Obstructive sleep apnea: in search of precision

MicroRNA Profile of Cardiovascular Risk in Patients with Obstructive Sleep Apnea

BACKGROUND

Obstructive sleep apnea (OSA) is a common disease caused by repeated episodes of collapse of the upper airway during sleep and is associated with the development of cardiovascular disease (CVD). However, there is high heterogeneity in the impact of OSA on patients. Until now, the profile of OSA patients at risk of developing CVD has not been defined, including the measurable variables that could be used to predict the CVD risk of a patient with OSA.

OBJECTIVE

The aim of this study was to identify the microRNA (mi-RNA) profile associated with CVD in patients with OSA.

METHOD

This is an observational, cross-sectional study that included 132 male patients. Three groups were defined as OSA patients, OSA patients with hypertension, and OSA patients who developed a major cardiovascular event. Polysomnography and ambulatory blood pressure measurements were performed. The expression profiling of 188 miRNAs in plasma was performed in 21 subjects (matched by BMI and age) by the TaqMan low density array (TLDA). miRNAs differentially expressed in the different subgroups of patients and miRNAs that correlated with the cardiovascular risk SCORE were selected for validation by RT-qPCR in the 111 remaining patients.

RESULTS

From the TLDA analysis, 7 miRNAs were selected for validation. Differential expression was not confirmed in any of the miRNAs. miR-143 was associated with nocturnal systolic blood pressure. miR-107 correlated with 24-h blood pressure parameters and with nocturnal hypertension. miR-486 was associated with the cardiovascular risk SCORE.

CONCLUSIONS

The circulating profile of miRNAs does not seem to be different in any of the subgroups of patients with OSA and different cardiovascular risk factors. Nevertheless, miR-107 and miR-143 are associated with specific blood pressure parameters in patients with OSA and miR-486 is associated with the cardiovascular risk SCORE.

Technologic advances in the assessment and management of obstructive sleep apnoea beyond the apnoea-hypopnoea index: a narrative review

Obstructive sleep apnoea (OSA) is a growing and serious worldwide health problem with significant health and socioeconomic consequences. Current diagnostic testing strategies are limited by cost, access to resources and over reliance on one measure, namely the apnoea-hypopnoea frequency per hour (AHI). Recent evidence supports moving away from the AHI as the principle measure of OSA severity towards a more personalised approach to OSA diagnosis and treatment that includes phenotypic and biological traits. Novel advances in technology include the use of signals such as heart rate variability (HRV), oximetry and peripheral arterial tonometry (PAT) as alternative or additional measures. Ubiquitous use of smartphones and developments in wearable technology have also led to increased availability of applications and devices to facilitate home screening of at-risk populations, although current evidence indicates relatively poor accuracy in comparison with the traditional gold standard polysomnography (PSG). In this review, we evaluate the current strategies for diagnosing OSA in the context of their limitations, potential physiological targets as alternatives to AHI and the role of novel technology in OSA. We also evaluate the current evidence for using newer technologies in OSA diagnosis, the physiological targets such as smartphone applications and wearable technology. Future developments in OSA diagnosis and assessment will likely focus increasingly on systemic effects of sleep disordered breathing (SDB) such as changes in nocturnal oxygen and blood pressure (BP); and may also include other factors such as circulating biomarkers. These developments will likely require a re-evaluation of the diagnostic and grading criteria for clinically significant OSA.

The Impact of Telehealth on the Organization of the Health System and Integrated Care

Sleep medicine is a rapidly developing field of medicine that is well-suited to initiatives such as Telehealth to provide safe, effective clinical care to an expanding group of patients. The increasing prevalence of sleep disorders has resulted in long waiting lists and lack of specialist availability. Telemedicine has potential to facilitate a move toward an integrated care model, which involves professionals from different disciplines and different organizations working together in a team-oriented way toward a shared goal of delivering all of a person's care requirements. Issues around consumer health technology and nonphysician sleep providers are discussed further in the article.

Circulating microRNA profile as a potential biomarker for obstructive sleep apnea diagnosis

Evaluation of microRNAs (miRNAs) could allow characterization of the obstructive sleep apnea (OSA) and help diagnose it more accurately. We aimed to examine circulating miRNA profiles to establish the differences between non-OSA and OSA patients. Additionally, we aimed to analyse the effect of continuous positive airway pressure (CPAP) treatment on the miRNA profile. This observational, longitudinal study included 230 subjects referred to the Sleep Unit due to suspected OSA. Expression profiling of 188 miRNAs in plasma was performed in 27 subjects by TaqMan-Low-Density-Array. OSA-related miRNAs were selected for validation by RT-qPCR in 203 patients. Prediction models were built to discriminate between non-OSA and OSA: 1) NoSAS-score, 2) differentially expressed miRNAs, and 3) combination of NoSAS-score plus miRNAs. The differentially expressed miRNAs were measured after 6 months of follow-up. From the 14 miRNAs selected for validation, 6 were confirmed to be differentially expressed. The areas under the curve were 0.73 for the NoSAS-score, 0.81 for the miRNAs and 0.86 for the combination. After 6 months of CPAP treatment, miRNA levels in the OSA group seem to approximate to non-OSA levels. A cluster of miRNAs was identified to differentiate between non-OSA and OSA patients. CPAP treatment was associated with changes in the circulating miRNA profile.

Identification and validation of circulating miRNAs as endogenous controls in obstructive sleep apnea

microRNAs (miRNAs) are non-coding RNAs highly relevant as biomarkers for disease. A seminal study that explored the role of miRNAs in obstructive sleep apnea syndrome (OSA) demonstrated their usefulness in clinical management. Nevertheless, the miRNAs that may act as endogenous controls (ECs) have not yet been established. The identification of ECs would contribute to the standardization of these biomarkers in OSA. The objective of the study is to identify miRNAs that can be used as ECs in OSA. We evaluated 100 patients divided into two different cohorts: a learning cohort of 10 non-OSA and 30 OSA patients, and a validation cohort (20 non-OSA and 40 OSA patients). In the learning cohort, a profile of 188 miRNAs was determined in plasma by TaqMan Low Density Array. The best EC candidates were identified by mean center+SD normalization and concordance correlation restricted normalization. The results were validated using NormFinder and geNorm to assess the stability of those ECs. Eight miRNAs were identified as EC candidates. The combination miRNA-106a/miRNA-186 was identified as the most stable among all candidates. We identified a set of ECs to be used in the determination of circulating miRNA in OSA that may contribute to the homogeneity of results.