The accuracy and precision of the Accutracker ambulatory blood pressure monitor

Neurocognition in treatment-resistant hypertension: profile and associations with cardiovascular biomarkers

BACKGROUND

Hypertension in midlife has been associated with increased risk of stroke and neurocognitive decline. Few studies, however, have examined neurocognition among individuals with treatment-resistant hypertension or potential mechanisms by which treatment-resistant hypertension may impair neurocognition.

METHODS

We examined the pattern of neurocognitive impairment and potential mechanisms in a sample of 96 overweight adults with treatment-resistant hypertension, aged 41-81 years. Neurocognitive function was assessed using a 45-min test battery consisting of executive function and memory. Vascular and metabolic mechanisms examined included cerebrovascular risk factors (CVRFs: Framingham Stroke Risk Profile), insulin sensitivity (homeostatic model assessment of insulin resistance), waist-to-hip ratio, microvascular function (hyperemic response), and peak oxygen consumption from an exercise treadmill test. Simple path analyses were used to assess the association between potential vascular and metabolic mechanisms and neurocognition.

RESULTS

Neurocognitive impairments were common, with 70% of the sample exhibiting impaired performance on at least one executive function subtest and 38% on at least one measure of memory. Higher levels of aerobic fitness, greater insulin sensitivity, and better microvascular function, as well as lower CVRFs and waist-to-hip ratio were associated with better neurocognition. In path analyses, aerobic fitness, microvascular function, and CVRFs all were independently associated with neurocognitive performance. Insulin resistance associated with worse executive function but better memory performance among older participants.

CONCLUSION

Neurocognitive impairments are common in adults with treatment-resistant hypertension, particularly on tests of executive function. Better neurocognition is independently associated with aerobic fitness, microvascular function, and CVRFs.

User experience of instant blood pressure: exploring reasons for the popularity of an inaccurate mobile health app

Instant blood pressure (IBP) is a top-selling yet inaccurate blood pressure (BP)-measuring app that underreports elevated BP. Its iTunes app store user ratings and reviews were generally positive. Whether underreporting of elevated BP improves user experience is unknown. Participants enrolled at five clinics estimated their BP, measured their BP with IBP, then completed a user experience survey. Participants were grouped based on how their IBP BP measurements compared to their estimated BP (IBP Lower, IBP Similar, or IBP Higher). Logistic regressions compared odds of rating "agree" or "strongly agree" on survey questions by group. Most participants enjoyed using the app. In the adjusted model, IBP Higher had significantly lower proportions reporting enjoyment and motivation to check BP in the future than IBP Similar. All three groups were comparable in perceived accuracy of IBP and most participants perceived it to be accurate. However, user enjoyment and likelihood of future BP monitoring were negatively associated with higher-than-expected reported systolic BP. These data suggest reassuring app results from an inaccurate BP-measuring app may have improved user experience, which may have led to more positive user reviews and greater sales. Systematic underreporting of elevated BPs may have been a contributor to the app's success. Further studies are needed to confirm whether falsely reassuring output from other mobile health apps improve user experience and drives uptake.

Effects of exercise and stress management training on nighttime blood pressure dipping in patients with coronary heart disease: A randomized, controlled trial

INTRODUCTION

Blunted nighttime blood pressure (BP) dipping is prognostic of cardiovascular morbidity and mortality. Patients with coronary heart disease (CHD) are often characterized by a blunted nighttime BP dipping pattern. The present study compared the effects of 2 behavioral intervention programs, aerobic exercise (EX) and stress management (SM) training, with a usual care (UC) control group on BP dipping in a sample of CHD patients.

METHODS

This was a secondary analysis of a randomized, controlled trial with allocation concealment and blinded outcome assessment in 134 patients with stable CHD and exercise-induced myocardial ischemia. Nighttime BP dipping was assessed by 24-hour ambulatory BP monitoring, at prerandomization baseline and after 16 weeks of one of the following treatments: usual medical care; UC plus supervised aerobic EX for 35 minutes, 3 times per week; UC plus weekly 1.5-hour sessions of SM training.

