PS-P04-7: ALERTING REACTION OF BLOOD PRESSURE AND AGE: MAY MEASUREMENT MONTH 2019

Abstract

Objective: The extent of the alerting reaction on systolic blood pressure (BP) measurements has been shown to be related to age and the magnitude of the first reading, with implications for the monitoring and diagnosis of hypertension. We investigated the effects of age on the direction and magnitude of change in both systolic and diastolic BP from the first to subsequent readings, using data from the May Measurement Month (MMM) global BP screening campaign in 2019. Design and method: We examined the relationship between the value of the first reading (BP1) and the change in BP from BP1 to the average (BPA) of the second (BP2) and third readings (BP3) taken at 1 minute intervals in participants with three BP readings. Mixed effects regression models were fit, stratified by age, and using random intercept for country of screening site to account for clustering. This approach was repeated for diastolic and systolic BP. Results: Of the 1,133,008 participants with three BP readings, 58.7% had a decrease in systolic and 54.2% a decrease in diastolic BP from BP1 to BPA. Above an age dependent threshold value in BP1, a higher BP1 was associated with a greater decrease from BP1 to BPA. Older participants on average exhibited relatively smaller changes in systolic BP from systolic BP1 to systolic BP2 for equivalent values of systolic BP1 than younger age groups (Fig.1A). The average difference between diastolic BP1 and diastolic BPA showed a “U shaped” interaction with age such that the largest difference was observed in the youngest and oldest age groups and the smallest difference in those aged 40 to 49 and 50 to 59 years (Fig.1B). These patterns of BPV across values of BP1 and age persisted when the models were adjusted for antihypertensive medication or sex, or if the difference in BP from BP1 to BP2 or BP3 were used as the outcome. Conclusions: Age had a significant and differential modifying effect on the fall in systolic and diastolic BP from first to subsequent readings taken on a single occasion. These results could reflect age related variation in homeostatic capabilities to regulate BP following an initial stress response or differential sizes of alerting response by age. This highlights the importance of taking multiple BP readings when assessing BP, particularly in younger individuals, to avoid overestimation and overdiagnosis.