(47) Evaluating a home blood pressure protocol to minimize the white coat effect

Objective : Home blood pressure monitoring (HBPM) is effective for confirming a hypertension diagnosis and monitoring medication therapy to reduce influence of the white coat effect. However, there is limited evaluation of home BP method assessment including whether to keep or discard the first day of home BP readings or if the first BP reading in a consecutive series should be discarded. We have integrated patient self-monitoring blood pressure into office-based hypertension management at a federally qualified community health center. This is a retrospective evaluation to determine if our current methods reliably minimize the white coat effect and ensures reproducibility when measuring from day to day.

Methods: Retrospective review of 196 written home BP log sheets of patients participating in a HBPM program where instructions are to take BP readings in triplicate (3 times in a row) in AM and PM for 10 days.
Repeated measures ANOVA analyses evaluated differences in how the triplicate BP readings could be interpreted as well as comparing BP averages between days.

Results: The first of 3 BP readings taken in triplicate by a patient at home is significantly higher compared to the averaged second and third readings (p < 0.05) and all 3 readings averaged together (p < 0.05). This is consistent for AM or PM readings, and for SBP or DBP. Comparing the overall BP average from day to day suggests that Day 1 (p < 0.05) and Day 2 (p < 0.05) is higher than all other days. There was no difference between Day 3 through Day 10.

Conclusions: When evaluating patient home BP readings, discarding the first BP reading taken in a series and the first 2 full days of BP readings should be considered.