Abstract Body: Background: Ambulatory blood pressure monitoring (ABPM) provides nuanced information on blood pressure (BP) patterns over time. Whether ABPM is associated with orthostatic changes in BP or BP extremes while supine or standing is unclear.
Objective: To examine the association of 24-hour ABPM patterns with in-office orthostatic systolic BP (SBP) changes, extremely low standing and high supine SBP, or orthostatic hypotension (OH).
Methods: Participants in the Atherosclerosis Risk in Communities (ARIC) Study underwent ABPM and supine and standing in-clinic BP readings (2021-23). OH was defined (using a clinical BP device) as an average supine to standing drop in SBP (≥20 mmHg) (Figure). High average supine SBP (≥160 mmHg) and low average standing SBP (≤110 mmHg) were also measured. SBP variability using ABPM was defined with traditional metrics (Table 1), novel metrics (Table 2), SBP range on ABPM, and times SBP crossed high and low thresholds on ABPM. SBP dyads indicated short-term SBP changes, whereas peaks and valleys indicated gradual SBP changes. Hypotensive episodes and duration were also characterized. (Table 2) Associations of ABPM variability metrics with OH measures were determined via logistic regression adjusted for age, sex, and race-study center.
Results: Of the 285 participants with both ABPM and OH (44% male, mean age 83±3.5 years, mean SBP 129.3±12.8 mmHg), 15% (n=42) had OH. Higher SBP variability on ABPM was associated with low standing (OR = 0.38-0.65) and high supine SBP (OR = 1.20-2.04) (Table 1). Having low standing SBP was associated with a higher number of hypotensive episodes (OR = 2.04), hypotensive duration (OR = 1.21), ABPM SBP counts ≤110 mmHg (OR = 1.26), and inversely associated with ABPM SBP counts ≥160mmHg (OR = 0.10). Additionally, high supine SBP was associated with higher ABPM SBP counts ≥160mmHg (OR = 1.95) and inversely associated with hypotensive duration (OR = 0.59) and higher ABPM SBP counts ≤110 mmHg (OR = 0.33) (Table 2). Lastly, OH was associated with higher ARV (OR = 1.24) and inversely related to hypotensive duration (OR = 0.77) (Figure).
Conclusion: 24-hour ABPM variability metrics did not consistently associate with orthostatic SBP changes; however, they were associated with extremely low standing and high supine SBPs which relate to adverse outcomes in older adults. Future work should evaluate traditional and novel patterns on ABPM to characterize orthostatic changes and symptoms.