Race And CPAP Effectiveness (RACE)

Obstructive sleep apnea (OSA) is a major public health problem in the U.S. and more than 35% of Veterans are at high risk for OSA. OSA is associated with progression of hypertension, an important health problem in Veterans. African Americans with OSA are at increased risk for poorly controlled hypertension and its health consequences. Implementing a care plan to increase the percentage of Veterans in whom blood pressure goals are achieved has been prioritized by Veterans Administration hospitals. Recent studies show that hypertension control can be improved with continuous positive airway pressure (CPAP) treatment of OSA. The aim of this proposal is to examine and compare the effects of CPAP treatment on 24-hour arterial blood pressure and central aortic blood pressure (measured non-invasively with a cuff on the upper arm) in African American and other Veterans.

Obstructive Sleep Apnea (OSA) and hypertension are both common and severe problems in African American individuals (as noted in the International Society on Hypertension in Blacks consensus statement). CPAP treatment of OSA is effective in controlling hypertension in patients with OSA, but has not been studied in African Americans, a high-risk population with potentially large health gains. This is an area of significance because poorly controlled hypertension leads to progression of cardiovascular disease (CVD) and morbidity in this population. By identifying CPAP treatment-response and relevant moderators of this response in African Americans with hypertension and OSA, targeted treatment of OSA can be implemented, reducing the excess burden of CVD. The investigators will determine the relative magnitude of hypertension response to CPAP treatment (ambulatory blood pressure and central aortic blood pressure) in 220 African American and Veterans of other race(s) with hypertension and newly diagnosed OSA (specific aim 1). The investigators will measure changes in pathogenic biomarkers (urinary cumulative sympathetic nervous system activity and oxidative stress) that are responsive to CPAP treatment in addition to hypertension assessments. Further, the investigators will examine the role of excessive daytime sleepiness (EDS), a potentially important moderator of treatment response, in these two patient populations (specific aim 2). Finally, the investigators will adjust the outcomes assessment for the anticipated biological heterogeneity among self-identified African Americans by measuring genetic ancestry (exploratory aim). This award will provide the foundation for the goals of this research program to reduce CVD disparity in diverse populations with targeted treatment of OSA.

Mean systolic and diastolic blood pressure measured over 24 hours with ambulatory monitor (Spacelabs). The change in blood pressure values were calculated as 3 months BP - baseline BP. The mean and standard deviation in the sample are noted below.

Central aortic blood pressure (CABP) measured noninvasively with a cuff (SphygmoCor XCEL). The change in CABP values were calculated as 3 months CABP - baseline CABP. The mean and standard deviation in the sample are noted below.

Urine samples from participants over 24 hours will be analyzed for catecholamines and overnight sample will be partitioned for measurement of oxidative stress. The change in urine catecholamine values were calculated as 3 months - baseline. The mean and standard deviation in the sample are noted below.

Inclusion Criteria: Self-identified African American and other Veterans (of self-identified race other than African American) Age: 30-70 years Hypertension Apnea hypopnea index (AHI) 15/hour on home sleep apnea test Exclusion Criteria: Past/current treatment of Obstructive Sleep Apnea or other primary sleep disorders Active uncontrolled medical conditions Shift work in past 6 months Current drug use Pregnancy

Imayama I, Gupta A, Yen PS, Chen YF, Keenan B, Townsend RR, Chirinos JA, Weaver FM, Carley DW, Kuna ST, Prasad B. Socioeconomic status impacts blood pressure response to positive airway pressure treatment. J Clin Sleep Med. 2022 May 1;18(5):1287-1295. doi: 10.5664/jcsm.9844.