Home blood pressure monitoring: methodology, clinical relevance and practical application: a 2021 position paper by the Working Group on Blood Pressure Monitoring and Cardiovascular Variability of the European Society of Hypertension.

The present paper provides an update of previous recommendations on Home Blood Pressure Monitoring from the European Society of Hypertension (ESH) Working Group on Blood Pressure Monitoring and Cardiovascular Variability sequentially published in years 2000, 2008 and 2010. This update has taken into account new evidence in this field, including a recent statement by the American Heart association, as well as technological developments, which have occurred over the past 20 years. The present document has been developed by the same ESH Working Group with inputs from an international team of experts, and has been endorsed by the ESH.

Examining the effectiveness of telemonitoring with routinely acquired blood pressure data in primary care: challenges in the statistical analysis.

BACKGROUND: Scale-up BP was a quasi-experimental implementation study, following a successful randomised controlled trial of the roll-out of telemonitoring in primary care across Lothian, Scotland. Our primary objective was to assess the effect of telemonitoring on blood pressure (BP) control using routinely collected data. Telemonitored systolic and diastolic BP were compared with surgery BP measurements from patients not using telemonitoring (comparator patients). The statistical analysis and interpretation of findings was challenging due to the broad range of biases potentially influencing the results, including differences in the frequency of readings, 'white coat effect', end digit preference, and missing data. METHODS: Four different statistical methods were employed in order to minimise the impact of these biases on the comparison between telemonitoring and comparator groups. These methods were "standardisation with stratification", "standardisation with matching", "regression adjustment for propensity score" and "random coefficient modelling". The first three methods standardised the groups so that all participants provided exactly two measurements at baseline and 6-12 months follow-up prior to analysis. The fourth analysis used linear mixed modelling based on all available data. RESULTS: The standardisation with stratification analysis showed a significantly lower systolic BP in telemonitoring patients at 6-12 months follow-up (-4.06, 95% CI -6.30 to -1.82, p < 0.001) for patients with systolic BP below 135 at baseline. For the standardisation with matching and regression adjustment for propensity score analyses, systolic BP was significantly lower overall (- 5.96, 95% CI -8.36 to - 3.55 , p < 0.001) and (- 3.73, 95% CI- 5.34 to - 2.13, p < 0.001) respectively, even after assuming that - 5 of the difference was due to 'white coat effect'. For the random coefficient modelling, the improvement in systolic BP was estimated to be -3.37 (95% CI -5.41 to -1.33 , p < 0.001) after 1 year. CONCLUSIONS: The four analyses provide additional evidence for the effectiveness of telemonitoring in controlling BP in routine primary care. The random coefficient analysis is particularly recommended due to its ability to utilise all available data. However, adjusting for the complex array of biases was difficult. Researchers should appreciate the potential for bias in implementation studies and seek to acquire a detailed understanding of the study context in order to design appropriate analytical approaches.

Telemonitoring at scale for hypertension in primary care: An implementation study.

BACKGROUND: While evidence from randomised controlled trials shows that telemonitoring for hypertension is associated with improved blood pressure (BP) control, healthcare systems have been slow to implement it, partly because of inadequate integration with existing clinical practices and electronic records. Neither is it clear if trial findings will be replicated in routine clinical practice at scale. We aimed to explore the feasibility and impact of implementing an integrated telemonitoring system for hypertension into routine primary care. METHODS AND FINDINGS: This was a quasi-experimental implementation study with embedded qualitative process evaluation set in primary care in Lothian, Scotland. We described the overall uptake of telemonitoring and uptake in a subgroup of representative practices, used routinely acquired data for a records-based controlled before-and-after study, and collected qualitative data from staff and patient interviews and practice observation. The main outcome measures were intervention uptake, change in BP, change in clinician appointment use, and participants' views on features that facilitated or impeded uptake of the intervention. Seventy-five primary care practices enrolled 3,200 patients with established hypertension. In an evaluation subgroup of 8 practices (905 patients of whom 427 [47%] were female and with median age of 64 years [IQR 56-70, range 22-89] and median Scottish Index of Multiple Deprivation 2012 decile of 8 [IQR 6-10]), mean systolic BP fell by 6.55 mm Hg (SD 15.17), and mean diastolic BP by 4.23 mm Hg (SD 8.68). Compared with the previous year, participating patients made 19% fewer face-to-face appointments, compared with 11% fewer in patients with hypertension who were not telemonitoring. Total consultation time for participants fell by 15.4 minutes (SD 68.4), compared with 5.5 minutes (SD 84.4) in non-telemonitored patients. The convenience of remote collection of BP readings and integration of these readings into routine clinical care was crucial to the success of the implementation. Limitations include the fact that practices and patient participants were self-selected, and younger and more affluent than non-participating patients, and the possibility that regression to the mean may have contributed to the reduction in BP. Routinely acquired data are limited in terms of completeness and accuracy. CONCLUSIONS: Telemonitoring for hypertension can be implemented into routine primary care at scale with little impact on clinician workload and results in reductions in BP similar to those in large UK trials. Integrating the telemonitoring readings into routine data handling was crucial to the success of this initiative.

