Association of Periodic Limb Movements and Obstructive Sleep Apnea With Risk of Cardiovascular Disease and Mortality.

BACKGROUND: Obstructive sleep apnea is a well-established risk factor for cardiovascular disease (CVD). Recent studies have also linked periodic limb movements during sleep to CVD. We aimed to determine whether periodic limb movements during sleep and obstructive sleep apnea are independent or synergistic factors for CVD events or death. METHODS AND RESULTS: We examined data from 1049 US veterans with an apnea-hypopnea index (AHI) <30 events/hour. The primary outcome was incident CVD or death. Cox proportional hazards regression assessed the relationships between the AHI, periodic limb movement index (PLMI), and the AHI×PLMI interaction with the primary outcome. We then examined whether AHI and PLMI were associated with primary outcome after adjustment for age, sex, race and ethnicity, obesity, baseline risk of mortality, and Charlson Comorbidity Index. During a median follow-up of 5.1 years, 237 of 1049 participants developed incident CVD or died. Unadjusted analyses showed an increased risk of the primary outcome with every 10-event/hour increase in PLMI (hazard ratio [HR], 1.08 [95% CI, 1.05-1.13]) and AHI (HR, 1.17 [95% CI, 1.01- 1.37]). Assessment associations of AHI and PLMI and their interaction with the primary outcome revealed no significant interaction between PLMI and AHI. In fully adjusted analyses, PLMI, but not AHI, was associated with an increased risk of primary outcome: HR of 1.05 (95% CI, 1.00-1.09) per every 10 events/hour. Results were similar after adjusting with Framingham risk score. CONCLUSIONS: Our study revealed periodic limb movements during sleep as a risk factor for incident CVD or death among those who had AHI <30 events/hour, without synergistic association between periodic limb movements during sleep and obstructive sleep apnea.

Suboptimal Sleep Duration Is Associated With Poorer Neuroimaging Brain Health Profiles in Middle-Aged Individuals Without Stroke or Dementia.

BACKGROUND: The American Heart Association's Life's Simple 7, a public health construct capturing key determinants of cardiovascular health, became the Life's Essential 8 after the addition of sleep duration. The authors tested the hypothesis that suboptimal sleep duration is associated with poorer neuroimaging brain health profiles in asymptomatic middle-aged adults. METHODS AND RESULTS: The authors conducted a prospective magnetic resonance neuroimaging study in middle-aged individuals without stroke or dementia enrolled in the UK Biobank. Self-reported sleep duration was categorized as short (<7 hours), optimal (7-<9 hours), or long (≥9 hours). Evaluated neuroimaging markers included the presence of white matter hyperintensities (WMHs), volume of WMH, and fractional anisotropy, with the latter evaluated as the average of 48 white matter tracts. Multivariable logistic and linear regression models were used to test for an association between sleep duration and these neuroimaging markers. The authors evaluated 39 771 middle-aged individuals. Of these, 28 912 (72.7%) had optimal, 8468 (21.3%) had short, and 2391 (6%) had long sleep duration. Compared with optimal sleep, short sleep was associated with higher risk of WMH presence (odds ratio, 1.11 [95% CI, 1.05-1.18]; P<0.001), larger WMH volume (beta=0.06 [95% CI, 0.04-0.08]; P<0.001), and worse fractional anisotropy profiles (beta=-0.04 [95% CI, -0.06 to -0.02]; P=0.001). Compared with optimal sleep, long sleep duration was associated with larger WMH volume (beta=0.04 [95% CI, 0.01-0.08]; P=0.02) and worse fractional anisotropy profiles (beta=-0.06 [95% CI, -0.1 to -0.02]; P=0.002), but not with WMH presence (P=0.6). CONCLUSIONS: Among middle-aged adults without stroke or dementia, suboptimal sleep duration is associated with poorer neuroimaging brain health profiles. Because these neuroimaging markers precede stroke and dementia by several years, these findings are consistent with other findings evaluating early interventions to improve this modifiable risk factor.

Insomnia and Early Incident Atrial Fibrillation: A 16-Year Cohort Study of Younger Men and Women Veterans.

