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Update on hypertension - diagnosis, monitoring and guideline treatment targets Prof. Richard McManus, Birmingham, United Kingdom
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Overview Background Routine measurement of blood pressure (is rubbish) Diagnosis of hypertension - ABPM? Management of hypertension – Home ? Treatment targets – any changes? Conclusions
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Stroke Risk increases with age & usual BP Similarly for Heart Disease 40-49 60-69 Low Risk High
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Bottom line BP vs Risk 10 mmHg 38% stroke risk 18% CHD risk
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If you live long enough you get hypertension
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The population is ageing In mid-2008 the median age of the population was 39 years, up from 37 in 1998.
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Routine measurement is often flawed Same population with routine and research measurement
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Blood Pressure varies through the day and between seasons Hypertension. 2006;47:155-161
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Multiple measurements better estimate mean blood pressure
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This variability means that measurement error can drown out the truth
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Even on a single occasion BP drops Approx 1500 patients 24 practices 6 readings at 1min intervals 12 mmHg systolic drop Stable after 5 th reading
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Family Practice 1997; 14:130-135 BP takes some time to settle with repeated measurement over weeks/months
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Many factors affect BP measurement BMJ 2001;322;908-911
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Diagnosing hypertension Traditionally based on clinic measurement Most outcome trials use clinic measures But –Flawed measure (one off from continuum) –Takes weeks / months to make diagnosis
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What about ABPM? Half hourly measurements during the day Better measure usual BP Hourly at night Main outcome is mean day time ABPM Other info available (dipping etc)
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International Thresholds for hypertension diagnosis (clinic and ABPM) Mean daytime BP UK (ABPM) = 135/85 mmHg
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What’s normal for ABPM (and home)? Based on Head et al BMJ 2010 adjust by 5/5 mmHg at lower threshold (stage 1 hypertension, 140/90 mmHg clinic) –ie < 135/85 mm Hg 10/5 mmHg at higher threshold (stage 2 hypertension, 160/100 mmHg clinic) –Ie < 150/95 mmHg
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How do clinic and ABPM compare? Reviewed literature: 2914 studies of which 20 were relevant 7 compared ABPM with clinic monitoring for diagnosis Full details: BMJ 2011;342:d3621 doi: 10.1136/bmj.d3621
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Many people currently potentially misdiagnosed... Worse if only studies around diagnostic threshold used: sensitivity of 86% and specificity of 46%
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What about Home Monitoring? Relative sensitivity and specificity of clinic and home measurement vs ABPM
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Better correlation with end organ damage and outcome (ABPM) 1963 patients Mean FU 5 yrs Baseline ABPM CVD events
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1700 patients, 10 years FU, 150 CVAs Screening = 2 clinic measurements one occasion Home = 25 measurements over 4 weeks Journal of Hypertension 2004, 22:1099–1104 Better correlation with end organ damage and outcome (Home)
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Detection of white coat and masked HT
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But what about costs? Treatment – ↓drug costs Follow up – ↓clinician costs But do additional costs of ABPM out weigh these?
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Is ABPM cost effective? Modelling to evaluate the most cost-effective method of confirming a diagnosis of hypertension in a population suspected of having hypertension ABPM vs Home vs clinic Further details Lovibond et al, Lancet 2011
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Markov Model Health service perspective Lifetime horizon Assume all have raised clinic screening People aged 40 and over
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Markov Model Costs from published sources and NHS Test performance from systematic review Risk calculated using Framingham equation
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Results ABPM most cost effective for every age group
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Results ABPM most cost effective for every age group Robust to wide range of sensitivity analyses
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Results – sensitivity analysis
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Results ABPM most cost effective for every age group Robust to wide range of sensitivity analyses Sensitive to –Assumption of equal test performance –Assumption of no effect of Rx below 140/90 mmHg
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ABPM Don’t forget ABPM need to be validated and have yearly calibration (bhsoc.org.uk website) Lack of night time dipping is additional risk (hence rationale for night readings) Currently limited in PC as most practices either need to refer or only have one ABPM machine Commissioners need to consider whole health economy
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Self Monitoring reduces BP Bray et al. Annals of Medicine 2010 Small reductions in blood pressure from self-monitoring: –SBP by 3.8 mmHg –DBP by 1.5 mmHg
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Self monitoring costs equivalent to usual care BMJ 2005;331;493
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How many measurements? Conclusion = at least 4 days monitoring and discard 1 st European (& UK) Guideline is 1 week, 2 readings bd, discard day 1, take mean (limited rationale)
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What is the place of home monitoring? Management after diagnosis, especially if proven significant white coat effect More outcome and test performance data needed for diagnosis Adjunct to other co-interventions and self management...
