Association Between Treated and Untreated Obstructive Sleep Apnea and Risk of Hypertension
What is the impact of continuous positive airway pressure (CPAP) therapy on the risk of incident hypertension?
This was a prospective cohort study of 1,889 participants without hypertension who were referred to a sleep center in Zaragoza, Spain, for nocturnal polysomnography between January 1, 1994, and December 31, 2000. Incident hypertension was documented at annual follow-up visits up to January 1, 2011. Multivariable models adjusted for confounding factors, including change in body mass index from baseline to censored time, were used to calculate hazard ratios (HRs) of incident hypertension in participants without obstructive sleep apnea (OSA) (controls), with untreated OSA, and in those treated with CPAP therapy according to national guidelines. The main outcome measure was the incidence of new-onset hypertension.
During 21,003 person-years of follow-up (median, 12.2 years), 705 cases (37.3%) of incident hypertension were observed. The crude incidence of hypertension per 100 person-years was 2.19 (95% confidence interval [CI], 1.71-2.67) in controls, 3.34 (95% CI, 2.85-3.82) in patients with OSA ineligible for CPAP therapy, 5.84 (95% CI, 4.82- 6.86) in patients with OSA who declined CPAP therapy, 5.12 (95% CI, 3.76-6.47) in patients with OSA nonadherent to CPAP therapy, and 3.06 (95% CI, 2.70-3.41) in patients with OSA and treated with CPAP therapy. Compared with controls, the adjusted HRs for incident hypertension were greater among patients with OSA ineligible for CPAP therapy (1.33; 95% CI, 1.01-1.75), among those who declined CPAP therapy (1.96; 95% CI, 1.44-2.66), and among those nonadherent to CPAP therapy (1.78; 95% CI, 1.23-2.58), whereas the HR was lower in patients with OSA who were treated with CPAP therapy (0.71; 95% CI, 0.53-0.94).
The authors concluded that treatment with CPAP therapy was associated with a lower risk of hypertension.
This study suggests that untreated OSA is associated with an increased risk for developing new-onset hypertension and that long-term CPAP therapy is associated with a reduction in such risk. After accounting for body weight changes that occurred in both participants without OSA and with OSA who were treated and untreated, weight gain over a decade did not appear to diminish a protective association of CPAP therapy against development of new-onset hypertension in OSA. These findings suggest that OSA appears to be a modifiable risk factor for new-onset hypertension. The lower risk for new-onset hypertension associated with effective therapy for OSA strengthens the rationale for screening and prompt treatment of OSA in patients who are overweight and obese.
Keywords: Polysomnography, Positive-Pressure Respiration, Spain, Hypertension, Sleep Apnea, Obstructive
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