RESULTS

The EX and SM groups exhibited greater improvements in systolic BP dipping (P=.052) and diastolic BP dipping (P=.031) compared with UC. Postintervention systolic BP percent-dipping means were 12.9% (SE=1.5) for SM, 11.1% (SE=1.4) for EX, and 8.6% (SE=1.4) for UC. Postintervention diastolic BP percent-dipping means were 13.3% (SE=1.9) for SM, 14.1% (SE=1.8) for EX, and 8.8% (1.8) for UC.

CONCLUSIONS

For patients with stable CHD, EX or SM training resulted in improved nighttime BP dipping compared with usual medical care. These favorable effects of healthy lifestyle modifications may help reduce the risk of adverse clinical events.

Effects of dipping and psychological traits on morning surge in blood pressure in healthy people

Despite the role of anxiety, depression and hostility in the pathogenesis of cardiovascular diseases, their impact on two significant cardiovascular risk factors, nocturnal dipping and morning surge in blood pressure (MSBP), are largely ignored and primarily studied in clinical populations. This study examined the effects of dipping and psychological traits on MSBP in healthy people. Nocturnal dipping and MSBP were derived from 24-h ambulatory BP obtained in 77 men and 79 women, mean age 32.8 (s.d.: 7.4). Differences in depression, anxiety and hostility were examined by questionnaires. Higher levels of dipping (P<0.0001) and depressive symptoms (P=0.01) independently contributed to increased MSBP. Dipping interacts with depression (P=0.04), hostility (P=0.01) and anxiety (P=0.04) in determining MSBP. Low dippers with higher scores on the psychological traits showed higher MSBP than high dippers. A significant MSBP interaction was found between sex and depressive symptoms (P=0.05), anxiety (P<0.0001) and hostility (P=0.01) with higher scores associated with increased MSBP observed in males. Findings underscore depression as a predictor of MSBP independent of dipping. The clinically significant relationship between dipping and non-dipping patters, psychological traits and MSBP requires further investigation.

Definition of ambulatory blood pressure targets for diagnosis and treatment of hypertension in relation to clinic blood pressure: prospective cohort study

BACKGROUND

Twenty-four hour ambulatory blood pressure thresholds have been defined for the diagnosis of mild hypertension but not for its treatment or for other blood pressure thresholds used in the diagnosis of moderate to severe hypertension. We aimed to derive age and sex related ambulatory blood pressure equivalents to clinic blood pressure thresholds for diagnosis and treatment of hypertension.

METHODS

We collated 24 hour ambulatory blood pressure data, recorded with validated devices, from 11 centres across six Australian states (n=8575). We used least product regression to assess the relation between these measurements and clinic blood pressure measured by trained staff and in a smaller cohort by doctors (n=1693).

RESULTS

Mean age of participants was 56 years (SD 15) with mean body mass index 28.9 (5.5) and mean clinic systolic/diastolic blood pressure 142/82 mm Hg (19/12); 4626 (54%) were women. Average clinic measurements by trained staff were 6/3 mm Hg higher than daytime ambulatory blood pressure and 10/5 mm Hg higher than 24 hour blood pressure, but 9/7 mm Hg lower than clinic values measured by doctors. Daytime ambulatory equivalents derived from trained staff clinic measurements were 4/3 mm Hg less than the 140/90 mm Hg clinic threshold (lower limit of grade 1 hypertension), 2/2 mm Hg less than the 130/80 mm Hg threshold (target upper limit for patients with associated conditions), and 1/1 mm Hg less than the 125/75 mm Hg threshold. Equivalents were 1/2 mm Hg lower for women and 3/1 mm Hg lower in older people compared with the combined group.

CONCLUSIONS

Our study provides daytime ambulatory blood pressure thresholds that are slightly lower than equivalent clinic values. Clinic blood pressure measurements taken by doctors were considerably higher than those taken by trained staff and therefore gave inappropriate estimates of ambulatory thresholds. These results provide a framework for the diagnosis and management of hypertension using ambulatory blood pressure values.

