The medical cost of undiagnosed sleep apnea

Clinical consequences and economic costs of untreated obstructive sleep apnea syndrome

Objective

To provide an overview of the healthcare and societal consequences and costs of untreated obstructive sleep apnea syndrome.

Data sources

PubMed database for English-language studies with no start date restrictions and with an end date of September 2014.

Methods

A comprehensive literature review was performed to identify all studies that discussed the physiologic, clinical and societal consequences of obstructive sleep apnea syndrome as well as the costs associated with these consequences. There were 106 studies that formed the basis of this analysis.

Conclusions

Undiagnosed and untreated obstructive sleep apnea syndrome can lead to abnormal physiology that can have serious implications including increased cardiovascular disease, stroke, metabolic disease, excessive daytime sleepiness, work-place errors, traffic accidents and death. These consequences result in significant economic burden. Both, the health and societal consequences and their costs can be decreased with identification and treatment of sleep apnea.

Implications for practice

Treatment of obstructive sleep apnea syndrome, despite its consequences, is limited by lack of diagnosis, poor patient acceptance, lack of access to effective therapies, and lack of a variety of effective therapies. Newer modes of therapy that are effective, cost efficient and more accepted by patients need to be developed.

Healthcare Service Utilization by Patients with Obstructive Sleep Apnea: A Population-Based Study

OBJECTIVE

Although obstructive sleep apnea (OSA) is not a life-threatening disease, very few studies have compared differences in healthcare service utilization between patients with and those without OSA in an Asian population according to different age groups. This study attempted to investigate differences in healthcare service utilization between patients with and those without OSA in different age groups in Taiwan.

METHODS

Sampled subjects and data on their health service utilization were retrieved from the Taiwan Longitudinal Health Insurance Database 2005. We included 568 patients with OSA and 2840 subjects without OSA. Each subject was followed for a 1-year period to evaluate their healthcare resource utilization. Wilcoxon-Mann-Whitney tests were performed to compare differences in healthcare utilization between patients with and those without OSA during the 1-year follow-up period.

RESULTS

As to all healthcare service utilization, patients with OSA had significantly more outpatient visits (30.3 vs. 18.6), outpatient costs (US$1231.2 vs. US$764.8), inpatient days (1.8 vs. 1.2), inpatient costs (US$563.6 vs. US$276.7), and total costs (US$1794.8 vs. US$1041.5) than comparison subjects during the 1-year follow-up period. Moreover, patients with OSA aged 40~49 and 50~59 years respectively incurred 2.11- and 2.02-fold higher total costs compared to patients without OSA. However, patients with OSA aged over 70 years did not have higher total costs compared to those without OSA.

CONCLUSIONS

This study found that patients with OSA had greater healthcare service utilization than those without OSA. Additionally, patients with OSA in the 40~49- and 50~59-year age groups had about 2-fold higher total costs of healthcare services than those without OSA.

Automated detection of sleep apnea in infants using minimally invasive sensors

To address the difficult and necessity of early detection of sleep apnea hypopnea syndrome in infants, we present a study into the effectiveness of pulse oximetry as a minimally invasive means of automated diagnosis of sleep apnea in infants. Overnight polysomnogram data from 328 infants were used to extract time-domain based oximetry features and scored arousal data for each subject. These records were then used to determine apnea events and to train a classifier model based on linear discriminants. Performance of the classifier was evaluated using a leave-one-out cross-validation scheme and an accuracy of 68% was achieved, with a specificity of 68.6% and a sensitivity of 55.9%.

Comparison of a simple obstructive sleep apnea screening device with standard in-laboratory polysomnography

BACKGROUND

Obstructive sleep apnea (OSA) is a common underdiagnosed sleep disorder. Various strategies have been employed to easily screen for OSA. The ApneaStrip® (AS - S.L.P. Ltd, Tel Aviv, Israel) is an FDA approved OSA screening device applied to the upper lip at home. We evaluated the performance of this device against simultaneous in-laboratory polysomnography (PSG) in a group of well-characterized OSA patients.

METHODS

Diagnostic PSG was performed in 56 patients (29 M, 37 F; age 48.9 ± 14.6 years; body mass index [BMI] 37.5 ± 9.0 kg/m(2); apnea-hypopnea index-events/h-[AHI] 32.8 ± 22.9). The AS was applied and positioned to detect nasal and oral airflow. The AS gives a "positive" result for AHI ≥ 15. We examined the sensitivity and specificity of the AS against three thresholds derived from PSG: AHI ≥ 5, AHI ≥ 15 (company recommendation), and AHI ≥ 30.

RESULTS

For PSG AHI ≥ 15, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the AS were 80, 54.5, 87.8, and 40 %, respectively. For PSG AHI ≥ 5, the values were 75.1, 66.7, 97.1, and 13.3 %, respectively. For PSG AHI ≥ 30, the values were 86.9, 36.2, 48.8, and 80 %, respectively. There were no significant modifying effects of age, BMI, gender, hypertension, diabetes, lung disease, and heart disease.

CONCLUSION

The AS has a high sensitivity for detection of OSA with AHI ≥ 15, but only modest specificity. The AS could be a useful component of an OSA screening program; however, negative results should be interpreted cautiously.

Use of electronic data and existing screening tools to identify clinically significant obstructive sleep apnea

OBJECTIVES

To assess the ability of electronic health data and existing screening tools to identify clinically significant obstructive sleep apnea (OSA), as defined by symptomatic or severe OSA.

METHODS

The present retrospective cohort study of 1041 patients referred for sleep diagnostic testing was undertaken at a tertiary sleep centre in Calgary, Alberta. A diagnosis of clinically significant OSA or an alternative sleep diagnosis was assigned to each patient through blinded independent chart review by two sleep physicians. Predictive variables were identified from online questionnaire data, and diagnostic algorithms were developed. The performance of electronically derived algorithms for identifying patients with clinically significant OSA was determined. Diagnostic performance of these algorithms was compared with versions of the STOP-Bang questionnaire and adjusted neck circumference score (ANC) derived from electronic data.

RESULTS

Electronic questionnaire data were highly sensitive (>95%) at identifying clinically significant OSA, but not specific. Sleep diagnostic testing-determined respiratory disturbance index was very specific (specificity ≥95%) for clinically relevant disease, but not sensitive (<35%). Derived algorithms had similar accuracy to the STOP-Bang or ANC, but required fewer questions and calculations.

CONCLUSIONS

These data suggest that a two-step process using a small number of clinical variables (maximizing sensitivity) and objective diagnostic testing (maximizing specificity) is required to identify clinically significant OSA. When used in an online setting, simple algorithms can identify clinically relevant OSA with similar performance to existing decision rules such as the STOP-Bang or ANC.

