A Systematic Review of Operative Team Familiarity on Metrics of Efficiency, Patient Outcomes, Cost, and Team Satisfaction.

OBJECTIVE: This study seeks to systematically review the current literature on how surgical team familiarity relates to metrics of operative efficiency. BACKGROUND: The operating room (OR) is a complex environment involving numerous multidisciplinary interactions that must interface precisely to achieve a successful outcome. METHODS: A systematic search of the PubMed database was prospectively registered in the National Institute for Health Research PROSPERO database (CRD 42020181046) and performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Exposure variable was team familiarity and outcome measures included operative efficiency, patient outcomes, costs, and/or team satisfaction. RESULTS: Of 1123 articles screened, 15 studies involving 24,340 operations met inclusion criteria. All studies were limited to an individual specialty, procedure, or both. The effects of more familiar teams were most pronounced in decreasing operative times [standardized mean difference of -0.51 (95% confidence interval: -1.00, -0.02), P =0.04], whereas the reported impacts on patient clinical outcomes, material waste, and team satisfaction were much more heterogenous. CONCLUSIONS: Improving OR team familiarity is associated with superior operative efficiency and may be associated with other favorable measures. Further inferences are limited by literature heterogeneity, yet could be a novel focus for improving OR performance.

Identifying Medicare Beneficiaries Accessing Transgender-Related Care in the Era of ICD-10.

Purpose: The study purpose was to describe trends in the size and demographics of the population of transgender Medicare beneficiaries identified using International Classification of Diseases (ICD) Clinical Modification codes over time. We also assessed how the change from ICD, Ninth Revision (ICD-9) diagnosis codes to ICD, 10th Revision (ICD-10) diagnosis codes in October 2015 has affected the ability to identify transgender beneficiaries within claims data. Methods: We used Medicare Fee-for-Service claims within the Centers for Medicare & Medicaid Services Chronic Conditions Data Warehouse from 2010 through 2016 to identify transgender beneficiaries. We linked these data to Medicare enrollment records to study demographic trends. Results: Within the Medicare program, the number of beneficiaries identified as transgender through claims data in each year has increased from 2088 beneficiaries in 2010 to 10,242 beneficiaries in 2016 (a 390% increase). The highest numbers of transgender beneficiaries were identified in 2015 and 2016, which coincide with the change to ICD-10. Similarly, more beneficiaries were identified as transgender in the 12 months after the change to ICD-10 (N = 8733) than in the 12 months before (N = 4857). Conclusion: Given that a first and critical step to better understand and eliminate health disparities and deliver culturally competent care is to identify and characterize the population of interest, this study provides an innovative view into how the change to the ICD-10 coding system affects the ability to study a transgender cohort within Medicare claims data.

Health Care Utilization and Cost Outcomes of a Comprehensive Dementia Care Program for Medicare Beneficiaries.

Importance: An estimated 4 to 5 million Americans have Alzheimer disease or another dementia. Objective: To determine the health care utilization and cost outcomes of a comprehensive dementia care program for Medicare fee-for-service beneficiaries. Design, Setting, and Participants: In this case-control study, we used a quasiexperimental design to compare health care utilization and costs for 1083 Medicare fee-for-service beneficiaries enrolled in the University of California Los Angeles Health System Alzheimer and Dementia Care program between July 1, 2012, and December 31, 2015, with those of 2166 similar patients with dementia not participating in the program. Patients in the comparison cohort were selected using the zip code of residence as a sampling frame and matched with propensity scores, which included demographic characteristics, comorbidities, and prior-year health care utilization. We used Medicare claims data to compare utilization and cost outcomes for the 2 groups. Interventions: Patients in the dementia care program were comanaged by nurse practitioners and physicians, and the program consisted of structured needs assessments of patients and their caregivers, creation and implementation of individualized dementia care plans with input from primary care physicians, monitoring and revising care plans, referral to community organizations for dementia-related services and support, and access to a clinician for assistance and advice 24 hours per day, 7 days per week. Main Outcomes and Measures: Admissions to long-term care facilities; average difference-in-differences per quarter over the 3-year intervention period for all-cause hospitalization, emergency department visits, 30-day hospital readmissions, and total Medicare Parts A and B costs of care. Program costs were included in the cost estimates. Results: Program participants (n = 382 men, n = 701 women; mean [SD] age, 82.10 [7.90] years; age range 54-101 years) were less likely to be admitted to a long-term care facility (hazard ratio, 0.60; 95% CI, 0.59-0.61) than those not participating in the dementia care program (n = 759 men, n = 1407 women; mean [SD] age, 82.42 [8.50] years; age range, 34-103 years). There were no differences between groups in terms of hospitalizations, emergency department visits, or 30-day readmissions. The total cost of care to Medicare, excluding program costs, was $601 less per patient per quarter (95% CI, -$1198 to -$5). After accounting for the estimated program costs of $317 per patient per quarter, the program was cost neutral for Medicare, with an estimated net cost of -$284 (95% CI, -$881 to $312) per program participant per quarter. Conclusions and Relevance: Comprehensive dementia care may reduce the number of admissions to long-term care facilities, and depending on program costs, may be cost neutral or cost saving. Wider implementation of such programs may help people with dementia stay in their communities.

