Fluctuations in blood pressure measurement: the impact of time of day and ethnicity‐ A HABS‐HD Study

Abstract

AbstractBackgroundVascular risks including hypertension are significant factors in the development of Alzheimer’s and related dementias . Multiple blood pressure (BP) measurements are commonly used in clinical and research practice to assess this vascular risk. Anecdotal evidence suggests that the first BP measurement taken is more elevated than the second measurement as a participant may be nervous about the study. This study explores if the first measurement is elevated compared to the second and then explores the differences between morning and afternoon measurements.MethodData from 1705 participants (non‐Hispanic Whites and Mexican Americans) was collected from a community‐based epidemiological study of aging. The average age was 66, and the average education was 12 years. Participants are scheduled either for AM or PM visit. BP measurements are taken post the consent and then after the participant interview prior to the start of neuropsychological testing. The systolic (SBP) and diastolic blood pressure (DBP) changes were calculated by subtracting the second measurement from the first. T‐tests were performed comparing AM to PM groups. Chi‐square tests compared ethnicity and cognitive status in the AM and PM groups. One‐way ANOVAs examined group differences (ethnicity and AM/PM draw groups) in BP measurement.ResultResults showed significant differences in SBP change between the AM (M = ‐0.52, SD = 12.74) and PM (M = ‐4.03, SD = 10.89); t(1666)= 6.07, p < 0.000) draw and DBP change in the AM (M = 0.16, SD = 7.68) and PM (M = ‐2.32, SD = 6.68); t(1670)=7.09, p <0.000). Chi‐square tests demonstrated significant differences between the AM and PM groups in ethnicity X2(1, N= 1705) = 33.27, p = 0.000. There were no significant differences between the AM and PM regarding cognitive status (normal, MCI, dementia). ANOVAs demonstrated significant differences between the groups in SBP change (F[3, 1672] = 12.76, p <0.000) and DBP change (F[3, 1672] = 17.10, p <0.000).ConclusionThe study results demonstrate that there was a relationship between BP and measurement time, which supports evaluating when BP measurements are taken and how this may affect outcomes. Future studies should examine how the blood pressure measurements relate to current guidelines.