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Sleep Apnea and Stroke

5th Edition
2014 UPDATE
December 2014

The Canadian Stroke Best Practice Recommendations for the Secondary Prevention of Stroke, 5th Edition 2014 module is published in the International Journal of Stroke (IJS) (Online Open‑Access available December 2014; Printed Journal scheduled for April 2015).

To access the specific recommendations for Sleep Apnea and Stroke and all other sections of the Secondary Prevention of Stroke module, please click on this URL which will take you to the recommendations online in the IJS:  http://onlinelibrary.wiley.com/doi/10.1111/ijs.12439/full. For the French version of these recommendations, open the appendix at this link : http://onlinelibrary.wiley.com/store/10.1111/ijs.12439/asset/supinfo/ijs12439-sup-0001-si.pdf?v=1&s=b0ed4fff1d7fc435cf4e2a83ccbcbffbdad767de.

All other supporting information, including performance measures, implementation resources, evidence summaries and references, remain available through www.strokebestpractices.ca, and not through the IJS.  Please click on the appropriate sections below for this additional content.

Rationale

Sleep apnea is an emerging area of concern in stroke management. Sleep Disorders are an under recognized problem that predispose people to stroke occurrence and recurrence. Sleep apnea is a modifiable risk factor that can be treated quickly to alleviate the associated risk of stroke. Although there is a lack of randomized controlled trials, several observational studies have demonstrated that people with obstructive sleep apnea are 1.6 to 2.7 times more likely to experience a stroke. Treating patients with obstructive sleep apnea and stroke with continuous positive airway pressure has been shown to have positive effects on outcomes in the post-stroke setting. Patients with untreated sleep apnea have demonstrated poorer outcomes and increased mortality rates.

System Implications
  • Implementation of protocols for assessment of sleep disturbances or risk factors for sleep apnea in stroke patients
  • Implementation of criteria to prioritize appropriate access to sleep specialists and sleep study labs as required, especially in under-resourced regions
  • Regional service capacity and clearly communicated access criteria for specialized sleep medicine services
  • Resources and opportunities for education on sleep apnea and correct use of screening and assessment tools for healthcare professionals
  • Development of patient and family education resources on the awareness of sleep apnea as a risk factor pre and post stroke, and the importance of screening and treatment adherence.
Performance Measures
  1. Proportion of patients presenting to hospital with stroke or TIA who have a history of confirmed sleep apnea.
  2. Proportion of patients with stroke or TIA who are screened for sleep apnea symptoms before discharge from acute care, during inpatient or outpatient stroke rehabilitation, and/or during stroke prevention follow-up visits.
  3. Proportion of patients who are screened and referred for sleep studies following a stroke or TIA.
  4. Proportion of patients referred for sleep studies following a stroke or TIA who receive a confirmed diagnosis of sleep apnea.
  5. Proportion of stroke and TIA patients with confirmed sleep apnea with recurrent stroke or TIA at one year and 5 years following index stroke or TIA.
  6. Quality of life for patients with sleep apnea and their family members (measured at intervals to monitor changes over time with treatment).
  7. Sustained weight loss for overweight or obese patients with stroke and sleep apnea at regular intervals (1 year, 2 years etc.) Following achievement of target weight loss.

Measurement Notes

  • Data for these indicators will be in health professional notes and assessment sections of individual charts, and should be added to electronic health records.
Implementation Resources and Knowledge Transfer Tools

Health Care Provider Information

Patient Information

Summary of the Evidence, Evidence Tables and References

Sleep Apnea and Stroke Evidence Tables and Reference List

Obstructive sleep apnea (OSA) is both a risk factor for stroke and can occur as a consequence of stroke. OSA is the most common type of sleep disordered breathing associated with stroke and the level of severity is defined by the number of apneas/hypopneas a subject experiences per hour of sleep (apnea/hypopnea index, AHI). Mild OSA is often defined as >5 AHI and severe OSA often defined as >30 AHI. A systematic review and meta-analysis by Johnson & Johnson (2010) (29 studies; n=2343) reported a prevalence of OSA in patients with stroke according to AHI. Seventy-two percent of patients had an AHI > 5, while 29% had an AHI > 30 (Johnson & Johnson 2010). Prevalence rates for OSA have been found to vary between 17% - 76%, depending on the study’s sample characteristics and the definition of sleep apnea used. In the acute phase of stroke, Dziewas et al. (2005) reported that 59% of participants were found to have ‘relevant’ sleep apnea (AHI ≥10). Similarly, Iranzo et al. (2002) reported that 62% of patients with ischemic stroke in their study had sleep apnea (AHI ≥10). During active rehabilitation, Aaronson et al. (2012) reported a sleep apnea prevalence rate of 46% (AHI ≥15).

Patients experiencing OSA are at an increased risk for the occurrence of stroke. A cross-sectional study by Artz et al. (2005) assessed 1475 individuals with sleep apnea and found that those patients with severe apnea (AHI≥20) were reported to have a greater odds of stroke, controlling for age, sex, body mass index, alcohol use, and smoking status (OR= 4.33, 95% CI 1.32 to 14.24, p=0.02) than those patients with no/mild apnea (AHI<5). The results remained statistically significant even after controlling for the presence of hypertension and diabetes. Two long-term cohort studies captured the occurrence of stroke for patients reported to have sleep apnea at a baseline assessment. With a sample size of 5422 and a median study duration of 8.7 years, Redline and colleagues (2010) found that there was an increased risk of stroke for those patients with baseline sleep apnea, and the odds were higher for men compared to women (OR= 2.26, 95% CI 1.45 to 3.52 vs. OR 1.65, 95% CI 1.45 to 3.52). Valham et al. (2008) conducted a similar study with a cohort of 392 patients, following patients for the occurrence of stroke within 10 years. Compared to those without sleep apnea at baseline, participants with sleep apnea were significantly more likely to experience a stroke during the 10-year study period (38% vs 9%, p<0.001).

