Blood pressure time at target and its prognostic value for cardiovascular outcomes: a scoping review

The proportion of time that blood pressure (BP) readings are at treatment target levels, commonly referred to as time at target or time in therapeutic range (BP-TTR), is emerging as a useful measure for evaluating hypertension management effectiveness and assessing longitudinal BP control. However, method of determination for BP-TTR differs across studies. This review identifies variations in BP-TTR determination methodologies and its potential prognostic value for cardiovascular outcomes. Following PRISMA extension for scoping reviews guidelines, literature was systematically searched in Embase, PubMed, Scopus, Web of Science, and CINAHL. Relevant clinical trials, observational studies, cohort studies, cross-sectional studies, and systematic reviews published in English were screened. Of 369 articles identified, 17 articles were included. Studies differed in the BP targets used (e.g., BP < 140/90 mmHg or 130/80 mmHg; systolic BP within 110-130 mmHg or 120-140 mmHg), BP-TTR measurement duration (range 24 h to 15 years), and calculation method (linear interpolation method, n = 12 [71%]; proportion of BP readings at target, n = 5 [29%]). Regardless of method, studies consistently demonstrated that higher BP-TTR was associated with reduced risk of cardiovascular outcomes. Six of eight studies found the association was independent of mean achieved BP or last measured BP. Despite variation in methods of BP-TTR determination, these studies demonstrated the potential prognostic value of BP-TTR for cardiovascular outcomes beyond current BP control measures. We recommend standardization of BP-TTR methodology, with preference for linear interpolation method when BP measurements are few or less frequent, and proportion of BP readings method when large number of BP readings are available.