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Co-interventions enhance self monitoring effect 5.3 mmHg 2.5 mmHg
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What’s a co-intervention? Nurses Telemonitoring Patient Education Self Management
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Theoretical basis for self management Patients Increased patient involvement in management decisions will result in: Cues to action Adherence Increased self efficacyBehaviour change Better use of medication likely to have most effect Professionals Systematic titration of medication effective Evidence of clinical inertia
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TASMINH2 Research Questions Does self management with telemonitoring and titration of antihypertensive medication by people with poorly controlled treated hypertension result in: 1.Better control of blood pressure? 2.Changes in reported adverse events or health behaviours or costs? 3.Is it achievable in routine practice and is it acceptable to patients?
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The Trial Eligibility –Age 35-85 –Treated hypertension (no more than 2 BP meds) –Baseline BP >140/90 mmHg –Willing to self monitor and self titrate medication Patients individually randomised to self-management vs usual care stratified by practice and minimised on sex, baseline SBP, DM status, Practice GPs determine management
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Intervention Self Monitoring – 1 st week of every month
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Intervention Blood Pressure Targets: –NICE (140/90 or 140/80 mmHg) –minus 10/5 mmHg i.e. 130/85 mmHg or 130/75 mmHg Patients agreed titration schedule with their GP after randomisation Traffic Light system to adjust medication
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Outcomes Follow up at 6 & 12 months Main outcome Systolic Blood Pressure Secondary outcomes: Diastolic BP / costs / anxiety / health behaviours/ patient preferences / systems impact Recruitment target 480 patients (240 x 2) Sufficient to detect 5mmHg difference between groups
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Results Invited (n = 7637) Declined Invitation (n = 5987) Assessed for eligibility (n = 1650) Excluded (n = 1123) Not Eligible (n = 1044) Declined to participate (n=79) Control (n = 264) Received usual care (n = 264) Randomised (n = 527) Analysed (n = 246) Incomplete cases excluded (n = 18) Did not attend follow up (n=14)* Discontinued usual care (n = 0) Intervention (n = 263) Received intervention training (n = 241) Did not attend follow up (n=26)# Discontinued intervention (n = 53) Analysed (n = 234) Incomplete cases excluded (n = 29) 110% recruitment 91% follow up 80% completed intervention
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Baseline Results
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Results - primary outcome SBP
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Results – secondary outcomes DBP
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Results - subgroups
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Results - medications 212 (80%) self managed for full 12 months 148 (70%) made at least one medication change At 12m intervention group prescribed 0.46 (0.34, 0.58) additional antiHT (p=0.001) Main changes seen in thiazides and calcium channel blockers (60% on ACEI/ARB at baseline)
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Results – side effects Similar side effects in intervention vs control
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Treatment targets Observational data shows that achieved blood pressure correlates with CVD outcome Wald meta analysis suggests that treatment effects similar regardless of baseline –But low baseline BP trials almost exclusively secondary prevention
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Treatment targets Little convincing benefit from lower than 140/90 mmHg target in uncomplicated HT Evidence for systolic targets sparse Note reduced targets if out of office measure
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What about old people? Meta analysis – 6701 patients; mean FU 3.5 yrs; mean entry SBP 175 Target 150 mmHg systolic; Mean reduction SBP around 12mmHg Journal of Hypertension 2010, 28:1366–1372
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Bottom Line Consider enhanced use of out of office measurement, especially for diagnosis Ambulatory monitoring for diagnosis is cost effective due to better targeting of treatment Home monitoring useful for ongoing management Patients can do it too! 140/90 mmHg best evidence target unless secondary prevention or over 80
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