Are self-reported telemonitored blood pressure readings affected by end-digit preference: a prospective cohort study in Scotland.

OBJECTIVE: Simple forms of blood pressure (BP) telemonitoring require patients to text readings to central servers creating an opportunity for both entry error and manipulation. We wished to determine if there was an apparent preference for particular end digits and entries which were just below target BPs which might suggest evidence of data manipulation. DESIGN: Prospective cohort study SETTING: 37 socioeconomically diverse primary care practices from South East Scotland. PARTICIPANTS: Patients were recruited with hypertension to a telemonitoring service in which patients submitted home BP readings by manually transcribing the measurements into text messages for transmission ('patient-texted system'). These readings were compared with those from primary care patients with uncontrolled hypertension using a system in which readings were automatically transmitted, eliminating the possibility of manipulation of values ('automatic-transmission system'). METHODS: A generalised estimating equations method was used to compare BP readings between the patient-texted and automatic-transmission systems, while taking into account clustering of readings within patients. RESULTS: A total of 44 150 BP readings were analysed on 1068 patients using the patient-texted system compared with 20 705 readings on 199 patients using the automatic-transmission system. Compared with the automatic-transmission data, the patient-texted data showed a significantly higher proportion of occurrences of both systolic and diastolic BP having a zero end digit (OR 2.1, 95% CI 1.7 to 2.6) although incidence was <2% of readings. Similarly, there was a preference for systolic 134 and diastolic 84 (the threshold for alerts was 135/85) (134 systolic BP OR 1.5, 95% CI 1.3 to 1.8; 84 diastolic BP OR 1.5, 95% CI 1.3 to 1.9). CONCLUSION: End-digit preference for zero numbers and specific-value preference for readings just below the alert threshold exist among patients in self-reporting their BP using telemonitoring. However, the proportion of readings affected is small and unlikely to be clinically important. TRIAL REGISTRATION NUMBER: ISRCTN72614272; Post-results.

Correction: Supported Telemonitoring and Glycemic Control in People with Type 2 Diabetes: The Telescot Diabetes Pragmatic Multicenter Randomized Controlled Trial.

[This corrects the article DOI: 10.1371/journal.pmed.1002098.].

Supported Telemonitoring and Glycemic Control in People with Type 2 Diabetes: The Telescot Diabetes Pragmatic Multicenter Randomized Controlled Trial.