Immediate antecedents of cigarette smoking in smokers with and without posttraumatic stress disorder: a preliminary study

Using ambulatory methods for 1 day of monitoring, the authors of this study investigated the association between smoking and situational cues in 63 smokers with posttraumatic stress disorder (PTSD) and 32 smokers without PTSD. Generalized estimating equations contrasted 682 smoking and 444 nonsmoking situations by group status. Smoking was strongly related to craving, positive and negative affect, PTSD symptoms, restlessness, and several situational variables among PTSD smokers. For non-PTSD smokers, the only significant antecedent variables for smoking were craving, drinking coffee, being alone, not being with family, not working, and being around others who were smoking. These results are consistent with previous ambulatory findings regarding mood in smokers but also underscore that, in certain populations, mood and symptom variables may be significantly associated with ad lib smoking.

Effects of amlodipine and fosinopril on heart rate variability and left ventricular mass in mild-to-moderate essential hypertension

The differences between long-acting dihydropyridines and angiotensin-converting enzyme inhibitors with regard to their long-term effects on 24-h heart rate variability (HRV) and left ventricular (LV) mass are less clear in mild-to-moderate essential hypertension. We studied the long-term effects of amlodipine and fosinopril on 24-h HRV and LV mass in mild-to-moderate essential hypertension. In this study, 27 patients with never treated mild-to-moderate essential hypertension were randomised to receive either amlodipine or fosinopril once daily as monotherapy. At baseline and at the end of the third and sixth months, each of the patients underwent 24-h HRV and ambulatory systolic (SBP) and diastolic (DBP) blood pressure analysis. LV mass index was calculated from echocardiographic examination at baseline and at the end of the sixth month. In amlodipine group (n = 14), 24-h SBP/DBP (mmHg) decreased from 144 +/- 8/94 +/- 4 to 128 +/- 6/83 +/- 3 at the end of the third month and to 125 +/- 5/81 +/- 2 at the end of the sixth month (p < 0.0001). In fosinopril group (n = 13), the respective changes were 143 +/- 9/97 +/- 7, 132 +/- 6/87 +/- 5 and 127 +/- 6/82 +/- 3 (p < 0.0001). At the end of the sixth month, LV mass index (g/m(2)) decreased from 122 +/- 26 to 105 +/- 21 in amlodipine group (p < 0.0001) and from 118 +/- 23 to 101 +/- 14 in fosinopril group (p < 0.0001). There were no significant changes in HRV parameters in both the groups. It was concluded that both drugs caused significant decrease in SBP and DBP, and LV mass in patients with mild-to-moderate essential hypertension did not have significant long-term effects of either amlodipine or fosinopril on 24-h HRV parameters reflecting sympathetic or parasympathetic activity in these patients.

Cigarette smoking, ambulatory cardiovascular monitoring, and mood in Vietnam veterans with and without chronic posttraumatic stress disorder

This study investigated the association among cigarette smoking, posttraumatic stress disorder (PTSD), and ambulatory cardiovascular and mood monitoring in 117 male Vietnam combat veterans (61 with PTSD and 56 without PTSD). Positive smoking status was associated with higher systolic blood pressure (SBP) and heart rate (HR), as well as greater diastolic blood pressure (DBP) variability. Compared to individuals without PTSD, PTSD patients had higher HR, anger/hostility ratings, and depression/anxiety ratings. Significant diagnosis by smoking status interactions were found indicating that compared to nonsmokers with PTSD, smokers with PTSD had higher DBP, mean arterial pressure (MAP), and positive affect. Ad lib cigarette smoking during the previous 30 min did not have a significant effect on mood or cardiovascular parameters, except in non-PTSD smokers who reported lower depression/anxiety ratings after smoking. Findings suggest that the effect of smoking on cardiovascular parameters may be amplified in smokers in PTSD. Findings suggest that the interrelationships among cardiovascular parameters, cigarette smoking, and PTSD deserve more research attention.

Ambulatory monitoring and physical health report in Vietnam veterans with and without chronic posttraumatic stress disorder

This study investigated the associations among PTSD, ambulatory cardiovascular monitoring, and physical health self-reports in 117 male Vietnam combat veterans (61 with PTSD and 56 without PTSD). PTSD was associated with health symptoms and number of current health conditions beyond the influence of several covariates. PTSD was associated with greater systolic blood pressure variability, and an elevated percentage of heart rate and systolic blood pressure readings above baseline. Higher mean heart rate and an elevated percentage of heart rate above baseline were associated with physical health symptoms. None of the ambulatory monitoring variables mediated the association between PTSD and physical health outcomes. Findings suggest that the interrelationships among ambulatory autonomic responses, PTSD, and physical health deserve more research attention.

