Time spent at blood pressure target and the risk of death and cardiovascular diseases

Abstract

Background: The time a patient spends with blood pressure at target level is an intuitive measure of successful BP management, but population studies on its effectiveness are as yet unavailable.

Method: We identified a population-based cohort of 169,082 individuals with newly identified high blood pressure who were free of cardiovascular disease from January 1997 to March 2010. We used 1.64 million clinical blood pressure readings to calculate the TIme at TaRgEt (TITRE) based on current target blood pressure levels.

Result: The median (Inter-quartile range) TITRE among all patients was 2.8 (0.3, 5.6) months per year, only 1077 (0.6%) patients had a TITRE ≥11 months. Compared to people with a 0% TITRE, patients with a TITRE of 3-5.9 months, and 6-8.9 months had 75% and 78% lower odds of the composite of cardiovascular death, myocardial infarction and stroke (adjusted odds ratios, 0.25 (95% confidence interval: 0.21, 0.31) and 0.22 (0.17, 0.27), respectively). These associations were consistent for heart failure and any cardiovascular disease and death (comparing a 3-5.9 month to 0% TITRE, 63% and 60% lower in odds, respectively), among people who did or did not have blood pressure 'controlled' on a single occasion during the first year of follow-up, and across groups defined by number of follow-up BP measure categories.

Conclusion: Based on the current frequency of measurement of blood pressure this study suggests that few newly hypertensive patients sustained a complete, year-round on target blood pressure over time. The inverse associations between a higher TITRE and lower risk of incident cardiovascular diseases were independent of widely-used blood pressure 'control' indicators. Randomized trials are required to evaluate interventions to increase a person's time spent at blood pressure target.

Fig 1. Definition of newly identified hypertension, average annual time at target (TITRE) and fatal and non-fatal cardiovascular events.

¹ BP <140/90 mmHg, or <150/90 for patients aged 60 years or more without diabetes and chronic kidney disease. BP: blood pressure. CVD: cardiovascular disease. ² For each patient, the days that blood pressure was at target between two consecutive measures were summed to calculate the percent time at target for each follow-up year, and then averaged over follow-up years. Details are described in S1 Method. ³ Incident cardiovascular disease include: myocardial infarction, stroke (including ischemic stroke, intracerebral hemorrhage and sub-arachnoid hemorrhage), heart failure, angina, atrial fibrillation, transient ischemic attack, peripheral artery disease, abdominal aortic aneurysm and cardiovascular and non-cardiovascular mortality.) It is unclear to what the (1) refers to in the figure.

Fig 2. Time at target (TITRE) distribution in patients with recorded TITRE (N = 150130).

*Median 2.8 (0.3, 5.6) months.

Fig 3. Patient characteristics and their association with a higher or lower TITRE (%).

Fig 4. Associations between categorical time at target (TITRE) and primary (composite of cardiovascular mortality, myocardial infarction and stroke, incident heart failure and any cardiovascular diseases) and secondary (stable angina, peripheral artery disease, and all-cause mortality) study endpoints (n = 169082).