Elsevier

Sleep Medicine

Volume 34, June 2017, Pages 50-56
Sleep Medicine

Original Article
Study of association of severity of sleep disordered breathing and functional outcome in stroke patients

https://doi.org/10.1016/j.sleep.2017.02.025Get rights and content

Highlights

  • Increased BMI and stroke severity are significant risk factors for sleep disordered breathing in stroke patients.

  • Low apnea hypopnea index (AHI) is predictive of functional independence of stroke patients (based on Barthel index).

  • Increased AHI and low BMI are predictive of poor outcome (based on modified Rankins scale).

Abstract

Objective

Sleep disordered breathing (SDB) is a prevalent yet underrecognized condition that may have major adverse consequences for those affected by it. We performed a prospective observational study to seek a correlation of severity of SDB with the severity of stroke and its functional outcome.

Methods

Patients with history of recent-onset stroke were recruited and underwent overnight polysomnography (PSG) after the acute phase of the stroke was over; for defining hypopneas, 3% and 4% desaturation limits were used, and the apnea−hypopnea index was respectively calculated as AHI3% and AHI4%. Stroke severity was graded using the Scandinavian Stroke Scale. Functional disability and neurological impairment was evaluated six weeks after the PSG using the Barthel Index (<80 = functional dependence; ≥80 = functional independence) and modified Rankins Scale (>2 = poor outcome; ≤2 = good outcome).

Results

A total of 50 patients were enrolled, 30 (60%) with ischemic stroke and 20 (40%) with hemorrhagic strokes. Of the patients, 39 (78%) had an AHI4% of >5/h, 23 (46%) had an AHI4% of >15/h, and 9 (18%) had an AHI4% of >30/h. Multivariate analysis showed that body mass index (odds ratio [OR] = 1.26; 95% confidence interval [CI] = 1.04–1.54, p = 0.019) and Scandinavian Stroke Scale score (stroke severity) (OR = 0.86; 95% CI = 0.76–0.96, p = 0.009) were significant risk factors for predicting SDB (AHI4% > 15) in patients of stroke. When we looked for factors predicting outcomes, only AHI4% (OR = 1.20; 95% CI 1.01–1.43, p value 0.041) was predictive of the functional dependence (based on Barthel Index) of the patient and AHI4% (OR = 1.14; 95% CI 1.03–1.25, p = 0.008) and body mass index (OR = 0.75; 95% CI 0.59–0.96, p = 0.024) were found to be predictive of poor outcome (based on modified Rankins Scale). We obtained similar results, regardless of the hypopnea definition used.

Conclusion

In conclusion, given the high frequency of SDB in stroke patients and its correlation with poor outcome, screening for obstructive sleep apnea in all stroke and transient ischemic attack patients may be warranted.

Introduction

Stroke is a common cause of medical emergency and is a global health problem, affecting individuals in both developed and developing countries. It is a leading cause of disability among adults in India [1]. Its incidence steeply increases with age and, consequently, the burden of stroke may increase in the future because of the aging of the population. It is a frequent cause for long-term disability and has potentially enormous impact on the emotional and socioeconomic outcomes for the patients, their families, and health care services. Also, survivors of stroke have an increased risk of suffering another vascular event, especially another stroke, which is a major source of increased mortality and morbidity [2], [3]. Many stroke patients experience a recurrent stroke within five years [4]. Hence, measures must be implemented to reduce the recurrence risk. During the past few years, efforts have been made to ascertain novel preventable stroke risk factors and to mitigate the residual impact of stroke. Aggressive treatment of risk factors in stroke patients is widely accepted.

In a note published in The Lancet in 1985, it was reported that there was a 40-times higher risk for stroke in snoring inhabitants of the country of Iceland relative to nonsnoring Icelanders [5]. Later, it was hypothesized that snoring is an independent risk factor for stroke [6]. Observations of acute neurological events such as strokes, in the context of sleep disordered breathing (SDB), have revealed a close association. A meta-analysis [7] of the frequency of sleep apnea in stroke patients examined 29 studies comprising 1343 patients and found that SDB was present in 72% of the patients. These studies suggest that SDB may be a modifiable risk factor for stroke.

It is also hypothesized that the severity of SDB may be associated with the severity of stroke and its functional outcome, and that obstructive sleep apnea (OSA) may be a significant predictor of serious adverse outcomes following stroke [8]. Spriggs et al. [9] have shown a clear dose−response relationship between the reported severities of prestroke snoring and mortality six months poststroke. It has been observed that sleep apnea patients have a less favorable functional outcome of stroke and a higher mortality rate [10].

Iranzo et al. [11] studied 50 patients with ischemic stroke during the first night after a stroke, and reported that a high AHI was associated with early neurological deterioration. Turkington et al. [12] suggested a relationship between SDB in the first 24 h poststroke and length of hospital stay, mortality, and a greater dependency of survivors six months later. In contrast, a recent study by Lefevre-Dognin et al. did not demonstrate significant repercussions of SDB on the recovery of poststroke patients [13].

In the present study, we have attempted to seek a correlation of the severity of SDB with the severity of stroke and its functional outcome, and to see if we can identify clinical characteristics in these stroke patients that were associated with poor outcomes, so that further attempts may be directed at correcting these characteristics in the hope of improving the functional outcomes.

Section snippets

Methods

The present prospective observational study was carried out in the Department of Medicine, Vardhman Mahavir Medical College and Safdarjung Hospital (VMMC and SJH), New Delhi. Subjects with a history of recent-onset stroke were recruited on the basis of the following inclusion criteria: acute stroke, confirmed by neuro-imaging; age between 20 and 85 years; and a Glasgow Coma Score (GCS) score of ≥8.

Exclusion criteria were as follows: coma, previous stroke (asymptomatic infarcts discovered at

Results

The study cohort consisted of 50 patents with stroke; 30 (60%) with ischemic stroke and 20 (40%) with hemorrhagic stroke. The mean (±standard deviation [SD]) age of the cohort was 54.6 (±12.49) years, and the mean (±SD) BMI was 28.81 (±5.12) kg/m2. The patient group comprised 31 males (62%) and 19 females (38%). Of these 50 patients, 29 (58%) had hypertension, 21 (42%) had diabetes, 20 (40%) had dyslipidemia, and 7 (14%) had congestive heart failure (CHF). When we assessed the AHI4%, we found

Discussion

Studies have reported a high prevalence of sleep disordered breathing in stroke patients. The initial study by Basetti et al. [18], from Europe, showed that 58% of the patients had an AHI of >10/h and 17% of patients had an AHI >30/h. Turkington et al. [19], from the United Kingdom, also reported that 79% of patients had an AHI of >5/h, 61% had AHI of >10/h, and 45% of patients had an AHI of >15/h. Yan-Fang et al. [20], from China, had also reported that 65% of patients had an AHI of >5/h, 50%

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