Transgender Medicare Beneficiaries and Chronic Conditions: Exploring Fee-for-Service Claims Data.

PURPOSE: Data on the health and well-being of the transgender population are limited. However, using claims data we can identify transgender Medicare beneficiaries (TMBs) with high confidence. We seek to describe the TMB population and provide comparisons of chronic disease burden between TMBs and cisgender Medicare beneficiaries (CMBs), thus laying a foundation for national level TMB health disparity research. METHODS: Using a previously validated claims algorithm based on ICD-9-CM codes relating to transsexualism and gender identity disorder, we identified a cohort of TMBs using Medicare Fee-for-Service (FFS) claims data. We then describe the demographic characteristics and chronic disease burden of TMBs (N = 7454) and CMBs (N = 39,136,229). RESULTS: Compared to CMBs, a greater observed proportion of TMBs are young (under age 65) and Black, although these differences vary by entitlement. Regardless of entitlement, TMBs have more chronic conditions than CMBs, and more TMBs have been diagnosed with asthma, autism spectrum disorder, chronic obstructive pulmonary disease, depression, hepatitis, HIV, schizophrenia, and substance use disorders. TMBs also have higher observed rates of potentially disabling mental health and neurological/chronic pain conditions, as well as obesity and other liver conditions (nonhepatitis), compared to CMBs. CONCLUSION: This is the first systematic look at chronic disease burden in the transgender population using Medicare FFS claims data. We found that TMBs experience multiple chronic conditions at higher rates than CMBs, regardless of Medicare entitlement. TMBs under age 65 show an already heavy chronic disease burden which will only be exacerbated with age.

Health Indicators for Older Sexual Minorities: National Health Interview Survey, 2013-2014.

PURPOSE: Advances in lesbian, gay, and bisexual (sexual minority [SM]) acceptance and equality have been made in the past decade. However, certain SM subgroups continue to be disadvantaged due to lack of data and, thus, lack of knowledge about these populations. Data for older sexual minorities are especially lacking and will be increasingly important as more sexual minorities enter older age. This research explores results from a nationally representative health survey to elucidate some health indicators for older sexual minorities. METHODS: Data from the 2013 and 2014 National Health Interview Surveys (NHIS) were pooled for increased sample size, and established research methods were followed as recommended by prior NHIS sexual orientation studies. We conducted descriptive analyses on the differences between SM and heterosexual groups, aged 65 years and older, for 12 health indicators. RESULTS: Four out of the 12 health indicators were significantly different for sexual minorities, and three out of those four indicated positive health outcomes or behaviors when compared with heterosexuals. Sexual minorities were more than three times as likely to receive HIV testing as heterosexual peers. Sexual minorities were more likely to receive an influenza vaccination, and much more likely to report excellent or very good health, than their heterosexual peers. Sexual minorities were more than twice as likely to report binge drinking, which is consistent with prior research for adult sexual minorities. CONCLUSION: This analysis is the first to examine national data on health indicators for sexual minorities, aged 65 years and older, using NHIS data. As more surveys begin to collect SMdata and more years of data are collected by NHIS, a clearer picture of the health of older adult sexual minorities should emerge.

Associations between sleep-disordered breathing, nocturnal hypoxemia, and subsequent cognitive decline in older community-dwelling men: the Osteoporotic Fractures in Men Sleep Study.