BACKGROUND: Self-monitoring of blood glucose among people with type 2 diabetes not treated with insulin does not appear to be effective in improving glycemic control. We investigated whether health professional review of telemetrically transmitted self-monitored glucose results in improved glycemic control in people with poorly controlled type 2 diabetes. METHODS AND FINDINGS: We performed a randomized, parallel, investigator-blind controlled trial with centralized randomization in family practices in four regions of the United Kingdom among 321 people with type 2 diabetes and glycated hemoglobin (HbA1c) >58 mmol/mol. The supported telemonitoring intervention involved self-measurement and transmission to a secure website of twice-weekly morning and evening glucose for review by family practice clinicians who were not blinded to allocation group. The control group received usual care, with at least annual review and more frequent reviews for people with poor glycemic or blood pressure control. HbA1c assessed at 9 mo was the primary outcome. Intention-to-treat analyses were performed. 160 people were randomized to the intervention group and 161 to the usual care group between June 6, 2011, and July 19, 2013. HbA1c data at follow-up were available for 146 people in the intervention group and 139 people in the control group. The mean (SD) HbA1c at follow-up was 63.0 (15.5) mmol/mol in the intervention group and 67.8 (14.7) mmol/mol in the usual care group. For primary analysis, adjusted mean HbA1c was 5.60 mmol/mol / 0.51% lower (95% CI 2.38 to 8.81 mmol/mol/ 95% CI 0.22% to 0.81%, p = 0·0007). For secondary analyses, adjusted mean ambulatory systolic blood pressure was 3.06 mmHg lower (95% CI 0.56-5.56 mmHg, p = 0.017) and mean ambulatory diastolic blood pressure was 2.17 mmHg lower (95% CI 0.62-3.72, p = 0.006) among people in the intervention group when compared with usual care after adjustment for baseline differences and minimization strata. No significant differences were identified between groups in weight, treatment pattern, adherence to medication, or quality of life in secondary analyses. There were few adverse events and these were equally distributed between the intervention and control groups. In secondary analysis, there was a greater number of telephone calls between practice nurses and patients in the intervention compared with control group (rate ratio 7.50 (95% CI 4.45-12.65, p < 0.0001) but no other significant differences between groups in use of health services were identified between groups. Key limitations include potential lack of representativeness of trial participants, inability to blind participants and health professionals, and uncertainty about the mechanism, the duration of the effect, and the optimal length of the intervention. CONCLUSIONS: Supported telemonitoring resulted in clinically important improvements in control of glycaemia in patients with type 2 diabetes in family practice. Current Controlled Trials, registration number ISRCTN71674628. TRIAL REGISTRATION: Current Controlled Trials ISRCTN 71674628.

Methodology and technology for peripheral and central blood pressure and blood pressure variability measurement: current status and future directions - Position statement of the European Society of Hypertension Working Group on blood pressure monitoring and cardiovascular variability.

Office blood pressure measurement has been the basis for hypertension evaluation for almost a century. However, the evaluation of blood pressure out of the office using ambulatory or self-home monitoring is now strongly recommended for the accurate diagnosis in many, if not all, cases with suspected hypertension. Moreover, there is evidence that the variability of blood pressure might offer prognostic information that is independent of the average blood pressure level. Recently, advancement in technology has provided noninvasive evaluation of central (aortic) blood pressure, which might have attributes that are additive to the conventional brachial blood pressure measurement. This position statement, developed by international experts, deals with key research and practical issues in regard to peripheral blood pressure measurement (office, home, and ambulatory), blood pressure variability, and central blood pressure measurement. The objective is to present current achievements, identify gaps in knowledge and issues concerning clinical application, and present relevant research questions and directions to investigators and manufacturers for future research and development (primary goal).

Mixed methods feasibility study for a trial of blood pressure telemonitoring for people who have had stroke/transient ischaemic attack (TIA).

BACKGROUND: Good blood pressure (BP) control reduces the risk of recurrence of stroke/transient ischaemic attack (TIA). Although there is strong evidence that BP telemonitoring helps achieve good control, none of the major trials have considered the effectiveness in stroke/TIA survivors. We therefore conducted a feasibility study for a trial of BP telemonitoring for stroke/TIA survivors with uncontrolled BP in primary care. METHOD: Phase 1 was a pilot trial involving 55 patients stratified by stroke/TIA randomised 3:1 to BP telemonitoring for 6 months or usual care. Phase 2 was a qualitative evaluation and comprised semi-structured interviews with 16 trial participants who received telemonitoring and 3 focus groups with 23 members of stroke support groups and 7 carers. RESULTS: Overall, 125 patients (60 stroke patients, 65 TIA patients) were approached and 55 (44%) patients were randomised including 27 stroke patients and 28 TIA patients. Fifty-two participants (95%) attended the 6-month follow-up appointment, but one declined the second daytime ambulatory blood pressure monitoring (ABPM) measurement resulting in a 93% completion rate for ABPM - the proposed primary outcome measure for a full trial. Adherence to telemonitoring was good; of the 40 participants who were telemonitoring, 38 continued to provide readings throughout the 6 months. There was a mean reduction of 10.1 mmHg in systolic ABPM in the telemonitoring group compared with 3.8 mmHg in the control group, which suggested the potential for a substantial effect from telemonitoring. Our qualitative analysis found that many stroke patients were concerned about their BP and telemonitoring increased their engagement, was easy, convenient and reassuring. CONCLUSIONS: A full-scale trial is feasible, likely to recruit well and have good rates of compliance and follow-up. TRIAL REGISTRATION: ISRCTN61528726 15/12/2011.

