Relationship Between Framingham 10-Year Cardiovascular Disease Risk Score and Pulse Wave Amplitude Drop Characteristics in a Sleep Clinic Cohort.

Abstract

Pulse oximetry-derived measures of autonomic vascular re-activity during sleep, quantified by pulse wave amplitude drop (PWAD) characteristics such as the PWAD index, have recently been proposed as a biomarker of cardiovascular disease (CVD) outcomes in patients with OSA. Are PWAD characteristics associated with Framingham 10-year CVD risk score in a sleep clinic population? This study examined PWAD characteristics in 725 individuals (38% female; median [interquartile range] age, 52 [39-63] years; BMI, 28.6 [24.9-33.2] kg/m²) who underwent diagnostic polysomnography and had sufficient clinical data to determine CVD status and calculate a Framingham 10-year CVD risk score. Individuals were categorized as either having established CVD (CVD_ESTABLISHED, n = 110) or a Framingham 10-year CVD risk score that was elevated (CVD_ELEVATED, n = 407) or low (CVD_LOW, n = 208). Standard polysomnography variables and PWAD characteristics, including PWAD_INDEX (number of PWAD events that occurred during all sleep stages divided by total sleep time [events/h]) and PWAD_DURATION (average duration of PWAD events [seconds]), were compared between groups. The PWAD_INDEX was lower (P < .01) in the CVD_ESTABLISHED (28.5 [13.2-45.2] events/h) and CVD_ELEVATED (38.7 [20.8-53.0] events/h) groups than in the CVD_LOW group (47.7 [35.7-62.6] events/h). The PWAD_DURATION was longer (P < .01) in CVD_ESTABLISHED (10.4 [8.2-14.5] seconds) and CVD_ELEVATED (8.7 [7.6-10.1] seconds) groups than in CVD_LOW group (8.0 [7.2-8.8] seconds). Similar group differences were observed during rapid-eye movement and non-rapid-eye movement sleep, and in patients with and without OSA. The magnitude difference in PWAD_INDEX and PWAD_DURATION remained similar after adjusting for age, sex, BMI, BP, total sleep time, apnea-hypopnea index, and oxygen desaturation index (adjusted PWAD_INDEX [95% CI] was 34.2 [29.9-38.7] in CVD_ESTABLISHED, 39.4 [37.1-41.6] in CVD_ELEVATED, and 46.6 [42.5-50.7] in CVD_LOW; P < .01). These data indicate that PWAD characteristics may provide a complementary marker of CVD risk in sleep clinic populations with and without OSA. The pathophysiologic mechanisms linking nocturnal PWAD characteristics and CVD risk require further study.