Background There is growing consideration of sleep disturbances and disorders in early cardiovascular risk, including atrial fibrillation (AF). Obstructive sleep apnea confers risk for AF but is highly comorbid with insomnia, another common sleep disorder. We sought to first determine the association of insomnia and early incident AF risk, and second, to determine if AF onset is earlier among those with insomnia. Methods and Results This retrospective analysis used electronic health records from a cohort study of US veterans who were discharged from military service since October 1, 2001 (ie, post-9/11) and received Veterans Health Administration care, 2001 to 2017. Time-varying, multivariate Cox proportional hazard models were used to examine the independent contribution of insomnia diagnosis to AF incidence while serially adjusting for demographics, lifestyle factors, clinical comorbidities including obstructive sleep apnea and psychiatric disorders, and health care utilization. Overall, 1 063 723 post-9/11 veterans (Mean age=28.2 years, 14% women) were followed for 10 years on average. There were 4168 cases of AF (0.42/1000 person-years). Insomnia was associated with a 32% greater adjusted risk of AF (95% CI, 1.21-1.43), and veterans with insomnia showed AF onset up to 2 years earlier. Insomnia-AF associations were similar after accounting for health care utilization (adjusted hazard ratio [aHR], 1.27 [95% CI, 1.17-1.39]), excluding veterans with obstructive sleep apnea (aHR, 1.38 [95% CI, 1.24-1.53]), and among those with a sleep study (aHR, 1.26 [95% CI, 1.07-1.50]). Conclusions In younger adults, insomnia was independently associated with incident AF. Additional studies should determine if this association differs by sex and if behavioral or pharmacological treatment for insomnia attenuates AF risk.

Empagliflozin in patients with type 2 diabetes mellitus and chronic obstructive pulmonary disease.

AIMS: Type 2 diabetes mellitus (T2DM) and chronic obstructive pulmonary disease (COPD) often co-exist, yielding increased risk of cardiovascular (CV) complications including heart failure (HF). We assessed risk of cardiorenal outcomes, mortality and safety in patients with versus without COPD in the EMPA-REG OUTCOME trial. METHODS: Patients (n = 7,020) with T2DM and CV disease (CVD) were treated with empagliflozin (10 mg or 25 mg) or placebo. Cox regression was used to assess COPD subgroup (placebo only) associations with, and treatment effects of empagliflozin versus placebo on first hospitalization for HF (HHF), CV death, all-cause mortality, incident/worsening nephropathy, and all-cause hospitalization. RESULTS: At baseline, patients with COPD (n = 707) had more HF and used insulin more frequently than those without COPD. During follow-up in the placebo group, those with baseline COPD had increased risk of HHF (HR 2.15 [95% CI 1.32, 3.49]), HHF/CV death (1.60 [1.10, 2.33]), incident/worsening nephropathy (1.68 [1.26, 2.24]), all-cause hospitalization (1.44 [1.19, 1.74]) and all-cause death (1.60 [1.09, 2.35]) compared to those without COPD. Empagliflozin consistently reduced all clinical outcomes, irrespective of COPD status (interaction p-values 0.14 to 0.96), with a confirmed safety profile. CONCLUSIONS: In patients with T2DM and CVD, COPD increased the risk of mortality and cardiorenal outcomes, including HF. Empagliflozin consistently reduced these outcomes versus placebo regardless of COPD, suggesting that empagliflozin's benefits in patients with T2DM and CVD are not mitigated by the presence of COPD.

A SAS macro for modelling periodic data using cosinor analysis.

BACKGROUND AND OBJECTIVE: Cosinor analysis, developed by Franz Hallberg and colleagues in the 1960s, allows for the fitting of a cosine curve to data of a known period. Cosinor analysis is frequently used in the analysis of biological rhythm data. While software exists to perform these analyses, we are not aware of any published SAS procedures or macros which would facilitate them. METHODS: To meet this gap, we herein describe SAS macros which perform cosinor analyses that assume either normally or gamma distributed outcomes and fixed period. The macros can 1) produce datasets with cosinor parameters including acrophase, mesor, amplitude, nadir and test for rhythmicity 2) output datasets with fitted and observed values from the model, and 3) plot the resulting curve and underlying data. RESULTS: We demonstrate the use of these macros with data from our research on circadian rhythms of heart rate and sleep in critically ill patients. CONCLUSIONS: Cosinor analysis provides a parsimonious and intuitive set of estimates to summarize periodic data. We are hopeful that the publication of our macro will allow a wider spectrum of users to avail themselves of this technique.

Polysomnographic Phenotypes of Obstructive Sleep Apnea and Incident Type 2 Diabetes: Results from the DREAM Study.

