07 September 2012

Cardiovascular Mortality Risk In Obstructive Sleep Apnea (OSA) Increases With Age

Sleep apnea is a disorder where the affected person experiences episodes where breathing stops or becomes shallow while sleeping. Apnea is the term for each pause in breathing. The apnea can vary from a few seconds to a few minutes.

AHI or Apnea-Hypopnea Index (AHI) is a measurement of how many times an apnea episode occurs in one hour. An AHI of 5 below is considered normal. AN AHI of 30 or above is categorized as severe since it would mean that on average, the patient stops breating every two minutes.

There are three forms of sleep apnea; central (CSA), obstructive (OSA), and complex or mixed sleep apnea (a combination of CSA and OSA).

Central sleep apnea occures when breating is interrupted because of lack of effort in breathing. Obstructive sleep apnea involves a physical blockage which causes the airflow to stop, snoring is usually a symptom of OSA.

The goal in treating sleep apnea is to keep the air passage open and allow the patient to breath easily while sleeping. For OSA, a CPAP device is used to assist in breathing. It is a tight fitting face mask that is attached to a machine that assists in breathing. CPAP stands for Continuous positive airway pressure (CPAP).

OSA increases cardiovascular mortality in the elderly

Untreated severe obstructive sleep apnea (OSA) is associated with an increased risk of cardiovascular mortality in the elderly, and adequate treatment with continuous positive airway pressure (CPAP) may significantly reduce this risk, according to a new study from researchers in Spain.

"Although the link between OSA and cardiovascular mortality is well established in younger patients, evidence on this relationship in the elderly has been conflicting," said lead author Miguel Ángel Martínez-García, MD, of La Fe University and Polytechnic Hospital in Valencia, Spain. "In our study of 939 elderly patients, severe OSA not treated with CPAP was associated with an increased risk of cardiovascular mortality especially from stroke and heart failure, and CPAP treatment reduced this excess of cardiovascular mortality to levels similar to those seen in patients without OSA."

The findings were published online ahead of print publication in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine.

Video: Obstructive Sleep Apnea

All subjects in this prospective, observational study were 65 years of age or older. Median follow-up was 69 months. Sleep studies were conducted with either full standard polysomnography or respiratory polygraphy following Spanish guidelines. OSA was defined as mild-to-moderate (apnea-hypopnea index [AHI] 15-29) or severe (AHI ≥30). Patients with AHI less than 15 acted as controls. CPAP use ≥4 hours daily was considered as good adherence to treatment.

Compared with the control group, the adjusted hazard ratios for cardiovascular mortality were 2.25 (CI, 1.41 to 3.61) for patients with untreated severe OSA, 0.93 (CI, 0.46 to 1.89) for patients treated with CPAP and 1.38 (CI, 0.73 to 2.64) for patients with untreated mild-to-moderate OSA. Similar results were observed among the subgroup of patients ≥75 years of age. Among patients who initiated CPAP treatment, compliance was independently associated with a reduced risk of cardiovascular mortality.

The study had a few limitations, including that the study was not randomized, the reduced statistical power in the subgroup analyses, and the use of respiratory polygraphy to diagnose OSA in a number of patients. Strengths included being the large study size including exclusively elderly patients and the long follow-up.

"This is the first large-scale study to examine the impact of OSA on cardiovascular mortality in a series including exclusively elderly patients and assess the effectiveness of CPAP treatment in reducing this risk," said Dr. Martínez-García. "Our finding that adequate CPAP treatment is associated with significant reductions in cardiovascular mortality in patients with OSA has important implications, especially given the increasing elderly population."


American Thoracic Society
American Journal of Respiratory and Critical Care Medicine
La Fe University and Polytechnic Hospital (Spanish site)
Sleep Apnea: A High Risk Factor in Silent Stroke and Small Brain Lesions
Breathing Treatment for Sleep Apnea May Help Protect Against Heart Failure
Continuous Sleep Favorable In Long Term Memory Consolidation and Enhancement
7 Hours is Optimal Sleep For High School Students Before A Test
Lucid Dreaming - Weekend Video: Waking Life
Weekend Fun: 16 Things You Didn't Know About Sleep