Performance of the UA-787 oscillometric blood pressure monitor according to the European Society of Hypertension protocol

OBJECTIVE

To determine the accuracy of the UA-787 oscillometric blood pressure monitor developed by the A&D Company.

DESIGN

Evaluation of the UA-787 was performed using the new protocol of the European Society of Hypertension. The performance of the monitor was assessed in relation to the subjects' gender, age, skinfold thickness, arm circumference, body mass index and elasticity index of large (C1) and small (C2) arteries.

METHODS

The UA-787 monitor was assessed according to European Society of Hypertension requirements, which are based on four zones of accuracy differing from the mercury standard by 5, 10, 15 mmHg, or more. In all subjects (n=33), indices of large-artery elasticity (C1) and small-artery elasticity (C2) were measured with the HDI/Pulsewave CR-2000 Research Cardiovascular Profiling System.

RESULTS

The UA-787 passed all three phases of the protocol for both systolic and diastolic blood pressure. The mean blood pressure difference between device and the observers was 1.0+/-5.3 mmHg for systolic pressure, and 0.7+/-5.3 mmHg for diastolic pressure. In univariate analysis, the discrepancy between device and the observers was related to forearm circumference (P=0.02) for systolic pressure. For diastolic blood pressure, a significant relationship was found only for heart rate (P<0.01). However, in a multivariable regression analysis no clinical variable was an independent predictor of device-observer discrepancy. In particular, the performance of the UA-787 appeared to be uniform across the whole range of C1 and C2.

CONCLUSIONS

These data show that the A&D UA-787 device satisfies the new recommended European Society of Hypertension accuracy levels for both systolic and diastolic pressure. Its performance is uniform across sub-groups of subjects with different clinical characteristics.

Validation of the A&D UA-631 (UA-779 Life Source) device for self-measurement of blood pressure and relationship between its performance and large artery compliance

OBJECTIVES

To determine the accuracy of the UA-631 (UA-779 Life Source for the American market) blood pressure monitor developed by the A&D Company (Toshimi-ku, Tokyo, Japan).

DESIGN

Device evaluation was performed using a new protocol proposed by the Working Group on blood pressure monitoring of the European Society of Hypertension (ESH). Monitor performance was assessed in relation to subjects' gender, age, skinfold thickness, arm circumference, BMI, and elasticity index of large (C1) and small (C2) arteries.

METHODS

The A&D recorder was assessed according to the various phases of the protocol. Sequential readings were taken for the main validation test. Outcome was classified according to the criteria of ESH recommendations, which are based on four zones of accuracy differing from the mercury standard by 5, 10, 15 mmHg, or more.

RESULTS

The main validation test was performed in 66 subjects for a total of 198 device measurements. The A&D monitor passed all three phases both for systolic and diastolic blood pressure (SBP and DBP). Mean blood pressure difference between device and observers was 2 +/- 5 mmHg for SBP and 1 +/- 3 mmHg for DBP. The absolute discrepancy between device and observers (4 +/- 4 mmHg for SBP, and 2 +/- 2 mmHg for DBP) was related to age (negatively) and to C1 (positively), but in a multivariable regression analysis only C1 remained a significant independent predictor of the absolute device-observer discrepancy.

CONCLUSIONS

These data show that the A&D UA-631 device satisfies the new recommended ESH accuracy levels for both SBP and DBP. Its performance seems to be better in subjects with stiffer arteries.

Ambulatory cardiovascular activity in Vietnam combat veterans with and without posttraumatic stress disorder

The present study investigated the relationship between daily diary affect ratings and ambulatory cardiovascular activity in 117 male Vietnam combat veterans (61 with posttraumatic stress disorder [PTSD] and 56 without PTSD). Participants completed 12-14 hr of ambulatory monitoring and daily diary affect ratings. Compared with veterans without PTSD, veterans with PTSD reported higher negative affect and lower positive affect in daily diary ratings. No differences were detected for mean laboratory initial recordings or mean ambulatory heart rate (HR), systolic blood pressure (SBP), or diastolic blood pressure (DBP). However, compared with veterans without PTSD, veterans with PTSD demonstrated higher SBP and DBP variability and a higher proportion of HR activity (compared with initial recording values) during daily activity. There was a significant Time of Day x Group interaction for mean HR, with a trend for PTSD participants to maintain HR levels during evening hours.

