Apnea Hypopnea Index During REM Sleep Associated With Hypertension

A new study has identified a likely positive association between apnea hypopnea index during rapid eye movement (REM AHI) sleep and hypertension in people with obstructive sleep apnea (OSA). In particular, female patients were more affected by this interplay of factors.

Findings appeared in Nature and Science of Sleep.

Hypertension is one of the most prevalent cardiovascular diseases associated with OSA, with more than 50% of patients with OSA estimated to have underlying hypertension. The researchers of the current study reviewed medical records of patients with diagnosed OSA at the sleep center of Tianjin Medical University General Hospital between January 1, 2017, and December 31, 2020.

Patients (N = 808) were excluded if they were younger than 18 years, had severe cardiopulmonary or another disease that may lead to hypoxia, had previous treatment for sleep-disordered breathing, had central/mixed sleep apnea diagnosed by polysomnography (PSG), had incomplete data, and had total sleep time of less than 4 hours. Daytime sleepiness was evaluated with the Epworth sleepiness scale (ESS) score, and a PSG was administered—both at the sleep center.

Apnea was defined as a stop of airflow for at least 10 seconds, with continued effort or lack of effort to breathe in that time. Hypopnea was defined as a reduction in airflow with at least a 3% decrease in oxygen desaturation from baseline. Of the study’s participants, 416 had OSA and 392 did not.

Patients with hypertension were older (50.35 vs 43.90 years), considered more obese (30.84 vs 29.07 kg/m²), and had a higher proportion of family history of hypertension (73.3% vs 49.0%) vs patients without hypertension. Patients with OSA and hypertension also had higher ESS scores, AHI, REM AHI, AHI during non-REM stage, and oxygen desaturation index. There were no significant differences in the total sleep time, longest apnea time, mean apnea time, longest hypopnea time, and percentage of REM sleep stage in total sleep time.

A multivariate binary stepwise logistic regression analysis identified associations between age (odds ratio [OR], 1.057; 95% CI, 1.043-1.070), waist circumference (OR, 1.043; 95% CI, 1.029-1.057), family history of hypertension (OR, 3.604; 95% CI, 2.598-5.000), and REM AHI (OR, 1.007; 95% CI, 1.000-1.014) hypertension in patients with OSA.

The researchers also found that an increasing level of REM AHI (OR, 1.61 for tertile 3 vs tertile 1; 95% CI, 1.07-2.42) was associated with a higher risk of hypertension. SD increments of REM AHI were associated with an increased risk of hypertension in patients with OSA (OR, 1.007; 95% CI, 1.001-1.014), and REM AHI was positively related to the risk of hypertension in women.

Percentage of hypertension in the cohort increased with an increase in cross-sectional REM AHI tertiles (42.91% in tertile 1, 52.35% in tertile 2, and 59.92% in tertile 3), and the prevalence of hypertension increased with increasing tertiles of REM AHI in women (40.00% in tertile 1, 50.00% in tertile 2, and 68.13% in tertile 3).

There were some limitations to this study. Causality could not be identified due to the cross-sectional nature of the study, and confounding factors, such as dietary habits, labor intensity, economic status, and psychological conditions were not taken into account for this analysis. The study also focused on patients with OSA, which means it could not be expanded to other groups.

The researchers concluded that their study identified a positive and significant association between REM AHI and hypertension in patients with OSA, especially in female patients.

“Additional research is needed to explore whether such patients need to be treated,” they emphasized.

Reference

Wang L, Wei D, Zhang J, Cao J, Zhang X. High rapid eye movement sleep apnea hypopnea index is associated with hypertension in patients with obstructive sleep apnea. Nat Sci Sleep. 2022;14:1249-1258. doi:10.2147/NSS.s369614