Rationale: Obstructive sleep apnea (OSA) is associated with cardiovascular disease and incident type 2 diabetes (T2DM). Seven OSA phenotypes, labeled on the basis of their most distinguishing polysomnographic features, have been shown to be differentially associated with incident cardiovascular disease. However, little is known about the relevance of polysomnographic phenotypes for the risk of T2DM. Objectives: To assess whether polysomnographic phenotypes are associated with incident T2DM and to compare the predictive value of baseline polysomnographic phenotypes with the Apnea-Hypopnea Index (AHI) for T2DM. Methods: The study included 840 individuals without baseline diabetes from a multisite observational U.S. veteran cohort who underwent OSA evaluation between 2000 and 2004, with follow-up through 2012. The primary outcome was incident T2DM, defined as no diagnosis at baseline and a new physician diagnosis confirmed by fasting blood glucose >126 mg/dL during follow-up. Relationships between the seven polysomnographic phenotypes (1. mild, 2. periodic limb movements of sleep [PLMS], 3. non-rapid eye movement and poor sleep, 4. rapid eye movement and hypoxia, 5. hypopnea and hypoxia, 6. arousal and poor sleep, and 7. combined severe) and incident T2DM were investigated using Cox proportional hazards regression and competing risk regression models with and without adjustment for baseline covariates. Likelihood ratio tests were conducted to compare the predictive value of the phenotypes with the AHI. Results: During a median follow-up period of 61 months, 122 (14.5%) patients developed incident T2DM. After adjustment for baseline sociodemographics, fasting blood glucose, body mass index, comorbidities, and behavioral risk factors, hazard ratios among persons with "hypopnea and hypoxia" and "PLMS" phenotypes as compared with persons with "mild" phenotype were 3.18 (95% confidence interval [CI], 1.53-6.61] and 2.26 (95% CI, 1.06-4.83) for incident T2DM, respectively. Mild OSA (5 ⩽ AHI < 15) (vs. no OSA) was directly associated with incident T2DM in both unadjusted and multivariable-adjusted regression models. The addition of polysomnographic phenotypes, but not AHI, to known T2DM risk factors greatly improved the predictive value of the computed prediction model. Conclusions: Polysomnographic phenotypes "hypopnea and hypoxia" and "PLMS" independently predict risk of T2DM among a predominantly male veteran population. Polysomnographic phenotypes improved T2DM risk prediction comared with the use of AHI.

Obstructive Sleep Apnea as a Risk Factor for Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE: To determine whether obstructive sleep apnea (OSA) is associated with intracerebral hemorrhage (ICH) risk, we assessed premorbid OSA exposure of patients with nontraumatic ICH and matched controls. METHODS: Ethnic/Racial Variations of Intracerebral Hemorrhage is a multicenter, case-control study evaluating risk factors for ICH that recruited 3000 cases with ICH and 3000 controls. OSA status was ascertained using the Berlin Questionnaire as a surrogate for premorbid OSA. We performed logistic regression analyses to evaluate the association between OSA and ICH. RESULTS: Two thousand and sixty-four (71%) cases and 1516 (52%) controls were classified as having OSA by the Berlin Questionnaire. Cases with OSA were significantly more likely to be male and have hypertension, heart disease, hyperlipidemia, and higher body mass index compared with those without OSA. OSA was more common among cases compared with controls (71% versus 52%, odds ratio, 2.28 [95% CI, 2.05-2.55]). In a multivariable logistic regression model, OSA was associated with increased risk for ICH (odds ratio, 1.47 [95% CI, 1.29-1.67]). CONCLUSIONS: OSA is a risk factor for ICH.

Day-to-day Relationships between Physical Activity and Sleep Characteristics among People with Heart Failure and Insomnia.

