Comorbid Insomnia, Sleep Apnea and the Risk for All-Cause Mortality and CVD

Patients with comorbid insomnia and sleep apnea more often have hypertension and cardiovascular disease (CVD) and have a significantly increased risk of all-cause mortality compared with individuals without insomnia and obstructive sleep apnea (OSA), a study in the European Respiratory Journal suggests.

The study included 5236 participants pooled from population-based studies. All participants underwent a home-based polysomnography recording between 1995 and 1998. Additionally, participants completed questionnaires on sleep habits and quality of life.

The investigators defined insomnia as self-reported nocturnal symptoms such as difficulties in falling asleep, maintaining sleep, and/or early morning awakenings from sleep for 16 times per month or more. Sleep apnea was identified as an apnea-hypopnea index at least 15 events/hour of sleep. The researchers evaluated the association between comorbid insomnia and sleep apnea and all-cause mortality (n=1210) over a 15-year follow-up period in multivariable adjusted Cox proportional hazard models. The prevalence of hypertension, CVD, and diabetes mellitus were investigated using logistic regression controlling for age, BMI, and gender.

Approximately 52% (n=2708) of participants did not have insomnia or OSA and were classified as the control group. A total of 170 (3%) participants had only insomnia, while 2221 (42%) had OSA alone. Another 137 (3%) had comorbid insomnia and sleep apnea.

Compared with the control group, participants with comorbid insomnia and sleep apnea had a greater prevalence of hypertension (odds ratio [OR], 2.00; 95% CI, 1.39-2.90) and CVD (OR, 1.70; 95% CI, 1.11-2.61). Although participants with insomnia alone and OSA alone had a higher risk of hypertension compared with controls, there was no difference between the groups in regard to cardiovascular disease. The prevalence of diabetes did not differ between groups.

Comorbid insomnia and sleep apnea was associated with a 47% (hazard ratio, 1.47; 95% CI, 1.06-2.07)) increased risk of mortality compared with the control group. According to the investigators, the association between comorbid insomnia and sleep apnea and mortality “was consistent across multiple definitions of OSA and insomnia.”

Given that the study lacked sufficient data to identify participants with chronic insomnia lasting 3 months or more, the study was limited in its ability to evaluate the association between chronic nocturnal and daytime symptoms and mortality.

The researchers said that “it remains to be determined if these associations are causal,” adding that treatment with cognitive behavioral therapy for insomnia, continuous positive airway pressure, or combination therapy “can effectively decrease mortality risks” in individuals with comorbid insomnia and sleep apnea.

Disclosure: Multiple authors declared affiliations with the pharmaceutical industry. Please refer to the original article for a full list of disclosures.

Reference

Lechat B, Appleton S, Melaku YA, et al. Co-morbid insomnia and obstructive sleep apnoea is associated with all-cause mortality. Eur Respir J. Published online December 2, 2021. doi:10.1183/13993003.01958-2021