P3442Cognitive impairment: a mediator for the relationship of visit-to-visit blood pressure variability and long sleep duration with cardiovascular death in the elderly

Abstract

Background: Visit-to-visit blood pressure (BP) variability, short or long sleep duration and cognitive impairment were shown to be associated with cardiovascular disease, although there were no studies that reported those comprehensive relationships for the cardiovascular disease. Here, we investigated the impact of visit-to-visit BP variability, sleep duration and cognitive impairment on the cardiovascular disease in the elderly at high-risk of cardiovascular disease. Purpose: To investigate the relationships among visit-to-visit BP variability, sleep duration, cognitive impairment and cardiovascular disease in the elderly at highrisk of cardiovascular disease. In addition, the issue whether cognitive impairment moderates the relationships of visit-to-visit BP variability and sleep duration with cardiovascular disease was analyzed. Methods: Among the total population of 1723 peoples in the Soryo Town, BP measurements, assessment of sleep duration and cognitive function were performed in 201 subjects (mean age 79.9 yrs at baseline, 75% females) with one or more cardiovascular risk factors. Based on 12 visits (1×/month for 1 year), we calculated visit-to-visit BP variability expressed as the standard deviation (SD) and delta (maximum-minimum) BP. The cognitive function was evaluated using a mini-mental state examination (MMSE), whereas self-reported sleep duration questionnaire was used to classify the patients according to sleep duration. Results: In the Cox-regression analysis adjusted for age, gender, body mass index, diabetes mellitus, low-density lipoprotein and fasting blood glucose, delta systolic BP (SBP) (HR: 7.4, 95% CI: 1.3-44, p<0.05) and long sleep duration (>9h per night) (HR: 1.03, 95% CI: 1.003-1.064, p<0.05) were significant predictors of cardiovascular death during the mean 6.1-year follow-up. Consistent with cognitive impairment (MMSE score less than 25) as a mediator of the relationships of delta SBP and long sleep duration, the inclusion of cognitive impairment in that multivariate Cox model appreciably attenuated those association (p=0.07 and p=0.3, respectively). Conclusions: Exaggerated visit-to-visit SBP variability and long sleep duration were significant predictors of cardiovascular death in high-risk elderly patients at cardiovascular disease. Cognitive impairment was suggested to serve as a mediator for the relationship of visit-to-visit SBP variability and long sleep duration with cardiovascular outcome.