OBJECTIVE: Examine the bidirectional relationships between within-person day-to-day fluctuations in physical activity (PA) and sleep characteristics among people with heart failure (HF) and insomnia. PARTICIPANTS: Ninety-seven community-dwelling adults [median age 61.9 (interquartile range 55.3,70.9) years, female 41%] with stable HF and insomnia (insomnia severity index >7). METHODS: This sub-study longitudinally analyzed 15 consecutive days and nights of wrist actigraphy recordings, that were collected for baseline data prior to participation in a randomized controlled trial of cognitive behavioral therapy for insomnia. We used two-level mixed models of within- (daily) and between-participants variation to predict daytime PA counts/minutes from sleep variables (total sleep time, sleep efficiency) and predict sleep variables from PA. RESULTS: PA counts/minutes were low compared to prior cohorts that did not have HF (209 (166,259)) and negatively associated with NYHA class (standardized coefficient ßs = -0.14, p < .01), age (ßs = -0.13, p = .01), comorbidities (ßs = -0.19, p < .01), and body mass index (ßs = -0.12, p = .04). After adjustment for all significant covariates, the within-participant association of total sleep time with next-day PA was estimated to be positive among participants with NYHA class II-IV HF (ßs = 0.09, p = .01), while the within-participant association of PA with same-night total sleep time was estimated to be positive among participants aged ≥60 years (ßs = 0.10, p = .03). CONCLUSIONS: Depending upon age and HF class, daytime PA was associated with longer same-night sleep and/or longer sleep was associated with greater next-day PA. Among those with more advanced HF, realistic sleep improvements were associated with clinically meaningful PA gains the next day.

Perceived Stress, Subjective, and Objective Symptoms of Disturbed Sleep in Men and Women with Stable Heart Failure.

Objective/Background: Sleep disturbance is prevalent among patients with heart failure (HF) and is associated with increased morbidity and mortality. Stress also affects health and quality of life among patients with cardiovascular disease and likely plays a prominent role in HF. However, little is known about the associations between stress and sleep among HF patients.Participants: One hundred fifty-three stable New York Heart Association (NYHA) Classification I-IV HF patients with at least low symptoms of insomnia (Mage:63.0 ± 12.8, 42% Women).Methods: We examined baseline stress, sleep disturbance, and sleep-related characteristics from a randomized controlled trial of cognitive behavioral therapy for insomnia, including the Perceived Stress Scale, Insomnia Severity Index, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Sleep Disturbance Questionnaire, Dysfunctional Beliefs about Sleep Scale, PROMIS Cognitive Ability, SF-36 Mental Health, and wrist actigraphy. We used Pearson correlations and general linear models to assess stress-sleep associations, including the potential moderating effects of sex and symptom severity (NYHA).Results: There were moderate-to-large correlations between stress and self-reported sleep disturbance, dysfunctional beliefs about sleep, cognitive ability, and mental health (p's < 0.01). High stress was associated with more objectively-measured (i.e., actigraph-assessed) awakenings and sleep fragmentation among women than men (ß = - 0.04, p < 0.01; ß = - 0.71, p = 0.04). Relationships between stress and objectively-measured sleep did not vary by symptom severity.Conclusions: Perceived stress is related to sleep disturbance among HF patients, and effects may be sex-dependent. Subsequent research should determine the temporal links between sleep and stress, and optimal opportunities for intervention among HF patients.

The Impact of Empagliflozin on Obstructive Sleep Apnea and Cardiovascular and Renal Outcomes: An Exploratory Analysis of the EMPA-REG OUTCOME Trial.

OBJECTIVE: To explore the effects of empagliflozin on the incidence of obstructive sleep apnea (OSA) and its effects on metabolic, cardiovascular (CV), and renal outcomes among participants with or without OSA in the EMPA-REG OUTCOME trial. RESEARCH DESIGN AND METHODS: Participants with diabetes and CV disease were randomized to empagliflozin (10 and 25 mg) or placebo daily in addition to standard of care. OSA was assessed by investigator report using Medical Dictionary for Regulatory Activities version 18.0, and CV outcomes were independently adjudicated. Analyses were performed using multivariable-adjusted Cox regression models. RESULTS: OSA was reported in 391 of 7,020 (5.6%) participants at baseline. Those with OSA were more likely to be male (83% vs. 71%) and to have moderate to severe obesity (BMI ≥35 kg/m2; 55% vs. 18%). Over a median of 3.1 years, empagliflozin had similar placebo-adjusted reductions in HbA1c, waist circumference, and systolic blood pressure, regardless of OSA status, but a larger effect on weight (adjusted mean ± SE difference at week 52: OSA vs. no OSA -2.9 ± 0.5 vs. -1.9 ± 0.1 kg). Incidence of 3-point major adverse CV events, CV death, heart failure hospitalization, and incident or worsening nephropathy in the placebo group was 1.2- to 2.0-fold higher for those with baseline OSA compared with those without. Empagliflozin significantly reduced the risk for outcomes regardless of OSA status (P-interaction all >0.05). Fifty patients reported a new diagnosis of OSA through 7 days after medication discontinuation, and this occurred less often with empagliflozin treatment (hazard ratio 0.48 [95% CI 0.27, 0.83]). CONCLUSIONS: In EMPA-REG OUTCOME, participants with OSA had greater comorbidity and higher frequency of CV and renal events. Empagliflozin had favorable effects on risk factors and CV and renal outcomes regardless of preexisting OSA and may also reduce the risk for new-onset OSA.

Pilot Observational Study to Detect Diurnal Variation and Misalignment in Heart Rate Among Critically Ill Patients.

Circadian disruption is common in critically ill patients admitted to the intensive care unit (ICU). Understanding and treating circadian disruption in critical illness has significant potential to improve critical illness outcomes through improved cognitive, immune, cardiovascular, and metabolic function. Measurement of circadian alignment (i.e., circadian phase) can be resource-intensive as it requires frequent blood or urine sampling over 24 or more hours. Less cumbersome methods of assessing circadian alignment would advance investigations in this field. Thus, the objective of this study is to examine the feasibility of using continuous telemetry to assess diurnal variation in heart rate (HR) among medical ICU patients as a proxy for circadian alignment. In exploratory analyses, we tested for associations between misalignment of diurnal variation in HR and death during hospital admission. This was a prospective observational cohort study embedded within a prospective medical ICU biorepository. HR data were continuously collected (every 5 s) via telemetry systems for the duration of the medical ICU admission; the first 24 h of this data was analyzed. Patients were extensively characterized via medical record chart abstraction and patient interviews. Of the 56 patients with complete HR data, 48 (86%) had a detectable diurnal variation. Of these patients with diurnal variation, 39 (81%) were characterized as having the nadir of their HR outside of the normal range of 02:00-06:00 ("misalignment"). Interestingly, no deaths occurred in the patients with normally aligned diurnal variation; in contrast, there were seven deaths (out of 39 patients) in patients who had misaligned diurnal variation in HR. In an exploratory analysis, we found that the odds ratio of death for misaligned vs. aligned patients was increased at 4.38; however, this difference was not statistically significant (95% confidence interval 0.20-97.63). We conclude that diurnal variation in HR can be detected via continuous telemetric monitoring of critically ill patients. A majority of these patients with diurnal variation exhibited misalignment in their first 24 h of medical ICU admission. Exploratory analyses suggest possible associations between misalignment and death.

Obstructive Sleep Apnea and Pain Intensity in Young Adults.

Rationale: Prior research studies on the association of obstructive sleep apnea (OSA) and pain intensity have examined older patients; there is a need to understand the relationship between OSA and pain intensity among younger adults.Objectives: To examine whether young adults with diagnosed OSA are more likely to report higher pain intensity compared with those without OSA.Methods: We conducted a cross-sectional analysis of a cohort study of Operation Enduring Freedom, Operation Iraqi Freedom, and Operation New Dawn veterans who had at least one visit to a Veterans Health Administration primary care clinic between 2001 and 2014. OSA was identified using one inpatient or two outpatient International Classification of Diseases, Ninth Revision codes from electronic medical records. Average pain intensity (based on the self-reported 0-10 numeric rating scale over a 12-month period) was categorized as no pain/mild (0-3; no pain) and moderate/severe (4-10; significant pain). Covariates included age, sex, education, race, mental health diagnoses, headache diagnoses, pain diagnoses, hypertension, diabetes, body mass index, and smoking status. Multivariate logistic regression models were used, and multiple imputation was performed to generate values for missing variables.Results: We identified 858,226 young adults (mean age 30 yr [SD = 7]), of whom 91,244 (10.6%) had a diagnosis of OSA and 238,587 (27.8%) reported moderate/severe pain for the 12-month average. with young adults without OSA, those with OSA were more likely to report moderate/severe pain intensity (adjusted odds ratio, 1.09; 95% confidence interval, 1.08-1.11) even after controlling for covariates.Conclusions: We found that young adults with OSA have greater odds of comorbid moderate/severe pain. Because of the high prevalence of chronic pain in younger adults, this study highlights the need to understand the impact of OSA diagnosis and treatment on pain intensity. Future work is needed to determine the role of effective OSA treatment on pain intensity over time in these young adults.

Associations between obstructive sleep apnea and prescribed opioids among veterans.