OBJECTIVES: To determine whether sleep-disordered breathing (SDB), a group of disorders common in older adults characterized by breathing pauses during sleep often accompanied by hypoxemia, is associated with cognitive decline. DESIGN: Population-based longitudinal study. SETTING: Six centers in the United States. PARTICIPANTS: Community-dwelling older men (N=2,636; aged 76.0±5.3) without probable mild cognitive impairment or dementia followed for 3.4±0.5 years. MEASUREMENTS: SDB was measured using in-home polysomnography: nocturnal hypoxemia (≥1% of sleep time with oxygen saturation (SaO2)<90%, oxygen desaturation index (ODI: number of oxygen desaturations of ≥3% per hour of sleep)) and apnea-hypopnea index (AHI, number of apneas and hypopneas at ≥3% desaturation per hour of sleep). Cognitive decline was measured using the Modified Mini-Mental State Examination (3MS) and the Trail-Making Test Part B (Trails B) at baseline and two follow-up points. Associations between predictors and cognitive decline were examined using linear mixed models adjusted for multiple confounders. Models were further adjusted for potential mediators (sleep duration, sleep fragmentation, resting SaO2). RESULTS: Nocturnal hypoxemia was related to greater decline on the 3MS. Men with 1% or more of sleep time with SaO2 less than 90% had an adjusted annualized decline of 0.43 points, compared with 0.25 for men in the reference group (P=.003). For each 5-point increase in ODI, there was an average annualized decline of 0.36 points (P=.01). Results were robust to further adjustment for potential mediators. The association between AHI and cognitive decline did not reach significance. No associations were seen with SDB and decline on the Trails B. CONCLUSION: In older community-dwelling men, there was a modest association between nocturnal hypoxemia and global cognitive decline, suggesting the importance of overnight oxygenation for cognitive function.

Sleep disordered breathing, fatigue, and sleepiness in HIV-infected and -uninfected men.

STUDY OBJECTIVES: We investigated the association of HIV infection and highly active antiretroviral therapy (HAART) with sleep disordered breathing (SDB), fatigue, and sleepiness. METHODS: HIV-uninfected men (HIV-; n = 60), HIV-infected men using HAART (HIV+/HAART+; n = 58), and HIV-infected men not using HAART (HIV+/HAART-; n = 41) recruited from two sites of the Multicenter AIDS cohort study (MACS) underwent a nocturnal sleep study, anthropometric assessment, and questionnaires for fatigue and the Epworth Sleepiness Scale. The prevalence of SDB in HIV- men was compared to that in men matched from the Sleep Heart Health Study (SHHS). RESULTS: The prevalence of SDB was unexpectedly high in all groups: 86.7% for HIV-, 70.7% for HIV+/HAART+, and 73.2% for HIV+/HAART-, despite lower body-mass indices (BMI) in HIV+ groups. The higher prevalence in the HIV- men was significant in univariate analyses but not after adjustment for BMI and other variables. SDB was significantly more common in HIV- men in this study than those in SHHS, and was common in participants with BMIs <25 kg/m2. HIV+ men reported fatigue more frequently than HIV- men (25.5% vs. 6.7%; p = 0.003), but self-reported sleepiness did not differ among the three groups. Sleepiness, but not fatigue, was significantly associated with SDB. CONCLUSIONS: SDB was highly prevalent in HIV- and HIV+ men, despite a normal or slightly elevated BMI. The high rate of SDB in men who have sex with men deserves further investigation. Sleepiness, but not fatigue, was related to the presence of SDB. Clinicians caring for HIV-infected patients should distinguish between fatigue and sleepiness when considering those at risk for SDB, especially in non-obese men.

Associations of objectively and subjectively measured sleep quality with subsequent cognitive decline in older community-dwelling men: the MrOS sleep study.

STUDY OBJECTIVES: To examine associations of objectively and subjectively measured sleep with subsequent cognitive decline. DESIGN: A population-based longitudinal study. SETTING: Six centers in the United States. PARTICIPANTS: Participants were 2,822 cognitively intact community-dwelling older men (mean age 76.0 ± 5.3 y) followed over 3.4 ± 0.5 y. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: OBJECTIVELY MEASURED SLEEP PREDICTORS FROM WRIST ACTIGRAPHY: total sleep time (TST), sleep efficiency (SE), wake after sleep onset (WASO), number of long wake episodes (LWEP). Self-reported sleep predictors: sleep quality (Pittsburgh Sleep Quality Index [PSQI]), daytime sleepiness (Epworth Sleepiness Scale [ESS]), TST. Clinically significant cognitive decline: five-point decline on the Modified Mini-Mental State examination (3MS), change score for the Trails B test time in the worse decile. Associations of sleep predictors and cognitive decline were examined with logistic regression and linear mixed models. After multivariable adjustment, higher levels of WASO and LWEP and lower SE were associated with an 1.4 to 1.5-fold increase in odds of clinically significant decline (odds ratio 95% confidence interval) Trails B test: SE < 70% versus SE ≥ 70%: 1.53 (1.07, 2.18); WASO ≥ 90 min versus WASO < 90 min: 1.47 (1.09, 1.98); eight or more LWEP versus fewer than eight: 1.38 (1.02, 1.86). 3MS: eight or more LWEP versus fewer than eight: 1.36 (1.09, 1.71), with modest relationships to linear change in cognition over time. PSQI was related to decline in Trails B performance (3 sec/y per standard deviation increase). CONCLUSIONS: Among older community-dwelling men, reduced sleep efficiency, greater nighttime wakefulness, greater number of long wake episodes, and poor self-reported sleep quality were associated with subsequent cognitive decline.

