CPAP May Reduce Excess Mortality in Stroke Patients With Sleep Apnea

Susan Jeffrey

July 20, 2009

July 20, 2009 — A new study confirms that stroke patients who have moderate to severe obstructive sleep apnea (OSA) have a higher mortality risk than those without this condition and suggests that the successful use of continuous positive airway pressure (CPAP) therapy can reduce this excess risk.

Over 5 years of follow-up in this observational study, stroke patients who did not tolerate CPAP had a higher mortality risk than either those without OSA or those who had OSA and were able to adhere to treatment.

Due to "less than optimal" compliance with CPAP therapy, the authors conclude, "there is a need for more studies that focus on improving the adherence to and tolerance of CPAP treatment in these patients."

The report, with first author Miguel Angel Martinez-Garcia, MD, from the Unidad de Neumología at the Hospital General de Requena in Valencia, Spain, is published in the July 1 issue of the American Journal of Respiratory and Critical Care Medicine.

Modifiable Risk

Survivors of an ischemic stroke are at increased risk of suffering another vascular event, particularly stroke, which is a major source of mortality and morbidity, the authors write. Rates of 30-day mortality after a first stroke are estimated to be between 10% and 17%, they note, and 5-year survival is about 40%.

Although a number of risk factors for stroke — among them age, race, sex, and family history of cardiovascular disease — are nonmodifiable, efforts are underway to identify new risk factors that may be modifiable, they write. Among these is obstructive sleep apnea, which, it has been suggested, is itself an independent risk factor for stroke.

In this prospective study, Dr. Martinez-Garcia and colleagues followed a cohort of stroke patients seen consecutively at their institution. Sleep studies were performed in all patients who survived to at least 2 months after the acute stroke, and CPAP therapy was offered to all of those who were found to have moderate to severe OSA.

Of 223 patients admitted for stroke, a sleep study was performed in 166. Of these, 31 had an apnea-hypopnea index (AHI) of less than 10, 39 had an AHI between 10 and 19, and 96 had an AHI of 20 or greater, indicating moderate to severe OSA. CPAP was offered to this latter group of patients.

Patients were then followed at their outpatient clinic at 1, 3, and 6 months, and every 6 months thereafter out to 5 years. Mortality data were taken from their database and from official death certificates.

Over time, those with an AHI of 20 or greater who did not tolerate CPAP had an increased adjusted risk for mortality over either those with an AHI of less than 20(hazard ratio [HR], 2.69; 95% CI, 1.32 – 5.61) or those with moderate to severe OSA who were able to tolerate CPAP therapy (HR, 1.53; 95% CI, 1.01 – 2.49; P = .04).

No differences in mortality were seen among patients without OSA, those with mild OSA, or those who tolerated CPAP therapy, they note.

Low Adherence a "Constant"

One limitation of their study is the low adherence to CPAP therapy, with only about 30% using the therapy over the 5 years of follow-up, the authors write. "This limitation is a constant in all studies on this topic because of the great difficulty in treating patients who have had a stroke with CPAP, especially those with chronic sequelae, and because of the lack of somnolence in most cases," they note.

"Nevertheless, our study attained the highest percentage of patients tolerating long-term CPAP therapy among the published studies on the stable phase of neurological events," they conclude. "We think that we achieved this percentage because of our efforts to resolve all problems in follow-up and to educate our patients, families, and general practitioners in CPAP therapy."

The study was supported by a grant from the Sociedad Valenciana de Neumologia. The authors have disclosed no relevant financial relationships.

Am J Respir Crit Care Med. 2009;180:36-41. Abstract

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