ABSTRACT: Sleep disruption caused by obstructive sleep apnea (OSA) may be associated with hyperalgesia and may contribute to poor pain control and use of prescription opioids. However, the relationship between OSA and opioid prescription is not well described. We examine this association using cross-sectional data from a national cohort of veterans from recent wars enrolled from October 1, 2001 to October 7, 2014. The primary outcome was the relative risk ratio (RRR) of receiving opioid prescriptions for acute (<90 days/year) and chronic (≥90 days/year) durations compared with no opioid prescriptions. The primary exposure was a diagnosis of OSA. We used multinomial logistic regression to control for factors that may affect diagnosis of OSA or receipt of opioid prescriptions. Of the 1,149,874 patients (mean age 38.0 ± 9.6 years) assessed, 88.1% had no opioid prescriptions, 9.4% had acute prescriptions, and 2.5% had chronic prescriptions. Ten percent had a diagnosis of OSA. Patients with OSA were more likely to be older, male, nonwhite, obese, current or former smokers, have higher pain intensity, and have medical and psychiatric comorbidities. Controlling for these differences, patients with OSA were more likely to receive acute (RRR 2.02 [95% confidence interval 1.98-2.06]) or chronic (RRR 2.15 [2.09-2.22]) opioids. Further dividing opioid categories by high vs low dosage did not yield substantially different results. Obstructive sleep apnea is associated with a two-fold likelihood of being prescribed opioids for pain. Clinicians should consider incorporating OSA treatment into multimodal pain management strategies; OSA as a target for pain management should be further studied.

Phenotypic Subtypes of OSA: A Challenge and Opportunity for Precision Medicine.

Current strategies for the management of OSA reflect a one-size-fits-all approach. Diagnosis and severity of OSA are based on the apnea-hypopnea index and treatment initiated with CPAP, followed by trials of alternatives (eg, oral appliances) if CPAP "fails." This approach does not consider the heterogeneity of individuals with OSA, reflected by varying risk factors, pathophysiological causes, clinical manifestations, and consequences. Recently, studies using analytic approaches such as cluster analysis have taken advantage of this heterogeneity to identify OSA phenotypes, or subtypes of patients with unique characteristics, that may enable more personalized approaches to prognostication and treatment. Examples include symptom-based subtypes such as "excessively sleepy" and "disturbed sleep" with differing impact of CPAP on symptoms and health-related quality of life. Polysomnographic subtypes, distinguished by respiratory event association with hypoxemia, arousals, or both, exhibit varying risks of cardiovascular disease and response to therapy. This review summarizes the findings from recent cluster analysis studies in sleep apnea and synthesizes common themes to describe the potential role (and limitations) of phenotypic subtypes in precision medicine for OSA. It also highlights future directions, including linking of phenotypes to clinically relevant outcomes, rigorous and transparent assessment of phenotype reproducibility, and need for tools that categorize patients into subtypes, to prospectively validate phenotype-based prognostication and treatment approaches. Finally, we highlight the critical need to include women and more racially/ethnically diverse populations in this area of research if we are to leverage the heterogeneity of OSA to improve patient lives.

Mechanisms of reduced sleepiness symptoms in heart failure and obstructive sleep apnea.

Patients with both heart failure and obstructive sleep apnea often have poor, repeatedly disrupted sleep, and yet they frequently do not complain of excessive daytime sleepiness. Understanding this lack of perceived sleepiness is crucial for the case identification and treatment of obstructive sleep apnea in the heart failure population at high risk of this disease, especially given the association between untreated obstructive sleep apnea and mortality among patients with heart failure. In this review, we present epidemiologic evidence concerning the lack of sleepiness symptoms in heart failure and obstructive sleep apnea, explore possible mechanistic explanations for this relationship, assess the benefits of treatment in this population, discuss implications for clinical practice and explore directions for future research.

Varying Hypopnea Definitions Affect Obstructive Sleep Apnea Severity Classification and Association With Cardiovascular Disease.

