PHILADELPHIA—Many, but not all, patients with obstructive sleep apnea see a decline in blood pressure with positive airway pressure treatment. A new study raised the question of whether the BP response related to sleep apnea therapy might be linked to obesity.

The study in the Journal of Clinical Hypertension involved 188 adults with OSA undergoing 24-hour BP monitoring and 24-hour urinary norepinephrine collection at baseline.1

University of Pennsylvania and Cpl. Michael J. Crescenz VAMC-led researchers assessed obesity by waist circumference, body mass index and abdominal visceral fat volume. After four months, they then reassessed participants adherent to PAP treatment.

Defined as primary outcomes were 24-hour mean arterial pressure  and 24-hour urinary norepinephrine level.

Results indicated that obstructive sleep apnea participants had a significant reduction in 24-hour MAP following PAP treatment (-1.22 [95% CI: -2.38, -0.06] mm Hg; P = 0.039). Yet, the study team identified no significant correlations with any of the three obesity measures for BP or urinary norepinephrine measures at baseline in all OSA participants or for changes in BP measures in participants adherent to PAP treatment. In addition, changes in BP measures following treatment were not correlated with baseline or change in urinary norepinephrine.

The study reported similar results when BP or urinary norepinephrine measures were compared between participants grouped using the sex-specific median of each obesity measure.

In fact, greater reductions in urinary norepinephrine were correlated with higher waist circumference (rho = -0.21, P = 0.037), with a greater decrease from baseline in obese compared to nonobese participants (-6.26 [-8.82, -3.69] vs -2.14 [-4.63, 0.35] ng/mg creatinine; P = 0.027), the authors noted.

“The results indicate that the BP response to PAP treatment in adults with OSA is not related to obesity or urinary norepinephrine levels,” researchers concluded.

1.    Kuna ST, Townsend RR, Keenan BT, Maislin D, et. Al. Blood pressure response to treatment of obese vs non-obese adults with sleep apnea. J Clin Hypertens (Greenwich). 2019Oct;21(10):1580-1590. doi: 10.1111/jch.13689. Epub 2019 Sep 18. PubMed PMID:31532580.