Can insomnia increase later stroke risk? Stroke. 2014.


Insomnia is a common problem. For  many this can be a persistent problem. Consequences of insomnia are diverse.Sleep deprivation and insomnia symptoms may alter cardiovascular health through inflammation,endocrine or metabolic dysregulation and increased sym- pathetic nervous activity. Ming-Ping Wu and colleagues asked the question- Would insomnia increase the later risk of stroke?

They  conducted a retrospective cohort study using  the Tainwanese health insurance database which covers the nation ( mandatory) . Data from 5% of all enrolled ( = i million) were analysed in this study.Participants had new onset insomnia ( one hospitalisation or 3 OP visits for this).Those with  insomnia before enrolment, sleep apnoea  and pre existing stroke were  excluded.The main outcome was  first hospitalisation for acute stroke.Study included 21438 subjects with insomnia and 64 314 matched subjects without insomnia .


During the 4-year follow-up period, there were a total of 583 stroke admissions among insomniacs and 962 among non- insomniacs. The incidence rate of stroke was significantly higher (IRR, 1.85; 95% confidence interval [CI], 1.67–2.05) in insomniacs than in non insomniacs. Insomniacs-to-noninsomniacs IRR for stroke decreased as age advanced. The largest IRR for stroke was observed in those aged 18 to 34 years (IRR, 8.06).

Compared with the noninsomnia individuals, those with insomnia were at increased risk of stroke by a magnitude of 54% (adjusted hazard ratio , 1.54; 95% CI, 1.38–1.72) after adjusting for all other covariates.

Conclusion: Presence of insomnia raises the likelihood of subsequent hospitalization for stroke for 4 years. This is more for  transient ischemic attack, followed by unspecified stroke and other forms of stroke. The incidence rate of stroke was ≈8× higher in insomniacs than in noninsomniacs among younger adults.

Comments: How insomnia lead to stroke is unclear. Study might have sampling/selection bias. Control group might have chosen not to seek help for insomnia. Whether health care seeking behaviour is a confounding factor associated both with insomnia and stroke is not known.

Summary of the article: 

Insomnia subtypes and the subsequent risks of strokereport from a nationally representativecohort. Wu MP, Lin HJ, Weng SF, Ho CH, Wang JJ, Hsu YW.

Stroke. 2014 May;45(5):1349-54.

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