STUDY OBJECTIVES: To compare clinical features and cardiovascular risks in patients with obstructive sleep apnea (OSA) based on ≥ 3% desaturation or arousal, and ≥ 4% desaturation hypopnea criteria. METHODS: This is a cross-sectional analysis of 1,400 veterans who underwent polysomnography for suspected sleep-disordered breathing. Hypopneas were scored using ≥ 4% desaturation criteria per the American Academy of Sleep Medicine (AASM) 2007 guidelines, then re-scored using ≥ 3% desaturation or arousal criteria per AASM 2012 guidelines. The effect on OSA disease categorization by these two different definitions were compared and correlated with symptoms and cardiovascular associations using unadjusted and adjusted logistic regression. RESULTS: The application of the ≥ 3% desaturation or arousal definition of hypopnea captured an additional 175 OSA diagnoses (12.5%). This newly diagnosed OSA group (OSAnew) was symptomatic with daytime sleepiness similarly to those in whom OSA had been diagnosed based on ≥ 4% desaturation criteria (OSA4%). The OSAnew group was more obese and more likely to be male than those without OSA based on either criterion (No-OSA). However, the OSAnew group was younger, less obese, more likely female, and had a lesser smoking history compared to the OSA4% group. Those with any severity of OSA4% had an increased adjusted odds ratio for arrhythmias (odds ratio = 1.95 [95% confidence interval 1.37-2.78], P = .0155). The more inclusive hypopnea definition (ie, ≥ 3% desaturation or arousal) resulted in recategorization of OSA diagnosis and severity, and attenuated the increased odds ratio for arrhythmias observed in mild and moderate OSA4%. However, severe OSA based on ≥ 3% desaturation or arousals (OSA3%/Ar) remained a significant risk factor for arrhythmias. OSA based on any definition was not associated with ischemic heart disease or heart failure. CONCLUSIONS: The most current AASM criteria for hypopnea identify a unique group of patients who are sleepy, but who are not at increased risk for cardiovascular disease. Though the different hypopnea definitions result in recategorization of OSA severity, severe disease whether defined by ≥ 3% desaturation/arousals or ≥ 4% desaturation remains predictive of cardiac arrhythmias. COMMENTARY: A commentary on this article appears in this issue on page 1971.

Creating Naptime: An Overnight, Nonpharmacologic Intensive Care Unit Sleep Promotion Protocol.

INTRODUCTION: Patients in the intensive care unit (ICU) have significantly disrupted sleep. Sleep disruption is believed to contribute to ICU delirium, and ICU delirium is associated with increased mortality. Experts recommend sleep promotion as a means of preventing or shortening the duration of delirium. ICU Sleep promotion protocols are highly complex and difficult to implement. Our objective is to describe the development, pilot implementation, and revision of a medical ICU sleep promotion protocol. METHODS: Naptime is a clustered-care intervention that provides a rest period between 00:00 and 04:00. We used literature review, medical chart review, and stakeholder interviews to identify sources of overnight patient disturbance. With stakeholder input, we developed an initial protocol that we piloted on a small scale. Then, using protocol monitoring and stakeholder feedback, we revised Naptime and adapted it for unitwide implementation. RESULTS: We identified sound, patient care, and patient anxiety as important sources of overnight disturbance. The pilot protocol altered the timing of routine care with a focus on medications and laboratory draws. During the pilot, there were frequent protocol violations for laboratory draws and for urgent care. Stakeholder feedback supported revision of the protocol with a focus on providing 60- to 120-minute rest periods interrupted by brief clusters of care between 00:00 and 04:00. DISCUSSION: Four-hour blocks of rest may not be possible for all medical ICU patients, but interruptions can be minimized to a significant degree. Involvement of all stakeholders and frequent protocol reevaluation are needed for successful adoption of an overnight rest period.

Association between death and loss of stage N2 sleep features among critically Ill patients with delirium.

PURPOSE: Critically ill patients experience significant sleep disruption. In this study of ICU patients with delirium, we evaluated associations between the loss of stage N2 features (K-complexes, sleep spindles), grade of encephalopathy based on electroencephalography (EEG), and intensive care unit (ICU) outcomes. We hypothesized that loss of stage N2 features is associated with more severe grades of encephalopathy and worse ICU outcomes including death. MATERIALS AND METHODS: This was an observational cohort study of 93 medical ICU patients without primary acute brain injury who underwent continuous EEG. Type and severity of critical illness, sedative-hypnotic use, length of stay, modified Rankin Scale at hospital discharge, and death during hospitalization were abstracted from the medical record. EEG was evaluated for grade of encephalopathy and sleep features. RESULTS: Patients without K-complexes or without sleep spindles had more severe encephalopathy and higher odds of death. The odds ratio for patients without K-complexes was 18.8 (p = .046). The odds ratio for patients without sleep spindles was 6.3 (p = .036). CONCLUSIONS: Loss of stage N2 features is common and associated with more severe encephalopathy and higher odds of death. The absence of either Stage N2 feature, K complexes or sleep spindles, may have important prognostic value.