The impact of supported telemetric monitoring in people with type 2 diabetes: study protocol for a randomised controlled trial.

BACKGROUND: Diabetes prevalence is increasing and current methods of management are unsustainable. Effective approaches to supporting self-management are required. The aim of this randomized controlled trial is to establish whether supported telemetric monitoring of glycemic control and blood pressure results in reductions in glycosylated hemoglobin (HbA1c; the primary outcome of a measure of long-term glycemic control) and secondary outcomes of blood pressure and weight among people with poorly controlled diabetes compared to a control group receiving usual care. METHODS/DESIGN: Design: multi-center, randomized controlled trial with embedded qualitative study. Setting: primary care in Lothian, Kent, Glasgow and Borders regions in the UK. Participants: people with type 2 diabetes and confirmed HbA1c>7.5% (58 mmol/mol). Intervention/comparison: randomization to intervention or control groups will be performed by the Edinburgh Clinical Trials Unit. Participants in the intervention group will be shown how to use blood glucose and blood pressure monitors and weighing scales which use Bluetooth wireless technology to transmit readings via modem to a remote server. These participants will be asked to provide at least twice weekly measurements of morning and evening blood glucose and weekly measurements of weight and blood pressure. Measurements will be checked at least weekly by practice nurses who will contact the patients to adjust therapy according to guidelines and reinforce lifestyle advice. Participants in the control group will receive usual care. All participants will receive an individual education session. Follow-up: measurements will be performed at practices 9 months after randomization by research nurses blinded to allocation. The primary outcome measure is HbA1c and secondary outcomes measure are daytime systolic and diastolic blood pressure, weight and cost per quality-adjusted life year. Analysis: intention-to-treat analyses will be performed. The sample size of 320 participants allows for 20% drop-out and has 80% power at 5% significance to detect a 0.5% absolute (6 mmol/mol) fall in HbA1c in the intervention group. The qualitative study will explore the experiences of patients and professionals using the intervention. TRIAL REGISTRATION: Trial registration number ISRCTN71674628.

Telemonitoring-based service redesign for the management of uncontrolled hypertension (HITS): cost and cost-effectiveness analysis of a randomised controlled trial.

OBJECTIVES: To compare the costs and cost-effectiveness of managing patients with uncontrolled blood pressure (BP) using telemonitoring versus usual care from the perspective of the National Health Service (NHS). DESIGN: Within trial post hoc economic evaluation of data from a pragmatic randomised controlled trial using an intention-to-treat approach. SETTING: 20 socioeconomically diverse general practices in Lothian, Scotland. PARTICIPANTS: 401 primary care patients aged 29-95 with uncontrolled daytime ambulatory blood pressure (ABP) (≥135/85, but <210/135 mm Hg). INTERVENTION: Participants were centrally randomised to 6 months of a telemonitoring service comprising of self-monitoring of BP transmitted to a secure website for review by the attending nurse/doctor and patient, with optional automated patient decision-support by text/email (n=200) or usual care (n-201). Randomisation was undertaken with minimisation for age, sex, family practice, use of three or more hypertension drugs and self-monitoring history. MAIN OUTCOME MEASURES: Mean difference in total NHS costs between trial arms and blinded assessment of mean cost per 1 mm Hg systolic BP point reduced. RESULTS: Home telemonitoring of BP costs significantly more than usual care (mean difference per patient £115.32 (95% CI £83.49 to £146.63; p<0.001)). Increased costs were due to telemonitoring service costs, patient training and additional general practitioner and nurse consultations. The mean cost of systolic BP reduction was £25.56/mm Hg (95% CI £16.06 to £46.89) per patient. CONCLUSIONS: Over the 6-month trial period, supported telemonitoring was more effective at reducing BP than usual care but also more expensive. If clinical gains are maintained, these additional costs would be very likely to be compensated for by reductions in the cost of future cardiovascular events. Longer-term modelling of costs and outcomes is required to fully examine the cost-effectiveness implications. TRIAL REGISTRATION: International Standard Randomised Controlled Trials, number ISRCTN72614272.

