Allowing patients who have inadequately controlled high blood pressure to monitor their own blood pressure at home helps their GPs to optimise their management. Patients who self-monitor and visit or talk to their GP when needed for medication adjustments achieve 4mmHg lower systolic blood pressure over 12 months compared with those relying only on the measurements made by a GP without self-monitoring.
Effects are similar if patients write down their measurements to send to the GP or do so via a computerised system.
High blood pressure is a health priority because it increases the risk of serious conditions including stroke and heart disease. Many people with the condition are not achieving recommended blood pressure levels.
This NIHR funded study suggests that self-monitoring of blood pressure could help GPs titrate the dose of medication and could benefit patients through preventing stroke and heart disease
Why was this study needed?
In England, high blood pressure affects more than 1 in 4 adults and increases their risk of diseases such as stroke and heart disease. It is estimated to cost the NHS over £2.1 billion each year.
For most people younger than 80 years, blood pressure is considered to be high if it is 140/90mmHg or more when measured in the clinic.
Only 35% of people in England with high blood pressure have been diagnosed and are achieving recommended blood pressure levels. Better ways to control their blood pressure could improve the situation for those diagnosed.
Previous studies where self-monitoring was used by GPs to help optimise drug treatment for high blood pressure had conflicting results.
What did this study do?
In this TASMINH4 trial, the authors randomised 1,182 adults with inadequately controlled high blood pressure to usual care or self-monitoring with or without telemonitoring.
Usual care patients had their blood pressure measured by their GP as often as the GP wished. With self-monitoring, participants measured their own blood pressure twice in the morning and twice in the evening for the first week of every month. They were told to see their GP if their blood pressure was very high or very low. GPs also reviewed measurements monthly.
With self-monitoring alone, participants wrote down results and posted them to the GP. With telemonitoring, participants sent their results by text to a GP-accessible computer system. It prompted them to see their GP if their blood pressure was very low or very high, or if average readings were above target. For all participants, GPs used blood pressure measurements to help them optimise drug treatment, aiming to achieve NICE’s recommended blood pressure targets.
The main outcome was blood pressure measured at the surgery by a research nurse. There were no important weaknesses in this study, so the results should be reliable.
What did it find?
- After a year, using self-monitoring with or without telemonitoring reduced blood pressure compared with usual care, after taking into account baseline differences.
- Self-monitoring alone reduced systolic blood pressure from baseline by 3.5mmHg more than usual care (95% confidence interval [CI] −5.8 to −1.2mmHg), and diastolic blood pressure by 1.5mmHg more (95% CI −2.7 to −0.2mmHg).
- Self-monitoring plus telemonitoring reduced systolic blood pressure from baseline by 4.7mmHg more than usual care (95% CI −7.0 to −2.4mmHg), and diastolic blood pressure by 1.3mmHg more (95% CI −2.5 to −0.02mmHg).
- Participants in all groups visited their GP a similar number of times. People in the self-monitoring groups were taking slightly more blood pressure medications on average than those in the usual care group. The defined daily dose, a standardised measure, was also higher in the group which used telemonitoring.
- Side effects of blood pressure treatments appeared to be similar between the groups.
What does current guidance say on this issue?
NICE’s 2011 (updated 2016) hypertension guideline recommends that for people identified as having a ‘white coat effect’ (where blood pressure is higher in clinical settings than elsewhere) using home blood pressure monitoring in addition to clinic monitoring is an option. There are no recommendations on exactly what form home monitoring should take. The guideline recommended that more research should be carried out on whether out-of-office monitoring of blood pressure improved treatment response and patient outcomes.
NICE have stated that this guideline is being updated to include, among other things, ‘clearer guidance for home monitoring’ of blood pressure based on new evidence. The revised guideline is scheduled to be published in 2019.
What are the implications?
The findings suggest that self-monitoring is likely to be useful not just for patients who experience the ‘white coat effect’, but also those with uncontrolled high blood pressure.
While the extra reduction in blood pressure was relatively small, the authors estimate that it could reduce stroke risk by about 20%. This is in addition to the benefit from their standard GP care.
To determine whether investment in self-monitoring equipment and telemonitoring systems is justified, a cost-effectiveness analysis is being carried out using data from this trial. The results are likely to inform future guidance in this area.
Citation and Funding
McManus RJ, Mant J, Franssen M, et al; TASMINH4 investigators. Efficacy of self-monitored blood pressure, with or without telemonitoring, for titration of antihypertensive medication (TASMINH4): an unmasked randomised controlled trial. Lancet. 2018;391(10124):949-59.
This project was funded by the National Institute for Health Research Programme Grant for Applied Health Research (RP-PG-1209-10051), Oxford Collaboration for Leadership in Applied Health Research and Care, and Omron Healthcare UK (the manufacturer of the home blood pressure monitoring equipment used in the trial).
Ettehad D, Emdin CA, Kiran A, et al. Blood pressure lowering for prevention of cardiovascular disease and death: a systematic review and meta-analysis. Lancet. 2016;387(10022):957–67.
NICE. Hypertension in adults: diagnosis and management. CG127. London: National Institute for Health and Care Excellence; 2011, updated 2016.
Public Health England. Health matters: combating high blood pressure. London: Public Health England; 2017.
Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre