29 Jul Sleep Heart Health Study
“Among community based subjects with heart failure, obstructive sleep apnoea (OSA) is noted to be much more common than central sleep apnoea (CSA). This deviates from prior clinic-based investigations of heart failure subjects in which the prevalence of CSA either exceeded or nearly matched that of OSA. Additionally, although those with central sleep apnoea (and/or cheyne stokes respiration) were more likely to have heart failure than those with obstructive sleep apnoea, among subjects with heart failure the prevalence of OSA vastly exceeded CSA and Cheyne-Stokes Respiration.”
Citation
Donovan LM, Kapur VK. Prevalence and characteristics of central compared to obstructive sleep apnea: analyses from the sleep heart health study cohort. SLEEP 2016;39(7):1353–1359.
Introduction
This article looks to determine the prevalence of central sleep apnoea (CSA) in the SHHS cohort (see below for SHHS background) using current definitions and to contrast the clinical characteristics of subjects with CSA to those with obstructive sleep apnoea (OSA) and those with no sleep apnoea. Treatment options may vary for patients with CSA and OSA.
Significance
According to contemporary criteria in the largest sleep cohort available (SHHS), the current work demonstrates CSA prevalence to be 0.9% in adults aged 40 and older. Among community based subjects with heart failure, OSA is much more likely to be the etiology of SDB than CSA.
Background
Central sleep apnoea (CSA) is characterised by recurrent cessation or attenuation of respiration during sleep resulting from a decline or absence of ventilatory effort. Review of the literature suggests that there are two basic mechanisms that trigger central respiratory events: one of which is the post-hyperventilation central apnoea, which may be triggered by a variety of clinical conditions including heart failure (HF), stroke (CVA), atrial fibrillation (AF), renal failure (CKD), and central apnoea secondary to hypoventilation, which has been described with medications (e.g., long acting opiates). In heart failure patients, a specific and unique pattern of periodic central apnoeas may occur. This is known as Cheyne Stokes respiration (CSR) and is characterised by a crescendo / decrescendo pattern of intervening breaths. CSR is associated with increased mortality. Recommendations for the treatment of CSA and CSR have recently changed (see previous newsletter article: Updated Adaptive Servo-Ventilation Recommendations for the 2012 AASM guideline: “The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses”).
The Sleep Heart Health Study (SHHS) is a prospective cohort study designed to investigate obstructive sleep apnoea (OSA) and other sleep-disordered breathing (SDB) as risk factors for the development of cardiovascular disease. The study is designed to enrol 6,600 (recruited 6441 participants) adult participants aged 40 years and older (1995-2006) who will undergo a home polysomnogram to assess the presence of OSA and other SDB. Participants in SHHS have been recruited from cohort studies in progress. Therefore, SHHS adds the assessment of OSA to the protocols of these studies and will use already collected data on the principal risk factors for cardiovascular disease as well as follow-up and outcome information pertaining to cardiovascular disease.
Methods
The current International Classification of Sleep Disorders (ICSD-3) contains 6 definitions of CSA which apply to adult patients. Each of these definitions requires, a central AHI (central apnoeas + central hypopneas/h sleep) ≥ 5 with the central apnoeas and hypopneas accounting for more than 50% of all apnoeas and hypopneas.
The participants or patients data was divided into four groups; no OSA, OSA only, OSA +CSA and CSA only. CSA group (CSA-G) were defined as either or both a central apnoea index (CAI) ≥ 5 and a CAI greater than the obstructive apnoea index (OAI). The Cheyne-Stokes respiration group (CSR) that included subjects meeting criteria for general CSA and periodic breathing (PB). By definition, all individuals with CSR were included in the CSA-G group. In order to create the purest comparison of OSA and CSA, the group with predominant OSA and a possible component of CSA (presence of PB or CAI ≥ 5/h) were not included in our OSA group in the comparisons performed and were referred to as predominant OSA with a CSA component.
Results
Of the 5,804 participants:
- 8% (n = 2,830) had no SDB,
- 6% (n = 2,762) had OSA,
- 7% had predominant OSA with a CSA component (n = 157),
- 9% (n = 55) had CSA-G,
- and 0.4% (n = 24) had CSR.
- Individuals with CSA-G were older (69.1 years) and much more likely to be male (90.9%) than those with OSA
Discussion/conclusion
Further research on contemporary populations with careful attention to central versus obstructive events will be required to evaluate shifting trends in the prevalence of central and obstructive sleep apnoea. Similar to prior work from clinic based samples with older participants and smaller community based populations, the SHHS participants with CSA-G and CSR were:
- older,
- had lower BMI,
- and were more likely to be male than those with OSA.
The known strong associations with ischemic heart disease, heart failure, and atrial fibrillation were also noted. Additionally, although those with CSA-G and CSR were more likely to have heart failure than those with OSA, among subjects with heart failure the prevalence of OSA vastly exceeded CSA-G and CSR. This deviates from prior clinic-based investigations of heart failure subjects in which the prevalence of CSA either exceeded or nearly matched that of OSA. This discrepancy may relate to a lower severity of heart failure in the SHHS sample. Another explanation of the lower frequency of CSA-G and CSR in our heart failure population lies in the relatively high prevalence of women in our heart failure population (43%), as women have much lower risk of CSA.
Our findings would suggest that for the typical heart failure patient in the community, OSA is much more likely to be the etiology of SDB than CSA, and that clinical suspicion and pre-test probabilities should be adjusted accordingly.
http://www.ncbi.nlm.nih.gov/pubmed/9493915 – Sleep Heart Health Study: design, rationale, and methods.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3242685/ – The Treatment of Central Sleep Apnea Syndromes in Adults: Practice Parameters with an Evidence-Based Literature Review and Meta-Analyses