Upper Airway Stimulation for Obstructive Sleep Apnea: Past, Present, and Future

ABSTRACT

Obstructive sleep apnea (OSA) is an increasingly prevalent clinical problem with significant effects on both personal and public health. Continuous positive airway pressure (CPAP) has demonstrated excellent efficacy and low morbidity; long-term adherence rates approach 50%. Although traditional upper airway surgical procedures target the anatomic component of obstruction, upper airway stimulation tackles the twin goals of improving anatomic and neuromuscular pathology. After decades of trials demonstrating proof of concept of hypoglossal nerve stimulation in animal and human subjects, the results of a large multicenter, prospective trial were recently published. The trial demonstrated that hypoglossal nerve stimulation led to significant improvements in objective and subjective measurements of the severity of OSA. This novel approach is the first to combine sleep surgery techniques with a titratable medical device for the treatment of OSA. Further research is required to define optimal patient selection and device performance and to demonstrate long-term effectiveness.

Automated detection of sleep apnea in infants: A multi-modal approach

This study explores the use and applicability of two minimally invasive sensors, electrocardiogram (ECG) and pulse oximetry, in addressing the high costs and difficulty associated with the early detection of sleep apnea hypopnea syndrome in infants. An existing dataset of 396 scored overnight polysomnography recordings were used to train and test a linear discriminants classifier. The dataset contained data from healthy infants, infants diagnosed with sleep apnea, infants with siblings who had died from sudden infant death syndrome (SIDS) and pre-term infants. Features were extracted from the ECG and pulse-oximetry data and used to train the classifier. The performance of the classifier was evaluated using a leave-one-out cross-validation scheme and an accuracy of 66.7% was achieved, with a specificity of 67.0% and a sensitivity of 58.1%. Although the performance of the system is not yet at the level required for clinical use, this work forms an important step in demonstrating the validity and potential for such low-cost and minimally invasive diagnostic systems.

Correlation of cephalometric and anthropometric measures with obstructive sleep apnea severity

Introduction: Patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) often have associated changes in craniofacial morphology and distribution of body fat, either alone or in combination.

Aim: To correlate cephalometric and anthropometric measures with OSAHS severity by using the apnea-hypopnea index (AHI).

Method: A retrospective cephalometry study of 93 patients with OSAHS was conducted from July 2010 to July 2012. The following measurements were evaluated: body mass index (BMI), neck circumference (NC), waist circumference (WC), hip circumference (HC), the angles formed by the cranial base and the maxilla (SNA) and the mandible (SNB), the difference between SNA and SNB (ANB), the distance from the mandibular plane to the hyoid bone (MP-H), the space between the base of the tongue and the posterior pharyngeal wall (PAS), and the distance between the posterior nasal spine and the tip of the uvula (PNS-P). Means, standard deviations, and Pearson's correlation coefficients were calculated and analyzed.

Results: AHI correlated significantly with BMI (r = 0.207, p = 0.047), NC (r = 0.365, p = 0.000), WC (r = 0.337, p = 0.001), PNS-P (r = 0.282, p = 0.006), and MP-H (r = 0.235, p = 0.023).

Conclusion: Anthropometric measurements (BMI, NC, and WC) and cephalometric measurements (MP-H and PNS-P) can be used as predictors of OSAHS severity.

A Cost-Effectiveness Analysis of Surgery for Middle-Aged Men with Severe Obstructive Sleep Apnea Intolerant of CPAP

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with increased cardiovascular morbidity and mortality. Conventional OSA therapy necessitates indefinite continuous positive airway pressure (CPAP). Although CPAP is an effective treatment modality, up to 50% of OSA patients are intolerant of CPAP. We explore whether surgical modalities developed for those intolerant of CPAP are cost-effective.

METHODS

We construct a lifetime semi-Markov model of OSA that accounts for observed increased risks of stroke, cardiovascular disease, and motor vehicle collisions for a 50-year-old male with untreated severe OSA. Using this model, we compare the cost-effectiveness of (1) no treatment, (2) CPAP only, and (3) CPAP followed by surgery (either palatopharyngeal reconstructive surgery [PPRS] or multilevel surgery [MLS]) for those intolerant to CPAP.

RESULTS

Compared with the CPAP only strategy, CPAP followed by PPRS (CPAP-PPRS) adds 0.265 quality adjusted life years (QALYs) for an increase of $2,767 (discounted 2010 dollars) and is highly cost effective with an incremental cost-effectiveness ratio (ICER) of $10,421/QALY for a 50-year-old male with severe OSA. Compared to a CPAP-PPRS strategy, the CPAP-MLS strategy adds 0.07 QALYs at an increase of $6,213 for an ICER of $84,199/QALY. The CPAP-PPRS strategy appears cost-effective over a wide range of parameter estimates.

CONCLUSIONS

Palatopharyngeal reconstructive surgery appears cost-effective in middle-aged men with severe OSA intolerant of CPAP. Further research is warranted to better define surgical candidacy as well as short-term and long-term surgical outcomes.

COMMENTARY

A commentary on this article appears in this issue on page 509.

Hypertrophic cardiomyopathy associated with sleep apnea: serious implications and cogent management strategy

Obstructive sleep apnea (OSA) affects an estimated 20 million adult Americans and is present in a large proportion of patients with hypertension and in those with other cardiovascular disorders, including hypertrophic cardiomyopathy (HCM). This review seeks to highlight concepts and evidence important to understanding the interactions between OSA and HCM, with particular attention to more recent advances in patient-oriented research. Studies of patients with HCM have found the prevalence of sleep-disordered breathing to range from 40 to 80%. Increased sympathetic activity, impaired vagal activity, increased afterload, insulin resistance and endothelial dysfunction have been proposed as potential mechanisms for the association. Specific questions include whether OSA is important in unmasking symptoms in hitherto undiagnosed patients with HCM, whether OSA in patients with established HCM accelerates disease progression and whether treatment of OSA results in clinical improvement, fewer cardiovascular events and reduced mortality. Because obesity, cardiovascular disease, metabolic syndrome, and diabetes are often present in patients with OSA, it can be difficult to attribute abnormalities evident in the sleep apnea patient with HCM to the effects of OSA, the effects of HCM or synergies between these conditions. Although further research is needed to answer these specific questions, recent investigations have clearly shown the coexistence of OSA and HCM, as well as elucidated the contribution of heightened sympathetic nerve activity in OSA to drug-refractory symptoms and worsening left ventricular outflow tract obstruction. This review aims to highlight the current literature available on the association of OSA and HCM, provide directions for future research and summarize the key features related to this association based on the authors' best understanding and experience.

Impact of Perioperative Fluid Administration on Postoperative Morbidity and Length of Hospital Stay Following Maxillomandibular Advancement for Obstructive Sleep Apnea

PURPOSE

The purpose of this study was to evaluate whether the volume of perioperative fluids administered to patients undergoing maxillomandibular advancement (MMA) for treatment of obstructive sleep apnea (OSA) is associated with an increased incidence of postoperative complications and prolonged length of hospital stay.

