(Forbes) — Two studies published in JAMA provide additional but not surprising information about the relationship between obstructive sleep apnea (OSA), hypertension, and the role of continuous positive airway pressure (CPAP).
In the first study, Ferran Barbé and colleagues randomized 725 people with OSA but no daytime sleepiness to either CPAP or no active treatment. Although there were fewer cases of systemic hypertension or cardiovascular events in the CPAP group than in the control group after a median followup of 4 years, this difference did not reach significance.
Incidence of hypertension or cardiovascular events:
- CPAP: 9.20 per 100 person-years (CI, 7.36-11.04)
- Control: 11.02 per 100 person-years (CI, 8.96-13.08)
The authors concluded that the study may have been underpowered to find a significant difference, though they also speculated that CPAP may be less effective in OSA patients without daytime sleepiness.
In the second study, José Marin and colleagues followed 1,889 people without hypertension who had a sleep test. Over a median followup of 12 years, they found that OSA was associated with an increased risk of developing hypertension and that treatment with CPAP was associated with a lower risk of hypertension.
Adjusted hazard ratio for hypertension (compared to controls):
- OSA ineligible for CPAP: 1.33 (CI 1.01-1.75)
- Declined CPAP: 1.96 (CI 1.44-2.66)
- Nonadherent to CPAP: 1.78 (CI 1.23-2.58)
- CPAP therapy: 0.71 (95% CI 0.53-0.94)
The authors commented that their study is “clinically relevant considering that OSA, despite a high prevalence in Western populations, remains overwhelmingly unrecognized and untreated.” Although it was not a randomized study, the results strongly suggest “that OSA may be an independent modifiable risk factor for development of new-onset hypertension.”
In an accompanying comment, Vihesh Kapur and Edward Weaver discuss the limitations of the studies but write that the studies contribute to the considerable body of evidence that “supports the role of identification and treatment of OSA to improve symptoms, quality of life, and cardiovascular end points.”