Insomnia and the Risk of Incident Heart Failure: A Population Study
Are self-reported insomnia symptoms associated with heart failure?
Data from the Nord-Trøndelag Health study (HUNT) were used for the present analysis. The HUNT study included a large database of clinical, anthropometric, and socioeconomic information collected during a three-phase population-based health survey in Nord-Trøndelag County, one of the 19 Norwegian counties located in the central part of Norway. Baseline data on insomnia symptoms, including difficulty initiating sleep, difficulty maintaining sleep and having nonrestorative sleep, sociodemographic variables, and health status, including established cardiovascular risk factors, were collected on men and women (20-89 years of age), without heart failure at baseline. Insomnia symptoms were also dichotomized and the highest categories (i.e., having difficulty initiating sleep almost every night, difficulty maintaining sleep almost every night, and having nonrestorative sleep more than once a week) were compared with the rest of the categories. The cohort was followed for incident heart failure from baseline through 2008. The primary outcome of interest was incident heart failure identified at time of hospitalization or by the National Cause of Death Registry.
A total of 54,279 adults were included in the cohort between 1995 and 1997; 1,412 cases of heart failure occurred during a mean follow-up of 11.3 years. Heart failure was more frequent among older participants and in men, and at baseline, participants who developed heart failure during the follow-up were physically less active, consumed less alcohol, and were less educated than other participants. They also had more often diabetes, an unfavorable lipid profile, high blood pressure, and higher body mass index. The prevalence of having difficulties initiating sleep almost every night, having difficulties maintaining sleep almost every night, and having nonrestorative sleep more than once a week were 3.4%, 2.5%, and 8.1%, respectively. Older participants were more likely to have insomnia symptoms, and symptoms were more frequent in women than in men. Insomnia symptoms were associated with cardiovascular risk factors as well as depression, anxiety, and the use of sleep medication/sedatives. There was a dose-dependent association between the number of insomnia symptoms and risk of heart failure. The multi-adjusted hazard ratios (HRs) were 0.96 (0.57-1.61), 1.35 (0.72-2.50), and 4.53 (1.99-10.31) for people with one, two, and three insomnia symptoms, compared with people with none of the symptoms (p for trend = 0.021). Compared with men, women appeared to have a higher relative risk of heart failure associated with nonrestorative sleep and with the cumulative symptoms of insomnia (HR, 6.81; 95% confidence interval [CI], 2.68-17.29 for women with three insomnia symptoms vs. HR, 2.04; 95% CI, 0.28-14.63 for men with three insomnia symptoms).
The investigators concluded that insomnia was associated with an increased risk of incident heart failure.
These data add to our understanding of the importance of sleep for cardiovascular health. However, as the authors point out, a major question remains—whether treating insomnia would reduce the risk for heart failure.
Keywords: Depression, Sleep Initiation and Maintenance Disorders, Body Mass Index, Norway, Self Report, Heart Failure, Hypnotics and Sedatives, Diabetes Mellitus
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