Objective:
To describe the relationship between sleep problems, measured by the Medical Outcomes Sleep scale (MOS) at baseline, in ischemic stroke and TIA (IS/TIA) patients and the likelihood of having a recurrent event, leading to vascular death.
Background:
Among IS/TIA patients, there is increased risk for recurrent vascular events, including stroke, MI and vascular death. While history of stroke is a major predictor of recurrent events, there may be unidentified factors in play. Sleep quality may predict recurrent vascular events, but little is known about the relationship between sleep and recurrent events in IS/TIA patients.
Methods:
The Stroke Warning Information and Faster Treatment (SWIFT) Study is an NINDS SPOTRIAS funded randomized trial to study the effect of culturally appropriate, interactive education on stroke knowledge and time to arrival after IS/TIA. Sleep problems and recurrent event information were collected among consentable IS/TIA patients. Cox proportional hazards models were used to describe relationships between sleep and recurrent vascular events in IS/TIA patients. The MOS, a 12 item sleep assessment, measures 6 dimensions of sleep: initiation, maintenance, quantity, adequacy, somnolence and respiratory impairment.
Results:
Over 5 years, the SWIFT study cohort of 1198 [77% IS; 23% TIA] patients were prospectively enrolled. This cohort was 50% female; 50% Hispanic, 31% White and 18% Black, with a mean NIHSS of 3.2 [SD ±3.8]. 750 subjects completed the MOS scale at baseline. In a multivariate analysis, after adjusting for demographics and vascular risk factors: gender, age, race ethnicity, NIHSS, stroke history, qualifying event type, hypertension, diabetes, smoking and family stroke history, longer sleep initiation is associated with combined outcome of IS/TIA, MI and vascular death [p=0.1, HR=1.09]. Significant predictors of vascular death included: trouble falling asleep (initiation) [p=0.05, HR=1.15]; not ‘getting enough sleep to feel rested’ and not ‘getting the amount of sleep you need’ (adequacy) [p=0.06, HR=1.18 and p=0.03, HR=1.18, respectively]; shortness of breath or headache upon waking (respiratory impairment) [p=0.003, HR=1.33]; restless sleep [p=0.07, HR=1.15] and waking at night with trouble resuming sleep [p=0.004, HR=1.23] (maintenance); daytime drowsiness [p=0.05, HR=1.18] and trouble staying awake [p=0.01, HR=1.25] (somnolence); and taking naps (quantity) [p=0.03, HR=1.22].
Conclusions:
Sleep problems represent diverse, modifiable risk factors for secondary vascular events, particularly vascular death. Exploring sleep dimensions may yield crucial information for reduction of secondary vascular events in IS/TIA patients. Further investigation is needed to fully understand the effects of sleep on secondary vascular event incidence.
Estimating the ratio of multivariate recurrent event rates with application to a blood transfusion study
