Abstract Body: Background:
Activities throughout the 24-hour day, including sleep, physical activity, and sedentary time, are independently linked with cardiovascular health. However, these behaviors are dynamic and interrelated, and few studies have collectively examined their relations with cardiovascular disease (CVD). Our objective was to examine associations between waist-worn accelerometer-measured 24-hour activity and incident CVD and CVD mortality in a multiethnic cohort of older women.

Methods:
Women (n=3,897; mean age: 78.5 years, 33% African American, 17% Hispanic/Latino) enrolled in the Women’s Health Initiative OPACH (Objective Physical Activity and Cardiovascular Health) study wore an Actigraph GT3X+ accelerometer for 7 days in 2012-2014 and were followed through February 2024 for physician-adjudicated incident CVD (non-fatal or fatal myocardial infarction, non-fatal or fatal stroke, or death attributable to any CVD) and CVD mortality. Estimates of sleep duration, wake after sleep onset (WASO), light physical activity, moderate to vigorous physical activity, and sedentary time were scaled to 24-hours and treated as proportions of the 24-hour day. Mixture model-based clustering identified clusters of 24-hour activity behaviors. Bayesian information criterion was used to select the optimal cluster number (1–9). Women with prevalent CVD were excluded from analyses (n=348). We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) relating 24-hour activity profile clusters with CVD and CVD mortality. Models were adjusted for demographics, multimorbidity, and CVD risk factors.

Results:
Over a median follow-up of 9.8 years, 774 incident CVD cases occurred, including 515 CVD deaths. Clustering analyses identified five 24-hour activity profiles (Figure 1A). In models adjusted for demographics, 24-hour activity profiles characterized by longer sleep, less physical activity, and greater sedentary time were associated with increased risk of CVD (Profile 2: HR: 2.02; 95% CI: 1.27, 3.21) and CVD mortality (Figure 1B). After adjustment for multimorbidity and CVD risk factors, the HR (95% CI) was 1.59 (1.00, 2.54) for CVD and 2.30 (1.28, 4.15) for CVD mortality.

Conclusions:
In older women, 24-hour activity profiles that include poor sleep, low physical activity, and high sedentary time increase risk of CVD and CVD mortality. Results from novel 24-hour analyses may highlight new lifestyle strategies for CVD prevention.