Long-term Adherence to CPAP May Reduce Blood Pressure in Patients With OSA

Long-term adherence to continuous positive airway pressure (CPAP) therapy may significantly reduce blood pressure in at-risk patients with obstructive sleep apnea (OSA), according to study findings published in Scientific Reports.

With an estimated 1 in 15 adults and up to 6% of adolescents affected by OSA in the United States today, there have been several reports tying the condition with adverse cardiovascular outcomes, such as high blood pressure, accelerated vascular aging, and stroke.

In fact, researchers note that nearly 50% of patients with OSA have hypertension and 37% to 56% of patients with hypertension have comorbid OSA.

Amid limited research suggesting CPAP therapy could reduce blood pressure in patients with OSA, the study authors sought to explore this association long term in a longitudinal study with a large sample size.

In the study, 918 patients with OSA (mean [SD] age, 53.4 [12.7] years; mean [SD] apnea–hypopnea index [AHI], 40.0 [19.5] times/h) underwent CPAP therapy at RESM Sleep and Medical-Care Clinic, in Kanagawa, Japan, and were followed for 24 months to examine CPAP adherence, as well as longitudinal changes in blood pressure and body weight between June 2013 and June 2018.

CPAP usage of participants were collected over the course of 30 nights prior to each follow-up visit (1, 3, 6, 12, and 24 months). Mixed-effect logistic regression models were used to compare the relationship between CPAP adherence and blood pressure for patients identified as having adequate (≥4 hours for 70% or more of the follow-up time) and poor adherence.

An interaction term, adequate CPAP adherence*time, was used to examine the association of CPAP adherence with trajectories of systolic/diastolic blood pressure and body weight over time.

At baseline, mean systolic and diastolic blood pressure levels were 133.6 mm Hg and 86.7 mm Hg, respectively. The rate of adequate CPAP usage at 24 months among the study participants was 62.3%.

For both patient groups, body weight was shown to increase over the 24-month observation period from 77.3 kg to 78.3 kg, but no significant longitudinal association was found between time*adequate adherence and body weight (β = −0.02; P = .59).

After adjusting for multiple confounding variables, results based on mixed-effect logistic regression models exhibited a significant reduction in diastolic blood pressure among patients with adequate CPAP adherence during the 24-month follow-up period (β = –0.13; P = .03), compared with patients reporting poor CPAP adherence. No significant association was found regarding time*adequate adherence and systolic blood pressure (β = −0.14; P = .12)

“The coefficient estimate of β = –0.13 indicates that blood pressure decreased by (an average of) 0.13 mm Hg every month,” explained researchers.

Furthermore, no significant association was found between CPAP adherence and weight loss (β = −0.02; P = .59).

Addressing the study findings, researchers concluded that a significant potential reduction in cardiovascular morbidity and mortality may be expected in patients with OSA and normal blood pressure who adhere to CPAP therapy long term.

“However, more research is recommended to further clarify the clinical relevance of our findings,” they added.

Reference

Shirahama R, Tanigawa T, Ida Y, et al. Long‑term effect of continuous positive airway pressure therapy on blood pressure in patients with obstructive sleep apnea. Sci Rep. Published online September 27, 2021. doi:10.1038/s41598-021-98553-0