The Bp-TRU(TM) measuring instrument was used to provide accurate reproducible readings and eliminate interobserver error. After the exclusion of missing data and women, the study population included 323 males screened in Austria, 600 in Hungary, and 751 in Slovakia. The mean ages of the respondents ranged from 35 to 42 years. The prevalence of hypertension was 29% in Austria, 28% in Hungary and 40% in Slovakia. Of those identified as hypertensive, 73% in Austria, 45% in Hungary and 67% in Slovakia were newly diagnosed as a result of this screening. Of those treated for hypertension, 10% in Austria, 15% in Hungary and 5% in Slovakia were controlled. The differences in CVS mortality cannot be explained by better control of hypertension in Austria but indicate the involvement of other determinants.

What will replace the mercury sphygmomanometer?

Mercury sphygmomanometers are gradually being phased out, not because of any technological advances but because of environmental concerns. While mercury is still accepted as the 'gold standard' for routine clinical measurement, it suffers from two deficiencies: poor observer technique, and problems due to poor maintenance of the devices. At the same time, there is no generally accepted alternative; the most widely advocated candidates are aneroid or oscillometric devices. Oscillometric devices have the advantages of eliminating observer error and mechanical drift, but it is suggested that the inherent limitations of the oscillometric method mean that it cannot become the gold standard for clinical measurement in individual patients. Aneroid monitors have been found in practice to be frequently deficient, and are subject to the same deficiencies in observer technique as mercury devices. Two possible but so far untested techniques are a 'hybrid' sphygmomanometer, whereby the mercury column is replaced by an electronic transducer and display, and the wideband recording technique, which has the potential of using the same basic principle as the auscultatory technique, while eliminating the human observer.

Comparison of the oscillometric blood pressure monitor (BPM-100(Beta) ) with the auscultatory mercury sphygmomanometer

BACKGROUND

To compare directly the accuracy of the BPM-100(Beta) monitor (an automated oscillometric blood pressure device) with standard auscultatory mercury sphygmomanometry.

DESIGN

The BPM-100(Beta) was connected in parallel via a T-tube to a mercury sphygmomanometer. The BPM-100(Beta) and two trained observers (blinded from each other and from the BPM-100(Beta)) measured the sitting blood pressure simultaneously.

METHODS

Means, standard deviations and ranges were calculated for all the demographic data: age, arm size, heart rate and blood pressure. The agreement between the BPM-100(Beta) and the mean of two observers (the reference) was determined and expressed as the mean +/- SD, as well as the percentage of differences falling within 5, 10 and 15 mmHg.

RESULTS

Of the 92 subjects recruited, 85 (92.4%) met the inclusion criteria, and 391 sets of sitting blood pressure and heart rate measurements were available for analysis. The mean difference between the BPM-100(Beta) monitor and the reference was -0.62 +/- 6.96 mmHg for systolic blood pressure, -1.48 +/- 4.80 mmHg for diastolic blood pressure and 0.14 +/- 1.86 beats/min for heart rate. The only limitation of the device was its tendency to underestimate higher systolic blood pressures. This problem has been addressed by a minor change in the algorithm (see the companion publication, Blood Press Monit, 6, 161-165, 2001).

CONCLUSION

The BPM-100(Beta) is an accurate blood pressure monitor for the office setting, meeting all requirements of the Association for the Advancement of Medical Instrumentation and achieving an 'A' grade according to the British Hypertension Society protocol.