Multiple sleep-wake disturbances after stroke predict an increased risk of cardio-cerebrovascular events or death: A prospective cohort study.

Abstract

Contradictory evidence on the impact of single sleep-wake-disturbances (SWD), such as sleep-disorderd breating (SDB) or insomnia, in patients with stroke, on the risk of subsequent cardio- and cerebrovascular events (CCE) and death, exists. Very recent studies in the general population suggest that the presence of multiple SWD increases cardio-cerebrovascular risk. Hence, the aim of this study was to asssess whether a novel score capturing the burden of multiple SWD, a so called "sleep burden index", is predictive for subsequent CCE including death in a prospectively followed cohort of stroke patients. Patients with acute ischemic stroke or transient ischemic attack (TIA) were prospectively recruited. Four SWD were analyzed: (i) SDB with respirography; (ii) insomnia (defined using the insomnia severity index [ISI]); (iii) restless legs syndrome (RLS; defined using the International RLS Study Group rating scale); and (iv) self-estimated sleep duration at 1 and 3 months. A "sleep burden index", calculated using the mean of z-transformed values from assessments of these four SWD, was created. The occurrence of CCE was recorded over a mean ± standard deviation (SD) follow-up of 3.2 ± 0.3 years. We assessed 437 patients (87% ischemic stroke, 13% TIA, 64% males) with a mean ± SD age of 65.1 ± 13.0 years. SDB (respiratory event index ≥ 5/h) was present in 66.2% of these patients. Insomnia (ISI ≥ 10), RLS and extreme sleep duration affected 26.2%, 6.4% and 13.7% of the patients 3 months post-stroke. Seventy out of the 437 patients (16%) had at least one CCE during the follow-up. The sleep burden index was associated with a higher risk for subsequent CCE, including death (odds ratio 1.80 per index unit, 95% confidence interval 1.19-2.72; p=0.0056). The presence of multiple SWDs constitutes a risk for subsequent CCE (including death) within the first 3 years following stroke. Larger systematic studies should assess the utility of the sleep burden index for patients' risk stratification in clinical practice.