Telemonitoring based service redesign for the management of uncontrolled hypertension: multicentre randomised controlled trial.

OBJECTIVE: To determine if an intervention consisting of telemonitoring and supervision by usual primary care clinicians of home self measured blood pressure and optional patient decision support leads to clinically important reductions in daytime systolic and diastolic ambulatory blood pressure in patients with uncontrolled blood pressure. DESIGN: Multicentre randomised controlled trial. SETTING: 20 primary care practices in south east Scotland. PARTICIPANTS: 401 people aged 29-95 years with uncontrolled blood pressure (mean daytime ambulatory measurement ≥ 135/85 mm Hg but ≤ 210/135 mm Hg). INTERVENTION: Self measurement and transmission of blood pressure readings to a secure website for review by the attending nurse or doctor and participant, with optional automated patient decision support by text or email for six months. MAIN OUTCOME MEASURES: Blinded assessment of mean daytime systolic ambulatory blood pressure six months after randomisation. RESULTS: 200 participants were randomised to the intervention and 201 to usual care; primary outcome data were available for 90% of participants (182 and 177, respectively). The mean difference in daytime systolic ambulatory blood pressure adjusted for baseline and minimisation factors between intervention and usual care was 4.3 mm Hg (95% confidence interval 2.0 to 6.5; P=0.0002) and for daytime diastolic ambulatory blood pressure was 2.3 mm Hg (0.9 to 3.6; P=0.001), with higher values in the usual care group. The intervention was associated with a mean increase of one general practitioner (95% confidence interval 0.5 to 1.6; P=0.0002) and 0.6 (0.1 to 1.0; P=0.01) practice nurse consultations during the course of the study. CONCLUSIONS: Supported self monitoring by telemonitoring is an effective method for achieving clinically important reductions in blood pressure in patients with uncontrolled hypertension in primary care settings. However, it was associated with increase in use of National Health Service resources. Further research is required to determine if the reduction in blood pressure is maintained in the longer term and if the intervention is cost effective. TRIAL REGISTRATION: Current Controlled Trials ISRCTN72614272.

The case for home monitoring in hypertension.

Although the assessment of cardiovascular risk in individual patients takes into account a range of risk factors, the diagnosis and management of hypertension (high blood pressure) is largely determined by a single numerical value, albeit that often several readings are taken over time. Given the critical impact of a decision to embark on lifelong drug therapy, the importance of ensuring that a blood pressure (BP) record is both accurate and representative is clear. However, there is good evidence that the variability of BP is such that even if measurement is of the highest quality, it can be difficult to say with confidence whether a patient is above or below a treatment threshold. This commentary argues that current BP measurement is inadequate to make the clinical decisions that are necessary and that multiple readings are required to deliver an acceptable degree of accuracy for safe decision-making. This is impractical in a doctor's surgery, and the only realistic long-term strategy is to involve the patient in measuring his or her own BP in their own environment. Evidence is presented that such a strategy is better able to predict risk, is cost-effective for diagnosing hypertension, can improve BP control and is thus better able to protect individuals in the future. In this commentary, I explain why doctors and other healthcare professionals should increase their familiarity with the technology, be aware of its strengths and limitations and work with patients as they become more empowered in the management of their chronic condition, hypertension.

Variability of office, 24-hour ambulatory, and self-monitored blood pressure measurements.

