Insomnia Associated with Significant Risk for MI, Should be Designated a CV Risk Factor

Persons with insomnia were at a 69% greater risk for myocardial infarction (MI) than those without the sleep disorder, according to results of a large systematic literature review and meta-analysis.

The study also found that among objective measures of insomnia, sleep duration of ≤5 hours conferred the greatest risk of MI and among common comorbidities that persons with diabetes who experience insomnia had twice the risk of MI vs those without insomnia.

The full findings of the research will be presented at the American College of Cardiology’s (ACC) Annual Scientific Session Together with the World Congress of Cardiology, March 4-6, 2023, in New Orleans.

“Insomnia is the most common sleep disorder, but in many ways it’s no longer just an illness, it’s more of a life choice. We just don’t prioritize sleep as much as we should,” said study author Yomna E. Dean, a medical student at Alexandria University in Alexandria, Egypt, in an ACC news release. “Our study showed that people with insomnia are more likely to have a heart attack regardless of age, and heart attacks occurred more often in women with insomnia.”

Currently insomnia is estimated to affect 10% to 30% of American adults, with prevalence greater among women than men and increasing overall. Although “insomnia has been closely associated with cardiovascular disease (CVD) and MI” in existing research, the authors write, this analysis is the largest to date.

Dean and colleagues are hopeful that the study’s pooled data will demonstrate the urgency of considering insomnia as a risk factor for MI.

The investigators conducted a systematic review of the PubMed, Scopus, and Web of Science databases, including only observational controlled studies with data on the incidence of MI among adults with insomnia. The primary outcome was the incidence of MI among those with and without the disorder. Secondary outcomes included sleep duration, age, sex, and comorbidities among both groups.

The review yield was 1226 studies of which 9 were included for analysis. All told, data for 1 184 256 adults (153 881 with insomnia, 1 029 458 controls) were assessed. The final cohort was 43% women and had an average age of 52 years. Insomnia was identified based on ICD diagnostic codes or presence of any of 3 symptoms: difficulty falling asleep, difficulty staying asleep or waking early and not being able to get back to sleep. People with obstructive sleep apnea were not included. The majority of participants (96%) had no history of MI.

FINDINGS

Over a mean follow-up 9 years, MI occurred in 2406 of the 153 881 who had insomnia and in 12 398 of the 1 029 458 participants used as controls. The research team’s pooled analysis found a statistically significant association between insomnia and incidence of MI (relative risk [RR] 1.62, 95% CI, 1.34- 1.95; P<.001) after controlling for risk factors including age, gender, comorbidities, and smoking, according to the study abstract. The authors also report a statistically significant association between sleep duration of ≤5 hours and incidence of MI vs duration of 6 hours (RR 1.38, 95% CI, 1.23-1.54; P<.001)

There was a statistically significant association observed between disorders of initiating and maintaining sleep and MI incidence vs the control group (RR 1.13, 95% CI, 1.04-1.23; P=.003). However, according to findings reported in the abstract, subgroup analysis of non-restorative sleep and daytime dysfunction showed an insignificant association with MI incidence among both groups (RR 1.06, 95% CI, 0.91-1.23; P=.46.)

Analysis of age (<65 and>65 years), follow-up duration (<5 years and >5 years), men and women, and comorbidities (diabetes, hypertension, hyperlipidemia) all showed a statistically significant association with MI in persons with insomnia relative to the control group, the investigators report.

The study had some limitations, note Dean and colleagues, including that most of the studies assessed relied on participants self-reporting on sleep behaviors using questionnaires, although heart attacks were validated by medical reports.

Doma will present Association Between Insomnia and the Incidence of Myocardial Infarction: A Systemic Review and Meta-Analysis, on Monday, March 6, at 11 a.m. CT / 17:00 UTC in Room 357.