MATERIALS AND METHODS

A retrospective cohort study design was implemented and patients undergoing MMA for OSA at the Mayo Clinic were identified from 2001 through 2014. The primary predictor variable was the total volume of intravenous fluids administered during MMA. The primary outcome variable was length of hospital stay in hours. Secondary outcome variables included the presence of complications incurred during postoperative hospitalization. Additional covariates abstracted included basic demographic data, preoperative body mass index, preoperative apnea-hypopnea index, preoperative Charlson comorbidity index, preoperative American Society of Anesthesiologists score, type of intravenous fluid administered, surgical complexity score, duration of anesthesia, duration of surgery, and the use of planned intensive care unit admission. Univariate and multivariable models were developed to assess associations between the primary predictor variable and covariates relative to the primary and secondary outcome variables.

RESULTS

Eighty-eight patients undergoing MMA for OSA were identified. Total fluid volume was significantly associated with increased length of stay (odds ratio [OR] = 1.34, 95% confidence interval [CI], 1.05-1.71; P = .020) in univariate analysis. Total fluid volume did not remain significantly associated with increased length of hospital stay in stepwise multivariable modeling. Total fluid volume was significantly associated with the presence of postoperative complications (OR = 1.69; 95% CI, 1.08-2.63; P = .021) in univariate logistic regression.

CONCLUSION

Fluid administration was not found to be significantly associated with increased length of hospital stay after MMA for OSA. Increased fluid administration might be associated with the presence of postoperative complications after MMA; however, future large multicenter studies will be required to more comprehensively assess this association.

Obstructive sleep apnea among hospitalized patients in Spain, analysis of hospital discharge data 2008-2012

BACKGROUND

The aim of this study is to describe clinical characteristics, diagnostic and therapeutic procedure (polysomnography and continuous positive airway pressure (CPAP)/bi-level positive airway pressure (BPAP)), comorbidity, length of hospital stay (LOHS), discharge destination, and in-hospital mortality (IHM) of patients hospitalized for obstructive sleep apnea (OSA) in Spain over a 5-year study period.

METHODS

We included all patients who were hospitalized for OSA (ICD9-CM code 327.23) as primary or secondary diagnosis between 2008 and 2012. Data were collected from the National Hospital Discharge Database, covering the entire Spanish population.

RESULTS

We identified 196,769 discharges of patients admitted for OSA. The number of patients with OSA as primary or secondary diagnosis increased from 2008 to 2012 from 5358 to 7992 and 14,916 to 51,135 respectively. The mean age was 50.7 ± 20.3 years in patients admitted for OSA as primary diagnosis (n = 32,010) and 63.7 ± 17.6 years in patients admitted for OSA as secondary diagnosis (n = 164,759). The most common secondary diagnoses for patients discharged with a primary diagnosis of OSA was arterial hypertension (19.0%), obesity (16.9%), disorders of lipid metabolism (8.01%) and diabetes mellitus (6.48%). The most common primary diagnoses for patients discharged with a secondary diagnosis of OSA were obesity (12.5%), heart failure (9.6%), and chronic bronchitis (4.5%). The percentage of patients that received continuous positive airway pressure (CPAP)/bi-level positive airway pressure (BPAP) therapy was 11.3%. Patients who received this therapy had a higher length of stay compared with those who did not (10.4 ± 14.1 versus 7.3 ± 9.5 days, respectively, p < 0.05) and were less likely to be discharged to home (87.2 versus 91.1%, p < 0.05). The mortality was higher in the first group of patients (9 versus 5.6%, p < 0.05). Multivariate analysis showed that each year from 2008 to 2012, the mean probability of having OSA as primary diagnosis increased an average of 8%, and 33% as secondary diagnosis, after adjusting for other variables.

CONCLUSIONS

The results of this study reveal a national perspective on the characteristics and management of OSA in hospitalized patients in Spain during the period of 2008-2012. The burden of the disease seems to be increasing in Spain. Clinical studies are needed to provide a better knowledge of OSA in this subgroup of patients.

Impact of excessive daytime sleepiness on the safety and health of farmers in Saskatchewan

BACKGROUND

Sleep disorders may negatively impact the health and well-being of affected individuals. The resulting sleepiness and impaired cognitive functioning may also increase the risks for injury.

OBJECTIVE

To examine the relationship between daytime sleepiness, defined as an Epworth Sleepiness Scale score >10, and self-reported sleep apnea, as potential determinants of farming-related injury and self-perceived physical health.

METHODS

Phase 2 of the Saskatchewan Farm Injury Cohort Study (2013) involved a baseline survey that included 2849 individuals from 1216 farms. A mail-based questionnaire was administered to obtain self-reports regarding sleep, demographics, farm injuries and general physical health. Multilevel logistic regression was used to quantify relationships between excessive daytime sleepiness and health.

RESULTS

The prevalence of excessive daytime sleepiness was 15.1%; the prevalence of diagnosed sleep apnea was 4.0%. Sleepiness was highest in the 60 to 79 (18.7%) and ≥80 (23.6%) years of age groups, and was higher in men (19.0%) than in women (9.3%). Injuries were reported by 8.4% of individuals, and fair or poor health was reported by 6.2%. Adjusting for confounding, individuals with excessive daytime sleepiness appeared more likely to experience a farming-related injury (OR 1.34 [95% CI 0.92 to 1.96]) and were more likely to report poorer physical health (OR 2.19 [95% CI 1.45 to 3.30]) than individuals with normal daytime sleepiness.

CONCLUSION

Excessive daytime sleepiness, a potentially treatable condition, appeared to be common in farmers and to negatively affect their health. Sleep disorder diagnosis and treatment programs did not appear to be used to their full potential in this population.

The effects of continuous positive airways pressure therapy on cardiovascular end points in patients with sleep-disordered breathing and heart failure: a meta-analysis of randomized controlled trials

In patients with sleep-disordered breathing and heart failure, continuous positive airway pressure has been found to be associated with an improvement in cardiovascular end points. We conducted a systematic review of the current literature and a meta-analysis to pool data from 15 published randomized controlled trials. End points analyzed were left ventricular ejection fraction, diastolic blood pressure, systolic blood pressure, heart rate, and mortality. A fixed effects model was used for end points demonstrating homogeneity among included studies, whereas a random effects model was used for end points demonstrating heterogeneity among included studies. A significant improvement in left ventricular ejection fraction was noted with continuous positive airway pressure (mean difference, 5.05%; 95% confidence interval [CI]: 3.72 to 6.38), diastolic blood pressure (mean difference, −1.67; 95% CI: −3.09 to −0.25), and heart rate (mean difference, −5.92; 95% CI: −10.12 to−1.72). No significant changes in mortality (odds ratio, 0.63; 95% CI: 0.40 to 1.00) and systolic blood pressure were noted (mean difference, −6.35; 95% CI: −16.11 to 2.41). The analysis also revealed the need for additional studies to clarify the associations noted and the presence of publication bias with small studies with a paucity of small studies with negative results. In this meta-analysis, treatment with continuous positive airways pressure was associated with improvements in ejection fraction, diastolic blood pressure, and heart rate in patients with sleep-disordered breathing and congestive heart failure.

Obstructive sleep apnea and asthma

Symptoms of sleep-disordered breathing, especially obstructive sleep apnea syndrome (OSAS), are common in asthma patients and have been associated with asthma severity. It is known that asthma symptoms tend to be more severe at night and that asthma-related deaths are most likely to occur during the night or early morning. Nocturnal symptoms occur in 60-74% of asthma patients and are markers of inadequate control of the disease. Various pathophysiological mechanisms are related to the worsening of asthma symptoms, OSAS being one of the most important factors. In patients with asthma, OSAS should be investigated whenever there is inadequate control of symptoms of nocturnal asthma despite the treatment recommended by guidelines having been administered. There is evidence in the literature that the use of continuous positive airway pressure contributes to asthma control in asthma patients with obstructive sleep apnea and uncontrolled asthma.

Obstructive Sleep Apnea and Multiple Anthropometric Indices of General Obesity and Abdominal Obesity among Young Adults

This study aimed to examine the association between obstructive sleep apnea (OSA) and obesity among young adults. A total of 2911 college students in Thailand participated in the study. Anthropometric measurements and blood pressure were taken by trained research staff. Overall, 6.3% of college students had OSA determined by the Berlin Questionnaire, 9.6% were overweight (BMI: 25-29 kg/m²), 4.5% were obese (BMI≥30 kg/m²); 12.4% had abdominal obesity (men: waist circumference≥90 cm; women: waist circumference≥80 cm). There were significant associations between OSA and overweight (odds ratio (OR)=1.72; 95% confidence interval (CI)=1.04-1.85) and obesity (OR=24.23; 95% CI=15.20-38.61), independent of demographic and lifestyle factors, blood pressure, and psychological distress. Students with OSA were more likely to have abdominal obesity than those without OSA (OR=2.09; 95% CI=1.19-3.67). OSA was significantly related to joint effects of general and abdominal obesity. The OSA-obesity associations were robust and evident for both genders, individuals with normal and elevated blood pressure, and those with and without psychological distress. This study shows independent associations of OSA with general and abdominal obesity among young adults. OSA could be a risk factor for obesity and consequent cardiovascular morbidities. OSA screening and treatment might be important for young adults.

The economic impact of obstructive sleep apnea

PURPOSE OF REVIEW

Obstructive sleep apnea (OSA) has a substantial economic impact on healthcare systems. We reviewed parameters affecting healthcare costs (race, low education, and socioeconomic status) on OSA comorbidity, and costs and the effect of OSA treatment on medical costs.

RECENT FINDINGS

OSA is associated with increased cardiovascular disease (CVD) morbidity and substantially increased medical costs. Risk for OSA and resulting CVD are associated with obesity, tobacco smoking, black race, and low socioeconomic status; all these are associated with poor continuous positive airway pressure (CPAP) adherence. Healthcare costs are not normally distributed, that is, the costliest and the sickest upper third of patients consume 65-82% of all medical costs. Only a limited number of studies have explored the effect of CPAP on medical costs.

SUMMARY

Costs of untreated OSA may double the medical expenses mainly because of CVD. Identifying the costliest, sickest upper third of OSA patients will reduce expenses to healthcare systems. Studies exploring the effect of CPAP on medical costs are essential. In addition, tailoring intervention programs to reduce barriers to adherence have the potential to improve CPAP treatment, specially in at-risk populations that are sicker and consume more healthcare costs.

Spousal involvement and CPAP adherence: a dyadic perspective

Poor adherence to continuous positive airway pressure (CPAP) treatment is associated with substantial health care costs, morbidity and mortality, and has been a leading obstacle in the effective management of obstructive sleep apnea (OSA). Successful interventions to improve CPAP adherence may ultimately include a variety of components. For patients living with spouses (refers to all domestic partners), the spouse will likely be an integral component to any successful intervention. Developing understanding of the role of spouses in adherence to CPAP has been identified to be a critical research need. This review expands the investigation of CPAP adherence to a broader context, from an exclusive focus on individual patients to a dyadic perspective encompassing both patients and their spouses. A conceptual framework based on social support and social control theories is proposed to understand spousal involvement in CPAP adherence. Methodologies for future investigations are discussed, along with implications for developing interventions that engage both patients and their spouses to improve CPAP use.

Obstructive sleep apnea is associated with higher healthcare utilization in elderly patients

BACKGROUND

Obstructive sleep apnea (OSA) is an important cause of morbidity in the elderly population. Limited data are available regarding the healthcare utilization and predisposing conditions related to OSA in the elderly. Our aim was to evaluate the healthcare utilization and the conditions associated with new and chronic diagnosis of OSA in a large cohort of elderly patients in the Veterans Health Administration (VHA).

MATERIALS AND METHODS

This retrospective cohort study used inpatient and outpatient VHA data to identify the individuals diagnosed with OSA using ICD-9 codes during the fiscal years 2003-2005. Primary outcomes were emergency department (ED) visits and hospitalizations. Multivariable logistic regression analysis was performed to identify the demographic and clinical characteristics associated with new and chronic diagnosis of OSA.

RESULTS

Of 1,867,876 elderly veterans having 2 years of care, 82,178 (4.4%) were diagnosed with OSA. Individuals with OSA were younger and more likely to have chronic diseases than those without OSA. Individuals with chronic OSA were more likely to have diagnoses of congestive heart failure (CHF), pulmonary circulation disorders, COPD, and obesity and less likely to have diagnoses of hypertension, osteoarthritis, and stroke than individuals with newly diagnosed OSA. The proportion of patients with new OSA diagnosis who required at least one ED visit was higher than the proportion of chronic OSA and no OSA patients (37%, 32%, and 15%, respectively; P-value <0.05). The proportion of new OSA patients who required at least one hospitalization was also higher than the proportion of chronic OSA and no OSA patients (24%, 17%, and 7%, respectively; P-value <0.05).

CONCLUSION

Patients with OSA had a higher incidence of healthcare utilization compared to patients without OSA. New OSA patients had a higher rate of healthcare utilization in the year of diagnosis compared to chronic patients and patients without OSA. Early OSA recognition may reduce healthcare utilization in these patients.

Effect of recording duration on the diagnostic accuracy of out-of-center sleep testing for obstructive sleep apnea

STUDY OBJECTIVES

This study investigated the minimum recording time needed during out-of-center sleep testing (OCST) to accurately diagnose the presence and severity of obstructive sleep apnea (OSA).

DESIGN AND SETTING

A retrospective analysis was conducted of OCSTs performed from October 2009 to May 2012 at the Mayo Clinic Center of Sleep Medicine using the portable Embletta™ system.

PATIENTS OR PARTICIPANTS

Demographic information was collected for patients who underwent OCSTs during the study period, including presenting symptoms, examination findings, and comorbidities.

INTERVENTION

Each study was divided into 60-, 120-, 180-, 240-, 300-, 360-, and 420-min intervals beginning at the recording start time to determine the respiratory event index (REI) for each of these time intervals. These interval values were then compared to the original REI derived from the total recording time (REITRT) by a paired t-test and concordance correlation coefficient (CCC).

MEASUREMENTS AND RESULTS

There were significant differences between the REITRT and the REI from the 60-min (P < 0.0001), 120-min (0.0001), 180-min (0.003) and 240-min (0.006) intervals with a lack of concordance, suggesting these intervals are poor diagnostic correlates for the REITRT. REIs determined at 300, 360, and 420 min were not significantly different from the REITRT and had highly significant CCCs, 0.963, 0.987, and 0.995, respectively.

CONCLUSIONS

The results suggest that at least 300 min recording time during out-of-center sleep testing is needed for accurate diagnosis of obstructive sleep apnea and determination of obstructive sleep apnea severity.

Sleep apnea and occupational accidents: Are oral appliances the solution?

BACKGROUND

Dental practitioners have a key role in the quality of life and prevention of occupational accidents of workers with Obstructive Sleep Apnea Syndrome (OSAS).

AIM

The aim of this study was to review the impact of OSAS, the Continuous Positive Airway Pressure (CPAP) therapy, and the evidence regarding the use of oral appliances (OA) on the health and safety of workers.

MATERIALS AND METHODS

Searches were conducted in MEDLINE (PubMed), Lilacs and Sci ELO. Articles published from January 1980 to June 2014 were included.

RESULTS

The research retrieved 2188 articles and 99 met the inclusion criteria. An increase in occupational accidents due to reduced vigilance and attention in snorers and patients with OSAS was observed. Such involvements were related to excessive daytime sleepiness and neurocognitive function impairments. The use of OA are less effective when compared with CPAP, but the results related to excessive sleepiness and cognitive performance showed improvements similar to CPAP. Treatments with OA showed greater patient compliance than the CPAP therapy.

CONCLUSION

OSAS is a prevalent disorder among workers, leads to increased risk of occupational accidents, and has a significant impact on the economy. The CPAP therapy reduces the risk of occupational accidents. The OA can improve the work performance; but there is no scientific evidence associating its use with occupational accidents reduction. Future research should focus on determining the cost-effectiveness of OA as well as its influence and efficacy in preventing occupational accidents.

Diagnosis of obstructive sleep apnea using pulse oximeter derived photoplethysmographic signals

OBJECTIVES

Increasing awareness of the high prevalence of obstructive sleep apnea (OSA) and its impact on health in conjunction with high cost, inconvenience, and short supply of in-lab polysomnography (PSG) has led to the development of more convenient, affordable, and accessible diagnostic devices. We evaluated the reliability and accuracy of a single-channel (finger pulse-oximetry) photoplethysmography (PPG)-based device for detection of OSA (Morpheus Ox).

METHODS

Among a cohort of 73 patients referred for in-laboratory evaluation of OSA, 65 were simultaneously monitored with the PPG based device while undergoing PSG. Among these, 19 had significant cardiopulmonary comorbidities. Using the PSG as the "gold standard," the sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), as well as the positive likelihood ratio (+LR) for an apnea hypopnea index (AHI)PSG > 5/h and AHIPSG > 15/h were calculated for the PPG.

RESULTS

Valid results were available for 65 subjects. Mean age: 52.1 ± 14.2, Male: 52%, and BMI: 36.3 ± 9.7 kg/m(2). Positive correlation was found between PPG-derived and PSG-derived AHI (r = 0.81, p < 0.001). For AHIPSG > 5/h, sensitivity was 80%, specificity 86%, PPV 93%, NPV 68%, and +LR was 5.9. For AHIPSG > 15/h, sensitivity was 70%, specificity 91%, PPV 80%, NPV 85%, and +LR was 7.83. The corresponding areas under the receiver operator curves were 0.91 and 0.9.

CONCLUSIONS

PPG-derived data compare well with simultaneous in-lab PSG in the diagnosis of suspected OSA among patients with and without cardiopulmonary comorbidities.

CITATION

Romem A; Romem A; Koldobskiy D; Scharf SM. Diagnosis of obstructive sleep apnea using pulse oximeter derived photoplethysmographic signals.

What is known about the experiences of using CPAP for OSA from the users' perspective? A systematic integrative literature review

Economic, social and personal costs of untreated obstructive sleep apnoea (OSA) are high. Continuous positive airway pressure (CPAP) is recommended and cost effective. Increasing OSA prevalence may accompany predicted globally increasing obesity.

OBJECTIVE

To synthesise international evidence regarding personal experiences using CPAP for OSA.

METHODS

A systematic integrative literature review was conducted and quality assessment criteria applied.

RESULTS

22, of 538, identified papers met inclusion criteria. Thematic analysis identified three themes: 1) users' beliefs about CPAP influence users' experiences of CPAP; 2) CPAP users are primed to reflect negatively on experiences of CPAP; and 3) spouse and family influence users' experiences of CPAP. Personality and attitude impact expectations about CPAP prior to use, whilst engagement of spouse and family also influence experiences. Analysis highlighted that users' reporting of CPAP experiences is constrained by investigator defined assessment methods. Overall, research relating to experiences using CPAP is limited.

CONCLUSION

Users' perspectives of CPAP are constrained by researchers' concern with non-compliance. Typically experiences are not defined by the user, but from an 'expert' healthcare perspective, using words which frame CPAP as problematic. Family and social support is a significant, but neglected area of experiencing CPAP warranting further investigation. More information from users is required to determine how CPAP can be managed successfully.

Diagnostic accuracy of level 3 portable sleep tests versus level 1 polysomnography for sleep-disordered breathing: a systematic review and meta-analysis

BACKGROUND

Greater awareness of sleep-disordered breathing and rising obesity rates have fueled demand for sleep studies. Sleep testing using level 3 portable devices may expedite diagnosis and reduce the costs associated with level 1 in-laboratory polysomnography. We sought to assess the diagnostic accuracy of level 3 testing compared with level 1 testing and to identify the appropriate patient population for each test.

METHODS

We conducted a systematic review and meta-analysis of comparative studies of level 3 versus level 1 sleep tests in adults with suspected sleep-disordered breathing. We searched 3 research databases and grey literature sources for studies that reported on diagnostic accuracy parameters or disease management after diagnosis. Two reviewers screened the search results, selected potentially relevant studies and extracted data. We used a bivariate mixed-effects binary regression model to estimate summary diagnostic accuracy parameters.

RESULTS

We included 59 studies involving a total of 5026 evaluable patients (mostly patients suspected of having obstructive sleep apnea). Of these, 19 studies were included in the meta-analysis. The estimated area under the receiver operating characteristics curve was high, ranging between 0.85 and 0.99 across different levels of disease severity. Summary sensitivity ranged between 0.79 and 0.97, and summary specificity ranged between 0.60 and 0.93 across different apnea-hypopnea cut-offs. We saw no significant difference in the clinical management parameters between patients who underwent either test to receive their diagnosis.

INTERPRETATION

Level 3 portable devices showed good diagnostic performance compared with level 1 sleep tests in adult patients with a high pretest probability of moderate to severe obstructive sleep apnea and no unstable comorbidities. For patients suspected of having other types of sleep-disordered breathing or sleep disorders not related to breathing, level 1 testing remains the reference standard.

Medicare long-term CPAP coverage policy: a cost-utility analysis

STUDY OBJECTIVES

CPAP is an effective treatment for OSA that may reduce health care utilization and costs. Medicare currently reimburses the costs of long-term CPAP therapy only if the patient is adherent during a 90-day trial. If not, Medicare requires a repeat polysomnogram (PSG) and another trial which seems empirically not cost-effective. We modeled the cost-effectiveness of current Medicare policy compared to an alternative policy (clinic-only) without the adherence criterion and repeat PSG.

DESIGN

Cost-utility and cost-effectiveness analysis.

SETTING

U.S. Medicare Population.

PATIENTS OR PARTICIPANTS

N/A.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

We created a decision tree modeling (1) clinic only follow-up vs. (2) current Medicare policy. Costs were assigned based on Medicare reimbursement rates in 2012. Sensitivity analyses were conducted to test our assumptions. We estimated cumulative costs, overall adherence, and QALY gained for a 5-year time horizon from the perspective of Medicare as the payer. Current Medicare policy is more costly than the clinic-only policy but has higher net adherence and improved utility. Current Medicare policy compared to clinic-only policy costs $30,544 more per QALY.

CONCLUSIONS

Current CMS policy promotes early identification of those more likely to adhere to CPAP therapy by requiring strict adherence standards. The policy effect is to deny coverage to those unlikely to use CPAP long-term and prevent wasted resources. Future studies are needed to measure long-term adherence in an elderly population with and without current adherence requirements to verify the cost-effectiveness of a policy change.

Prevalence of signs and symptoms of laryngopharyngeal reflux in snorers with suspected obstructive sleep apnea

Obstructive sleep apnea (OSA) is believed to be correlated with laryngopharyngeal reflux (LPR).

Objective

To study the prevalence of signs and symptoms of reflux in snorers with suspected OSA.

Method

This cross-sectional study enrolled 74 patients assessed positive for OSA with the Berlin questionnaire. The subjects were followed up at the sleep disorder ward of a university center. Studied variables included the BMI, the Epworth sleepiness scale, the reflux symptom index (RSI), the reflux finding score (RFS), and their subdomains related to increased inflammation. The correlations between sleep questionnaires, reflux scales, and their subdomains were deemed statistically significant when p < 0.05.

Results

Ninety-eight percent of the subjects had symptoms and signs suggestive of LPR; prevalence was significantly higher among obese individuals (p = 0.002).

Conclusion

The significant difference seen in the prevalence of signs of inflammation suggestive of LPR when obese and non-obese subjects with suspected OSA were compared indicates that obesity may affect inflammatory findings of the pharynx and larynx. The high prevalence of symptoms and signs of reflux in patients with suspected OSA calls for more studies on the matter.

Co-occurring insomnia and obstructive sleep apnea

STUDY OBJECTIVES

Prior research investigating co-occurring insomnia/obstructive sleep apnea (CIO) has mainly focused on comparing comorbid patients, obstructive sleep apnea (OSA), and insomnia (INS) to those with OSA alone. This approach is informative but omits the potentially interesting comparison of comorbid patients to those with INS alone. Our study used an incomplete factorial design, crossing OSA (present or absent) with INS (present or absent) to more clearly focus on the question, is comorbid INS an epiphenomenon of OSA or an independent disorder?

METHODS

Our study was an archival analysis from the database of a sleep center comparing consecutively diagnosed patients characterized as OSA or INS. A third group, CIO, was derived from the OSA group. Our study was conducted at an American Academy of Sleep Medicine-accredited sleep disorders center. We studied 299 patients, including 94 OSA, 97 INS, and 108 CIO. Patients ranged from ages 15 to 86years.

RESULTS

Groups were compared on polysomnography (PSG), sleep pattern, sleep stages, sleep pathology, self-reported sleep concerns, and self-reported daytime functioning. From a consecutive group of OSA patients, we estimate the prevalence of CIO at 67.4%. Based mainly on multivariate analysis of covariance (MANCOVA) controlling for demographic differences between groups, we found few if any significant differences between CIO and INS alone or between CIO and OSA alone.

CONCLUSIONS

The clinical presentation of CIO is indistinguishable from INS alone, both with respect to PSG findings and to self-reported sleep onset and sleep maintenance disturbance. We observed a weak relation between OSA severity and co-occurring INS. These data are consistent with the view that INS with co-occurring OSA is an independent, self-sustaining disorder. We hypothesized that in some unknown proportion of cases, OSA initially instigated the INS, but the INS was then perpetuated and reshaped by sleep concerns and self-defeating compensatory behaviors.

Screening for obstructive sleep apnoea in obesity and diabetes--potential for future approaches

BACKGROUND

It is recognised that sleep-disordered breathing (SDB), in particular, obstructive sleep apnoea (OSA) is associated with obesity and diabetes. The complications of OSA include dysregulation of metabolic and cardiovascular homeostasis. With the growing population of diabetes and obesity globally, it is becoming apparent that identifying and screening patients who are at risk is becoming increasingly crucial. Many patients may remain unaware of the potential diagnosis and continue to be undiagnosed. The high prevalence of OSA poses a demanding challenge to healthcare providers in order to provide sufficient resources and facilities for patient diagnosis and treatment.

DESIGN

In this article, we review the evidence in favour of screening populations deemed to be at increased risk of OSA, with particular reference to patients with obesity and diabetes. We consider the recent advances in potential screening methods that may allow new prognostic and predictive tools to be developed. A detailed search of Medline and Web of Science electronic databases for relevant articles in English was performed.

RESULTS

Apart from the use of screening tools such as questionnaires and clinical decision models, there is increasing evidence to suggest that there are differences in biological parameters in patients with OSA. Although further studies are required, there may be potential for such biomarkers to contribute to and augment the screening process. However, the significance of such biological tools remains to be elucidated.

CONCLUSIONS

A fundamental role for improved screening in patients with conditions such as obesity and diabetes can enable early interventions that may improve health outcomes relating to the adverse consequences of OSA. The future will see further research being carried out in the development of potential screening methods with emphasis on the selection of patients at risk of sleep disorders, thereby allowing more detailed physiological studies to be carried out where needed.

Long-term effect of weight loss on obstructive sleep apnea severity in obese patients with type 2 diabetes

STUDY OBJECTIVES

To examine whether the initial benefit of weight loss on obstructive sleep apnea (OSA) severity at 1 year is maintained at 4 years.

DESIGN

Randomized controlled trial with follow-up at 1, 2, and 4 years.

