Obstructive sleep apnea and diurnal nondipping hemodynamic indices in patients at increased cardiovascular risk.

RATIONALE: We hypothesized increasing obstructive sleep apnea (OSA) severity would be associated with nondipping blood pressure (BP) in increased cardiovascular disease (CVD) risk.

METHODS: Baseline data from 298 cardiology patients recruited for a multicenter randomized controlled trial were examined. Dipping was defined as a sleep-related BP or heart rate (HR) reduction of at least 10%. Logistic regression models were fit, adjusting for age, sex, race, BMI, CVD risk factors, CVD, and study site.

RESULTS: There was a statistically significant 4% increase in the odds of nondipping SBP per 1-unit increase in both apnea hypopnea index (AHI) and oxygen desaturation index (ODI). There was no significant relationship between AHI and nondipping mean arterial pressure (MAP); however, a 3% increase in the odds of nondipping MAP per 1-unit increase in ODI was observed [odds ratio (OR) = 1.03; 95% confidence interval (CI) 1.00-1.05]. At severe OSA levels, a 10 and 4% increase in odds of nondipping DBP per 1-unit increase in AHI and ODI were observed, respectively. A 6% [OR = 1.06; 95% CI (1.01-1.10)] increase in nondipping HR odds was observed with each increase in ODI until the upper quartile of ODI.

CONCLUSION: In patients at cardiovascular risk and moderate-to-severe OSA, increasing AHI and/or ODI were associated with increased odds of nondipping SBP and nondipping MAP. More severe levels of AHI and ODI also were associated with nondipping DBP. These results support progressive BP burden associated with increased OSA severity even in patients managed by cardiology specialty care.