BACKGROUND: The diagnosis of hypertension is difficult when faced with several different blood pressure measurements in an individual. Using the average of several office measurements is recommended, although considerable uncertainty remains. Twenty-four-hour ambulatory monitoring is often considered the gold standard, but self-monitoring of blood pressure has been proposed as a superior method. AIM: Determination of within-individual variability of blood pressure measured in the office, by ambulatory monitoring, and by a week of self-monitoring. DESIGN OF STUDY: Retrospective analysis of a clinical trial of 163 subjects. METHOD: Within-patient variability of office and ambulatory blood pressure was determined from measurements at 0 and 6 weeks. Subjects had performed self-monitoring of blood pressure twice each morning and evening, for at least 6 weeks; variability was determined from the means of week 1 and week 6. RESULTS: The within-individual coefficients of variation (CVs) for systolic blood pressure were: office, 8.6%; ambulatory, 5.5%; self, 4.2%. Equivalent values for diastolic blood pressure were 8.6%, 4.9%, and 3.9%. CVs tended to be lower with longer self-monitoring duration, and higher with longer intervals between self-monitoring. CONCLUSION: Office blood pressure is impractical for precise assessment, as 10-13 measurements are required to give the accuracy required for rational titration of antihypertensive drugs. Twenty-four-hour ambulatory monitoring is better than a single office measurement, but considerable uncertainty remains around the estimate. A week of self-monitoring appears to be the most accurate method of measuring blood pressure, but remains imperfect. Further research may identify superior self-monitoring schedules. Given the inherent accuracy in blood pressure measurement, the importance of considering overall cardiovascular risk is emphasised.

Computerized reporting improves the clinical use of ambulatory blood pressure measurement.

BACKGROUND: Ambulatory blood pressure measurement (ABPM) is being used increasingly in clinical practice. One previous study has shown that there can be considerable variance between expert observers in the interpretation of ABPM data. The purpose of this study was to show whether computer-generated reports with the dablABPM system would provide more consistency in the interpretation of data than reports from expert observers. METHODS: Twenty-six international experts in hypertension were invited to participate and 17 agreed to do so. Twelve ABPMs generated by the Spacelabs device that were considered representative of the patterns likely to be seen in practice were sent to each participant for reporting. The corresponding dabl reports with an automatic interpretation were generated according to the European Society of Hypertension guideline for comparison with the observer reports. Each of the observer-interpreted Spacelabs reports for the 12 ABPM patterns were coded, analysed and compared with the automatically interpreted dablABPM reports. Both sets of data were analysed for interobserver variability, observer v dablABPM consistency and the time taken for observer reportage. The main analysis determined issues of definite disagreement, namely the presence or absence of nocturnal dipping. Further analysis determined the presence or absence of white-coat phenomena and the severity of hypertension. RESULTS: Incorrect diagnoses were made in 13 instances. White-coat hypertension and white-coat effect, although obvious in many instances, were not identified in five ABPMs; the severity of hypertension was not reported in four ABPMs; the severity of nocturnal hypertension was not diagnosed in one ABPM by nine experts and isolated diastolic hypertension was not identified by six experts in two ABPMs. CONCLUSION: This study provides evidence to show that observer variance in reporting ABPMs is common even among experts and that computer-generated interpretative reports of ABPM data improve the diagnostic decisions based on the data generated by 24-h blood pressure recording.

Nocturnal dipping is reproducible in the long term.

OBJECTIVE: To examine the long-term reproducibility of nocturnal dipping as a dichotomous and continuous variable. METHODS: Retrospective review of an ambulatory blood pressure monitor (ABPM) database of approximately 15 000 patients. Reproducibility of ABPM was assessed by repeatability coefficient. Kappa (kappa) statistic and intraclass correlation coefficient were used to quantify dipping as a dichotomous and continuous variable, respectively. RESULTS: There were 512 never-treated patients with two ABPM assessments, a mean of 29 (+/-19) months apart. Blood pressure was 2/0 mmHg (awake) and 2/1 mmHg (asleep) higher on the second ABPM. The repeatability coefficient for awake systolic and awake diastolic pressure was 5.9 and 6.2%, respectively. When the dipper/non-dipper (dichotomous) classification was applied to both ABPMs, dipping status was unchanged in 76% of patients, kappa = 0.29. When nocturnal dip was expressed as a continuous variable, the mean nocturnal dip was 14% and the median absolute change between assessments was 3.8%, intraclass correlation coefficient = 0.60. The time interval between assessments was subdivided into (i) within 6 months, (ii) 6 months to 1 year, (iii) 1-2 years, (iv) 2-3 years and (v) more than 3 years. There was remarkable consistency independent of time interval for dipping expressed as a continuous variable but not as dipper/non-dipper. CONCLUSION: These findings show that in the long term, nocturnal dip is more stable when expressed as a continuous variable. As recent evidence show cardiovascular risk to be inversely related to nocturnal blood pressure in a continuous manner, surely it makes more sense to express nocturnal dip in a similar way to aid stratification of overall cardiovascular risk.