SETTING

4 Look AHEAD clinical centers.

PARTICIPANTS

Two hundred sixty-four obese adults with type 2 diabetes and OSA.

INTERVENTIONS

Intensive lifestyle intervention with a behavioral weight loss program or diabetes support and education.

MEASUREMENTS

Change in apnea-hypopnea index on polysomnogram.

RESULTS

The intensive lifestyle intervention group's mean weight loss was 10.7 ± 0.7 (standard error), 7.4 ± 0.7, and 5.2 ± 0.7 kg at 1, 2, and 4 years respectively, compared to a less than 1-kg weight loss for the control group at each time (P < 0.001). Apnea-hypopnea index difference between groups was 9.7 ± 2.0, 8.0 ± 2.0, and 7.7 ± 2.3 events/h at 1, 2 and 4 years respectively (P < 0.001). Change in apnea-hypopnea index over time was related to the amount of weight loss (P < 0.0001) and intervention, independent of weight loss (P = 0.001). Remission of OSA at 4 years was 5 times more common with intensive lifestyle intervention (20.7%) than diabetes support and education (3.6%).

CONCLUSIONS

Among obese adults with type 2 diabetes and OSA, intensive lifestyle intervention produced greater reductions in weight and apnea-hypopnea index over a 4 year period than did diabetes support and education. Beneficial effects of intensive lifestyle intervention on apneahypopnea index at 1 year persisted at 4 years, despite an almost 50% weight regain. Effect of intensive lifestyle intervention on apnea-hypopnea index was largely, but not entirely, due to weight loss.

Obstructive sleep apnea and cardiovascular disease in blacks: a call to action from the Association of Black Cardiologists

Obstructive sleep apnea (OSA) has emerged as a new and important risk factor for cardiovascular disease (CVD). Over the last decade, epidemiologic and clinical research has consistently supported the association of OSA with increased cardiovascular (CV) morbidity and mortality. Such evidence prompted the American Heart Association to issue a scientific statement describing the need to recognize OSA as an important target for therapy in reducing CV risk. Emerging facts suggest that marked racial differences exist in the association of OSA with CVD. Although both conditions are more prevalent in blacks, almost all National Institutes of Health-funded research projects evaluating the relationship between OSA and CV risk have been conducted in predominantly white populations. There is an urgent need for research studies investigating the CV impact of OSA among high-risk minorities, especially blacks. This article first examines the evidence supporting the association between OSA and CVD and reviews the influence of ethnic/racial differences on this association. Public health implications of OSA and future directions, especially regarding minority populations, are discussed.

Death by a thousand cuts in Alzheimer's disease: hypoxia--the prodrome

A wide range of clinical consequences may be associated with obstructive sleep apnea (OSA) including systemic hypertension, cardiovascular disease, pulmonary hypertension, congestive heart failure, cerebrovascular disease, glucose intolerance, impotence, gastroesophageal reflux, and obesity, to name a few. Despite this, 82 % of men and 93 % of women with OSA remain undiagnosed. OSA affects many body systems, and induces major alterations in metabolic, autonomic, and cerebral functions. Typically, OSA is characterized by recurrent chronic intermittent hypoxia (CIH), hypercapnia, hypoventilation, sleep fragmentation, peripheral and central inflammation, cerebral hypoperfusion, and cerebral glucose hypometabolism. Upregulation of oxidative stress in OSA plays an important pathogenic role in the milieu of hypoxia-induced cerebral and cardiovascular dysfunctions. Strong evidence underscores that cerebral amyloidogenesis and tau phosphorylation--two cardinal features of Alzheimer's disease (AD), are triggered by hypoxia. Mice subjected to hypoxic conditions unambiguously demonstrated upregulation in cerebral amyloid plaque formation and tau phosphorylation, as well as memory deficit. Hypoxia triggers neuronal degeneration and axonal dysfunction in both cortex and brainstem. Consequently, neurocognitive impairment in apneic/hypoxic patients is attributable to a complex interplay between CIH and stimulation of several pathological trajectories. The framework presented here helps delineate the emergence and progression of cognitive decline, and may yield insight into AD neuropathogenesis. The global impact of CIH should provide a strong rationale for treating OSA and snoring clinically, in order to ameliorate neurocognitive impairment in aged/AD patients.

Employer-mandated sleep apnea screening and diagnosis in commercial drivers

INTRODUCTION

Obstructive sleep apnea (OSA) is common among commercial drivers and associated with health/safety risks, leading several trucking firms to mandate OSA screening.

METHODS

A total of 19,371 commercial drivers were screened for OSA with an online questionnaire (Somni-Sage reg) through employer mandates. Questionnaire and polysomnography results were analyzed retrospectively.

RESULTS

Screening categorized 5908 drivers (30%) as higher risk. To date, employers have sent 2103 higher-risk drivers for polysomnography, demonstrating that 68% of high-risk drivers tested had an apnea-hypopnea index (AHI) greater than 10 and 80% had an AHI of 5 or more. A conservative prevalence estimate for OSA (AHI > 10) was 21% among the drivers studied.

CONCLUSIONS

Online screening followed by polysomnography for high-risk drivers demonstrates as many as 21% of commercial drivers may have OSA. Mandatory screening can have a high yield among commercial drivers.

The utility of routine EEG in the diagnosis of sleep disordered breathing

Sleep disordered breathing (SDB) is a common medical condition. Its manifestations of snoring, nocturnal choking, arousals, and sleep fragmentation can lead to excessive daytime sleepiness, neuropsychological slowing, lapses of consciousness, and accidents that can be misinterpreted as epileptic phenomena. Moreover, patients with documented epilepsy commonly exhibit similar symptomatology because of the undiagnosed coexistence of sleep apnea. Therefore, a large proportion of patients referred to the electroencephalogram (EEG) laboratory primarily to confirm or refute the diagnosis of epilepsy could suffer from latent sleep apnea and the routine EEG has the potential to divulge it. We retrospectively evaluated the reporting of sleep apnea symptomatology (snoring, choking, gasping/deep breath, apnea, desaturation, excessive drowsiness) in routine inpatient and outpatient adult EEG studies performed in our institution over the past 12 years (39,130 studies, approximately half of which recorded at least early stages of sleep). Comparisons were performed with the medical records to ascertain the coexistence of objectively diagnosed SDB with polysomnography before or after the EEG study and the importance of reporting variations in assisting with the diagnosis. Two illustrative examples are provided. Sixty-nine EEG studies were identified, performed primarily to confirm, or refute the diagnosis of epilepsy. The mean age of the subjects at EEG was 64 years (range 30-89), and 55 (80%) were male. 36% of them suffered from known epilepsy. Snoring was the most commonly reported sign in 48 (70%) of the studies, followed by arousals in 29 (42%), apnea in 16 (23%), excessive drowsiness in 13 (19%), gasping/deep breath in 9 (13%), and desaturation in 7 (10%). A sleep disorder was suggested in 25 (36%) of the interpretations and a direct recommendation for a sleep study was made in 22 of them (32%). This interpretation was included in the impression of the report in 21 (30%) of the cases, in the detail in 20 (30%) of the cases and in both in 28 (40%). Only 14 (20%) patients underwent polysomnography, and all of them were formally diagnosed with SDB. Seven (50%) of them were diagnosed with obstructive sleep apnea, 2 (14%) with central sleep apnea, 3 (22%) with both, 1 (7%) with upper airways resistance syndrome, and 1 (7%) with primary snoring. From these 14 patients, 9 (64%) were diagnosed with a sleep study performed after the EEG, 4 (29%) before the EEG interpretation, and 1 (7%) had a repeat study after the EEG. In the logistic regression model applied, with the exception of the presence of arousals (odds ratio = 4.63, P = 0.033), none of the aforementioned symptomatology or the reporting of suspicion for SDB or the location (impression vs. detail) of the reporting showed a statistically significant association with the completion of a sleep study. Routine EEG offers a unique opportunity of direct clinical observation along with electrophysiologic and cardiorespiratory monitoring. When sleep is recorded, it can help identify clinical and electrographic features of sleep apnea and prompt confirmation with a polysomnogram in the appropriate clinical context. It can therefore serve as a valuable, adjunctive tool for the diagnosis of SDB. Our data highlight that potential but unveil its decreased use in the neurology community. Increased awareness is required by the EEG technologists, interpreting neurologists, and referring physicians, regarding reporting and using sleep apnea features on the EEG.