Twenty-four-hour ambulatory blood pressure and heart rate monitoring in combat-related posttraumatic stress disorder

This study examined the cardiovascular correlates of posttraumatic stress disorder (PTSD) in Vietnam combat veterans using 24-hr ambulatory blood pressure and heart rate monitoring. Veterans with PTSD (n = 11) exhibited significantly higher heart rate and diastolic blood pressure across the 24 hr than veterans without PTSD (n = 7) (80.8 vs. 71.9 bpm, and 80.1 vs. 71.5 mm Hg, respectively). Heart rate during sleep was also significantly higher among veterans with PTSD, compared to veterans without PTSD (71.0 vs. 62.7 bpm). These results, based on a more naturalistic measurement methodology used outside the laboratory, support an association between PTSD and increased chronic cardiovascular arousal.

Long-term effects of angiotensin-converting enzyme inhibitors and calcium antagonists on the right and left ventricles in essential hypertension

To compare the effects of chronic antihypertensive treatment on left and right ventricular structure and function, 24 patients with mild to moderate, never-treated hypertension were randomized to receive fosinopril (20 mg daily) or amlodipine (10 mg daily) for 12 months. At baseline and subsequently at the end of third, sixth, and twelfth months, each patient underwent an integrated echocardiographic study and noninvasive ambulatory blood pressure monitoring. Both drugs significantly reduced blood pressure, casual or monitored (p < 0.01), and left ventricular mass index (from 125 +/- 32 to 100 +/- 12 gm/m2 [p < 0.02] with amlodipine and from 106 +/- 18 to 89 +/- 10 gm/m2 [p < 0.02] with fosinopril). The decrease in left ventricular mass was essentially caused by a reduction of ventricular thickness. Free right ventricular wall thickness was also lowered in both groups, more consistently with amlodipine (from 8.0 +/- 2.1 to 6.4 +/- 0.8 mm; p < 0.01), without an increase in plasma natriuretic peptide and insulin concentrations or heart rate. With both treatments, the decrease in ventricular mass was not associated with impairment of systolic function, whereas a trend toward an improvement of Doppler echocardiographic indexes of biventricular diastolic function was observed. In conclusion, both amlodipine and fosinopril induced similar qualitative effects on anatomy and function of both ventricles. The clinical meaning of these observations must be defined further by means of adequately sized prospective trials.

A proposal for scientific validation of instruments for indirect blood pressure measurement at rest, during exercise, and in critical care

OBJECTIVE

The purpose of this study was to provide a critical review and comprehensive outline of published guidelines for the validation of monitors for indirect blood pressure (BP) measurement in light of recent research and practical clinical experience.

METHODS

Studies testing the reliability and validity of BP monitors and available guidelines for validation have been reviewed and compared.

RESULTS

The validation studies of instruments for indirect BP measurement have used a wide variety of sample pools, BP ranges, protocols, reference instruments, and statistical procedures, thereby making it impossible to reach a consensus. Few existing recommendations for validation have been found to be incomplete with respect to BP in various physiological states, sequence of procedures, sample, and statistical analysis.

CONCLUSIONS

A new sequence of procedures for validation, including assessment of instruments during exercise and in critical care, is introduced. Previously suggested sample sizes for study subjects, age, and BP groups, as well as margins of error, are statistically challenged. Insufficiency of linear relationship and aggregate agreement alone in determining the interchangeability between a reference and test instrument is demonstrated by quantification of agreement.

