Nightly variation in OSA severity and next day blood pressure

<bold>Introduction:</bold> High night-to-night variability in obstructive sleep apnea (OSA) severity may importantly contribute to cardiovascular disease. <bold>Objectives:</bold> This study evaluated the effects of acute AHI changes on next day blood pressure (BP). <bold>Methods:</bold> Data were acquired from 14,368 participants who used a validated under-mattress sleep sensor and a home BP monitor between January 2020 and September 2023. Individuals with an average AHI < 5 events/h were excluded. Forward and backward directed analyses using linear mixed models with random intercept on participant number, examined AHI and BP differences (ΔAHI and ΔBP) between a given night and the average of the prior and next 14 nights/day (Figure top). <bold>Results:</bold> 9,776 participants (55±12 years, 90% males) had an AHI ≥5 events/h. Each participant had a median of 157 concomitant sleep and BP measures. In forward analysis (see Figure), a 10 event/h increase in AHI on a given night was associated with a 0.20 (95%CI; 0.19 to 0.21) and 0.31 (0.29, 0.32) mmHg increase in next day diastolic and systolic BP. In backward analysis, the ΔAHI was also significantly associated with a ΔBP, but the effect size was 3 to 4 times smaller. <bold>Conclusions:</bold> Given the difference in effect size between the forward and backward analysis, the association between an acute increase in AHI with an acute increase in blood pressure may be causal, although the effect of potential confounders (e.g. alcohol intake) cannot be discounted. <fig><object-id>erj;64/suppl_68/OA5434/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>