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Among the 1.13 billion people globally with high blood pressure little is known about sustaining blood pressure control in general populations. In clinical practice, and in research in unselected populations, the convention has been to measure control as a single ‘snap shot’ without considering the longitudinal time course of blood pressure control mirroring that known be important in trial settings.

To address the knowledge gap, the present study hypothesised that time spent at target blood pressure levels (TIme at TaRgEt, TITRE) might be a clinically useful measure of hypertension management quality and ‘real world’ treatment effectiveness. We address two previously unanswered questions:

• What is the average time in a year that BP remains at the treatment target in hypertensive patients? And does TITRE identify a greater burden of sub-optimal blood pressure control than has previously been recognised?
• Is TITRE independently associated with cardiovascular endpoints and mortality? And if so what are the implications for hypertension management guidelines

Unique data

We are excited to offer answers to these questions which we believe are striking and timely, with current debates focussed on lower target BP levels. We analysed 1.64 million blood pressure measures over a median of 4.9 years of follow-up from 169,082 newly- identified hypertensive patients in a population based study in the UK, which incentivises BP control monitoring.

We demonstrate that:

• Using TITRE identifies sub-optimal blood pressure control in nearly every patient. Only 0.6%(n=1077) patients had a TITRE of 11 months; on average the blood pressure target was sustained for only about 3 months per year.
• Higher TITRE was strongly associated in a stepwise fashion with lower risk of the composite of cardiovascular death, myocardial infarction and stroke. For example, compared to patients with a TITRE of 0% TITRE, patients with a TITRE of <3 months, 3-5.9 months, 6-8.9 months, and 9-11.9 months had multiple adjusted odds ratio of 0.47 (95% confidence interval: 0.40 to 0.56), 0.25(0.21,0.31), 0.22(0.17,0.27) and 0.26(0.18,0.36).
• Higher TITRE was associated with cardiovascular endpoints independent of and significant greater than other blood pressure control measures, including a snapshot control status within the first year, mean blood pressure, and visit-to-visit blood pressure variability.
• In every 100,000 hypertensive individuals in the UK, an estimated 1824 cases of any cardiovascular disease and deaths may be prevented or deferred over five years had patients experienced the standardized event rate of one level higher TITRE category then their own.

Practice changing implicationsÌý

Our study supports the inclusion in clinical guidelines of recommendations on the frequency of BP measurement on follow up: currently no clinical guidelines2,3 have such a recommendation. It also provides evidence of the need for clinicians to consider longitudinal patterns of blood pressure control.

Research challenge

Readers reasonably ask what is best for patients: strategies aimed at increasing TITRE by 3 months or more or strategies aimed at achieving a 20mmHg lower BP target? Following the SPRINT trial there is a major focus on lowering the target BP. The updated clinical guideline for high blood pressure management recommends a lower diastolic blood pressure target. If improving TITRE cannot be achieved at higher target levels, it would seem even more challenging to expect clinicians, outside the context of trial settings, to deliver and sustain control at even lower BP target levels.
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Chung SC, Pujades-Rodriguez M, Duyx B, Denaxas SC, Pasea L, Hingorani A, Timmis A, Williams B, Hemingway H. Time spent at blood pressure target and the risk of death and cardiovascular diseases.ÌýPublished: September 5, 2018.Ìý