Factors reported to be associated with significantly increased risk of OSA include a hemorrhagic stroke (vs. ischemic stroke, adjusted OR=12.06, 95% CI 1.42 to 102.74)(Cadihac et al. 2005), a high level of stroke severity (adjusted OR=4.15, 95% CI 1.05 to 16.38) (Cadihac et al. 2005), a recurrent stroke (p<0.05) (Dziewas et al. 2005), early neurological worsening (p<0.001) (Iranzo et al. 2002), and sleep related stroke onset (p<0.001) (Iranzo et al. 2002). Additionally, drug resistant hypertension and atrial fibrillation have been highlighted as being associated with a higher risk of experiencing sleep apnea. The odds of a patient with drug resistant hypertension experiencing sleep apnea is 2.46 times greater than a patient who does not have drug-resistant hypertension (OR=2.46, 95% CI 1.03 to 5.88, p< 0.05)(Demede et al. 2011). The severity of AHI was also greater in a drug-resistant hypertensive group compared to a group with controlled hypertension (AHI 43.0 vs. 18.1, p=0.02) (Cadihac et al. 2005). Currently, there is limited evidence assessing the relationship between atrial fibrillation, sleep apnea and stroke, however, in a non-stroke specific study, Braga and colleagues (2009) found that patients with atrial fibrillation had higher rates of sleep apnea compared to a control group (81.6% vs. 60%, p=0.03). Similarly, Abe and colleagues (2010) identified associations between paroxysmal atrial fibrillation incidence and obstructive sleep apnea (p=0.009).

Interventions for the treatment and management of sleep apnea have been evaluated in several non-stroke specific Cochrane reviews. The use of drug therapy (Mason et al. 2013), oral appliances (Lim et al. 2006), surgery (Sundaram et al. 2009), weight loss, sleep hygiene and exercise (Shneerson et al. 2009), and continuous positive airway pressure (CPAP) (Giles et al. 2006) have been evaluated. The most promising intervention to date has been CPAP, with others reporting no or limited evidence. CPAP has been found to significantly reduce the occurrences of Paroxysmal Atrial Fibrillation (P < 0.001)(Kaneko et al. 2003), improve sleep-related symptoms (Broadley et al. 2007; Patel et al. 2003; Wessendorf et al. 2001)and may prevent the occurrence of new vascular events (Bravata et al. 2010; Martinez-Garcia et al. 2005). CPAP is the most widely studied intervention for the treatment of sleep apnea.

For patients with stroke, Brown et al. (2013) conducted a randomized controlled trial (RCT) to assess the use of CPAP for 32 acute ischemic stroke patients with predominately obstructive sleep apnea (defined as AHI ≥5, assessed within 7 days of stroke onset). Participants were randomized to receive active CPAP (n=15) or sham CPAP (n=17). Between group comparisons were not significant for any of the measured outcomes except depression symptom severity (mean PHQ-9, 5 vs. 2, p<0.05) (Brown et al. 2013). CPAP has also been found to improve vascular factors, with drug-resistant hypertensive patients experiencing a statistically significant reduction in daytime diastolic blood pressure (-6.12mmHg, 95% CI -1.45 to -10.82, p=0.004), 24-hour diastolic blood pressure (-6.98mmHg, 95% CI -1.86 to -12.1, p=0.009) and 24-hour systolic blood pressure   (-9.71mmHg, 95% CI -0.20 to -19.22, p=0.046) (Martinez-Garcia al. 2005). Another two RCTs assessing CPAP reported improvements in National Institutes of Stroke Scale (NIHSS) and Rankin scale scores for the intervention group compared to controls (Bravata et al. 2011; Parra et al. 2011). Bravata and colleagues (2011) found a median improvement in NIHSS scores for the intervention group compared to the control group of -3.0 vs. -1.0 (p=0.03), while Parra et al. (2011) reported increased odds of improved Rankin Scale scores from baseline to 1-month follow-up (OR= 7.8, 95% CI 1.7 to 39.8, p=0.02). Although CPAP was not found to reduce the cardiovascular mortality rate (0% vs 4.3%, p>0.05) or the 24-month cardiovascular event-free survival rate (87.7% vs. 88.4%, p>0.05), the mean time to cardiovascular event occurrence was significantly longer for patients in the CPAP group compared to those in the control group (14.9 vs. 7.9 months, p=0.04) (Parra et al. 2011). The greatest improvements in outcomes have been found when CPAP is started within 48 hours of stroke onset (Bravata et al. 2011). Despite evidence for the success of CPAP, a qualitative systematic review by Tomfohr et al. (2012) commented on concerns of the poor levels of compliance for patients receiving CPAP therapy.

The evidence in support of interventions other than CPAP is limited. Positional therapy was evaluated in a RCT by Svatikova and colleagues (2011), finding that the use of positional therapy to treat sleep apnea in an ischemic stroke population reduced the absolute percentage of time spent in a supine position while sleeping by 36% (95% CI 18% to 55%, p<0.001) and reduced AHI by a relative 19.5% (95% CI 4.9% to 31.9%, p= 0.011.