The prospective study included 1,068 consecutive patients an average of 16 months after a heart attack and/or a procedure to open blocked arteries (stent implantation or bypass surgery). Data on insomnia, risk factors for repeat heart events, and co-existing conditions were collected at baseline.
Participants completed the Bergen Insomnia Scale questionnaire which is based on the diagnostic criteria for insomnia.3 Six questions cover the ability to fall asleep and stay asleep, waking up prematurely, feeling inadequately rested, tiredness during the day that affects ability to function at work or socially, and being dissatisfied with sleep.
The risk factors included C-reactive protein (a marker of inflammation), smoking status, low-density lipoprotein (LDL) cholesterol, diabetes, physical activity, waist circumference, and systolic blood pressure. The co-existing conditions were stroke, transient ischemic attack, peripheral artery disease, and kidney failure.
Patients were followed for the primary composite endpoint of major adverse cardiovascular events (MACE), defined as cardiovascular death, hospitalization due to myocardial infarction, revascularisation, stroke or heart failure. Outcome data were obtained from hospital records.
Approximately one in five participants (21%) were women. At baseline, the average age of patients was 62 years, almost half (45%) had insomnia and 24% had used sleep medication in the past week. During an average follow-up of 4.2 years, a total of 364 MACE occurred in 225 patients.
Compared to those without insomnia, the relative risk of recurrent MACE in patients with insomnia was 1.62 after adjusting for age and sex, 1.49 after additional adjustment for coronary risk factors, and 1.48 after also adjusting for co-existing conditions. The association between insomnia and recurrent MACE remained significant when symptoms of anxiety and depression were also adjusted for, with a relative risk of 1.41.
Insomnia accounted for 16% of recurrent MACE in attributable risk fraction analyses, being third in importance after smoking (27%) and low physical activity (21%). Mr. Frojd said: “This means that 16% of recurrent major adverse cardiovascular events might have been avoided if none of the participants had insomnia.”
He concluded: “Further research is needed to examine whether insomnia treatments such as cognitive behavioral therapy and digital applications are effective in this patient group.”
Source: Eurekalert