Effect of smoking cessation and relapse on cardiovascular levels and reactivity

This study was designed to investigate the effect of smoking cessation on heart rate, blood pressure, and finger temperature absolute levels and reactivity to a range of laboratory challenges. The 148 quitters (mean age = 43.3 years, mean amount smoked = 24.9 cigarettes per day, mean years smoked = 25.2) completed three assessments: an average of 4 +/- 2.8 days before cessation (Exam 1), an average of 2 +/- 1.0 days after cessation (Exam 2), and an average of 20 +/- 5.5 days after cessation (Exam 3). A nonsmoking group (n = 39) was similarly assessed three times to control for effects related to repeated testing. Comparison of group changes from Exam 1 to Exam 2 indicated that smoking cessation produced a significant decrease in heart rate during rest and during all stressors (mean = -8.9 bpm). Those quitters who remained abstinent or smoked occasionally showed minimal changes in heart rate from Exam 2 to Exam 3, but those quitters who returned to their previous smoking level showed a significant increase in heart rate from Exam 2 to Exam 3. None of the indices of cardiovascular reactivity changed across exams, and neither did absolute levels of blood pressure or finger temperature at rest or during stressors. The possible mechanisms producing a selective heart rate decline after smoking cessation in the absence of pressor or vasodilation effects are discussed.

Differential rates of relapse in subgroups of male and female smokers

Subjects for this study were 265 participants of stop-smoking clinics (mean age = 42.6 years; average number of cigarettes smoked daily = 26.0) who were examined before and immediately after cessation and then followed for 1 year. The objective of this study was to identify subgroups of smokers with different rates of relapse using tree-structured survival analysis, a multivariate approach to classification. Five distinct subgroups that differed with respect to the rate of relapse were identified: (I) subjects (n = 15) with very low precessation cotinine levels (< or = 129 ng/ml), who had an exceptionally low rate of relapse (mean abstinence time = 270 days); (II) women 32 years old and younger (n = 24), who had a very high rate of relapse (mean abstinence time = 30.5 days); (III) women over 32 years old (n = 121), with the next highest rate of relapse (mean abstinence time = 98.9 days); (IV) men 36 years old and younger (n = 31), who had a mean abstinence time of 196.7 days; and (V) men over 36 years old (n = 74), who abstained an average of 130.2 days before relapsing. Relapse curves for all groups (except III vs V) differed significantly from each other, p < 0.05. Results indicate that this approach can identify interactions among individual differences that are variably associated with relapse rates. Identification of relapse subgroups may have important implications for both theories and treatment of smoking relapse.

Comparison of repeated measurement of ambulatory and clinic blood pressure readings in isolated systolic hypertension

Repeated clinic blood pressure measurement was compared with non-invasive ambulatory blood pressure monitoring in 10 elderly subjects with persistent isolated systolic hypertension and 11 normotensive controls. Mean clinic blood pressures +/- Standard Deviation (SD), at visit 1 were 165/81 +/- 12/7 mmHg and 136/87 +/- 14/10 mmHg respectively. Subjects were assessed on three subsequent occasions at weekly intervals. None were receiving antihypertensive or vasoactive medication. Clinical systolic and diastolic blood pressures were consistently higher than the corresponding mean daytime ambulatory blood pressures in both clinical groups at each of the visits. The difference was greater between the systolic pressures than between the diastolic pressures and these differences in systolic pressures were greater in the isolated systolic hypertensives (26 +/- 5 mmHg) than in the normotensives (7 +/- 18 mmHg). Daytime ambulatory readings aggregated from all four visits were normally distributed for both blood pressure components in both clinical groups. In the isolated systolic hypertension group the clinic systolic and diastolic blood pressure measurements corresponded to the 93rd and 85th percentiles of the ambulatory pressures respectively whereas in the normotensives the equivalent percentiles were 69 and 78. These results suggest a pressor response may largely account for the elevated systolic blood pressure seen in elderly subjects with sustained isolated systolic hypertension based on clinic readings.

The impact of automated blood pressure devices on the efficiency of clinical trials

By reducing measurement error, automated blood pressure (BP) devices should enhance the precision of BP estimation and thereby decrease sample size requirements in clinical trials of BP-lowering therapy. Enhanced precision would be particularly relevant to clinical trials assessing the efficacy of nonpharmacological therapies. In the present investigation, resting (clinic) BPs by the Dinamap 8100 (a stationary device) and the Accutracker II (an ambulatory device) were as precise as manual BPs given an equal number of observations by each method. However, both the Dinamap and Accutracker devices underestimated resting diastolic BP in comparison to the manual observers. Estimates of average daytime and 24-hour ambulatory BP, based on large numbers of observations over an extended period of time, were extremely precise. These findings suggest that the use of automated devices to measure resting BP may not reduce samples sizes, whereas use of ambulatory BP devices should reduce samples sizes considerably.