Probabilistic neural network approach for the detection of SAHS from overnight pulse oximetry

Diagnosis of sleep apnea hypopnoea syndrome (SAHS) depends on the apnea-hypopnea index determined by the standard in-laboratory overnight polysomnography (PSG). PSG is a costly, labor intensive and, at times, inaccessible approach. Because of the high demand, the need for timely diagnosis and the associated costs, novel methods for SAHS detection are required. In this study, a novel multivariate system is proposed for SAHS detection from the analysis of overnight blood oxygen saturation (SpO2). 115 subjects with SAHS suspicion were studied. A starting set of 17 time domain, stochastic, frequency-domain and nonlinear features were initially computed from SpO2 recordings. Sequential forward feature selection and a probabilistic neural network with leave-one-out cross-validation were applied. Oxygen desaturations below a 4 % threshold within 30 s (ODI430), restorations of 4 % within 10 s (RES4), median value (Sat50), SD1 Poincaré descriptor and the relative power in the 0.013-0.067 Hz frequency band (PSD15/75) formed the optimum features subset. 92.4 % sensitivity and 95.9 % specificity were achieved. Results significantly outperformed the univariate and multivariate approaches reported in literature. The outcome is a simple cost-effective tool that could be used as an alternative or supplementary method in a domiciliary approach to early diagnosis of SAHS.

Obstructive sleep apnea and dyslipidemia: evidence and underlying mechanism

INTRODUCTION

Over the past half century, evidence has been accumulating on the emergence of obstructive sleep apnea (OSA), the most prevalent sleep-disordered breathing, as a major risk factor for cardiovascular disease. A significant body of research has been focused on elucidating the complex interplay between OSA and cardiovascular risk factors, including dyslipidemia, obesity, hypertension, and diabetes mellitus that portend increased morbidity and mortality in susceptible individuals.

CONCLUSION

Although a clear causal relationship of OSA and dyslipidemia is yet to be demonstrated, there is increasing evidence that chronic intermittent hypoxia, a major component of OSA, is independently associated and possibly the root cause of the dyslipidemia via the generation of stearoyl-coenzyme A desaturase-1 and reactive oxygen species, peroxidation of lipids, and sympathetic system dysfunction. The aim of this review is to highlight the relationship between OSA and dyslipidemia in the development of atherosclerosis and present the pathophysiologic mechanisms linking its association to clinical disease. Issues relating to epidemiology, confounding factors, significant gaps in research and future directions are also discussed.

Importance and management of chronic sleep apnoea in cardiology

Sleep apnoea is a common, yet underestimated, chronic disorder with a major impact on morbidity and mortality in the general population. It is quickly becoming recognized as an independent risk factor for cardiovascular impairment. Hypertension, coronary artery disease, diabetes, cardiovascular rhythm and conduction abnormalities, cerebrovascular disease, and heart failure have all been linked to this syndrome. This review will explore the critical connection between sleep apnoea and chronic cardiovascular diseases while highlighting established and emerging diagnostic and treatment strategies.

Nonparametric inference for median costs with censored data

Increasingly, estimations of health care costs are used to evaluate competing treatments or to assess the expected expenditures associated with certain diseases. In health policy and economics, the primary focus of these estimations has been on the mean cost, because the total cost can be derived directly from the mean cost, and because information about total resources utilized is highly relevant for policymakers. Yet, the median cost also could be important, both as an intuitive measure of central tendency in cost distribution and as a subject of interest to payers and consumers. In many prospective studies, cost data collection is sometimes incomplete for some subjects due to right censoring, which typically is caused by loss to follow-up or by limited study duration. Censoring poses a unique challenge for cost data analysis because of so-called induced informative censoring, in that traditional methods suited for survival data generally are invalid in censored cost estimation. In this article, we propose methods for estimating the median cost and its confidence interval (CI) when data are subject to right censoring. We also consider the estimation of the ratio and difference of two median costs and their CIs. These methods can be extended to the estimation of other quantiles and other informatively censored data. We conduct simulation and real data analysis in order to examine the performance of the proposed methods.

Sleep disorders and demand for medical services: evidence from a population-based longitudinal study

Background

The aim of this study was to investigate whether insomnia and obstructive sleep apnea (OSA) were predictors of hospitalizations or emergency department visits during two years following the Sao Paulo Epidemiologic Sleep Study (EPISONO) sample.

Methods and Findings

All participants (n = 1,101) who underwent a baseline evaluation between July and December 2007 were contacted in December 2009 and asked to fill out a questionnaire about body weight changes, number of hospitalizations and visits to the emergency department. Participants lost during the follow-up period represented 3.2% (n = 35) and 7 subjects had died. Hospitalizations were reported by 116 volunteers (10.5%) and emergency department visits were reported by 136 participants (12.4%). The average body mass index (BMI) did not vary significantly between the first and the second assessment [26.7(95%CI:26.3–27.1) vs. 26.9(26.5–27.4) kg/m2]. After adjusting for confounders, a multiple logistic regression model revealed that female gender [1.4(1.0–1.9)], age ≥40 years, insomnia diagnosed according to the DSM-IV criteria [1.6(1.0–2.6)], and apnea-hypopnea index ≥15 [1.5(1.0–2.2)] were predictors of hospitalizations and/or demand for emergency services.

Conclusion

Our study of a probabilistic sample of the Sao Paulo inhabitants shows that over a period of two years, insomnia and OSA were both associated with health impairment. Considering the high prevalence and public health burden of sleep disorders, the consequences of untreated disease for both the individual and society are undeniable and should be addressed.