Home Blood Pressure Monitoring - What is the optimal schedule? A systematic review

Background: Self-monitoring of blood pressure (SMBP) has the potential to better estimate underlying blood pressure (BP), is increasingly popular with patients, and is endorsed in hypertension guidelines worldwide. However, there is little agreement as to the optimal self-monitoring schedule. Updating a NICE systematic review, we reviewed the literature regarding the optimum schedule for SMBP in terms of both prediction of future cardiovascular events and the relationship between the number of readings taken and ‘‘true’’ underlying BP, considering the number, timing and frequency of self-monitoring measurements. Methods: Six electronic databases were searched and data were extracted independently by two reviewers from each included paper. For prognostic Abstracts 633 Journal of Human Hypertension studies reporting hazard ratios (HR), the adjusted HRs per 1 mmHg increase in BP were summarised along with the associated outcome. For reliability/ reproducibility studies, correlations reported between SMBP and ambulatory BP measurement (ABPM) were summarised. Methodological quality was assessed using three adapted validated checklists and monitor validation status. Results: From 2,530 unique papers identified, 10 met the inclusion criteria. A further 11 studies were included from the NICE review. In 7/8 prognostic studies, SMBP had predictive value. In 13 reliability/reproducibility studies, all six reporting correlations with ABPM showed strong associations (R ¼ 0.70–0.89) for systolic BP for the best proposed home monitoring schedule. However, there was considerable heterogeneity in population, study quality, and clinical outcomes considered in these studies, and meta-analysis was not possible. 12 studies suggested an optimal number of days to monitor per week (mean 4.75 [SD 1.8]; range 3–7); 12 an ideal number of measurements to be taken each day, (mean 3.7 [SD 1.4]; range 2–6); 10 recommended a total number of measurements to be taken per week (mean 19.8 [SD 9.2]; range 6–30), with some also suggesting how many measurements should be discarded (mean 6.4 [SD 6.8], range 0–18) and how many used (mean 12.2 [SD 6.9], range 5–24). 10 papers advocated taking readings in both the morning and evening, though evidence even here was mixed and marginal. Only one paper assessed the best particular time interval (one minute) to rest between measures. Conclusions: There was limited consensus across the studies identified, other than advocating both morning and evening measurements. Whilst these findings provide a partial endorsement of current guideline recommendations for SMBP, the extent of heterogeneity and concerns over the methodological quality of included studies highlights that further research is necessary before we can recommend a particular schedule to ensure underlying blood pressure is measured adequately.