Medical planning and response for a nuclear detonation: a practical guide.

This article summarizes major points from a newly released guide published online by the Office of the Assistant Secretary for Preparedness and Response (ASPR). The article reviews basic principles about radiation and its measurement, short-term and long-term effects of radiation, and medical countermeasures as well as essential information about how to prepare for and respond to a nuclear detonation. A link is provided to the manual itself, which in turn is heavily referenced for readers who wish to have more detail.

Associations between sleep architecture and sleep-disordered breathing and cognition in older community-dwelling men: the Osteoporotic Fractures in Men Sleep Study.

OBJECTIVES: To examine the association between sleep architecture, sleep-disordered breathing, and cognition in older men. DESIGN: Population-based cross-sectional study. SETTING: Six clinical sites in the United States. PARTICIPANTS: Two thousand nine hundred nine community-dwelling men aged 67 and older who were not selected on the basis of sleep problems or cognitive impairment. MEASUREMENTS: Predictors were measured using in-home polysomnography: sleep architecture, nocturnal hypoxemia (any sleep time with arterial oxygen saturation <80%), apnea-hypopnea index (AHI), and arousal index. Cognitive outcomes were measured using the modified Mini-Mental State Examination (3MS), Trail-Making Test Part B (TMT-B), and the Digit Vigilance Test (DVT). RESULTS: Analyses adjusted for age, race, education, body mass index, lifestyle, comorbidities, and medication use showed that participants who spent less percentage of time in rapid eye movement (REM) sleep had lower levels of cognition; participants in the lowest quartile (<14.8%) took an average of 5.9 seconds longer on the TMT-B and 20.1 seconds longer on the DVT than those in the highest quartile (≥23.7%). Similarly, greater percentage of time spent in Stage 1 sleep was related to poorer cognitive function. Participants in the highest quartile of Stage 1 sleep (≥8.6%) had worse cognitive scores on average than those in the lowest quartile (<4.0%). Those with nocturnal hypoxemia took an average of 22.3 seconds longer to complete the DVT than those without, but no associations were found with 3MS or the TMT-B. CONCLUSION: Spending less percentage of time in REM sleep and greater percentage of time in Stage 1 sleep and having higher levels of nocturnal hypoxemia were associated with poorer cognition in older men. Further studies are needed to clarify the direction of these associations and to explore potential mechanisms.

Association of sleep characteristics and cognition in older community-dwelling men: the MrOS sleep study.

STUDY OBJECTIVES: To examine the association of objectively and subjectively measured sleep characteristics with cognition in older men. DESIGN: A population-based cross-sectional study. SETTING: 6 centers in the United States. PARTICIPANTS: 3,132 community-dwelling older men (mean age 76.4 ± 5.6 years). INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Objectively measured sleep predictors from wrist actigraphy were total sleep time (TST), sleep efficiency (SE), and wake after sleep onset (WASO). Subjective sleep predictors were self-reported poor sleep (Pittsburgh Sleep Quality Index [PSQI] > 5), excessive daytime sleepiness (EDS, Epworth Sleepiness Scale Score > 10), and TST. Cognitive outcomes were measured with the Modified Mini-Mental State examination (3MS), the Trails B test, and the Digit Vigilance Test (DVT). After adjustment for multiple potential confounders, WASO was modestly related to poorer cognition. Compared to those with WASO < 90 min, men with WASO ≥ 90 min took 6.1 sec longer to complete the Trails B test and had a 0.9-point worse 3MS score, on average (P<0.05). Actigraphically measured long sleepers had a slightly worse 3MS score compared to those with 7-8 h of sleep, but had similar Trails B and DVT completion times. Compared to those who self-reported sleeping 7-8 h, long sleepers (>8 h) on average took 8.6 sec more to complete the Trails B test, had a 0.6-point worse 3MS score, and took 46 sec longer to complete the DVT (P<0.05). PSQI and EDS were not independently related to cognitive outcomes. CONCLUSIONS: There were modest cross-sectional associations of WASO and self-reported long sleep with cognition among older community-dwelling men. EDS and PSQI were not related to cognition.

Sleep-disordered breathing, hypoxia, and risk of mild cognitive impairment and dementia in older women.

CONTEXT: Sleep-disordered breathing (characterized by recurrent arousals from sleep and intermittent hypoxemia) is common among older adults. Cross-sectional studies have linked sleep-disordered breathing to poor cognition; however, it remains unclear whether sleep-disordered breathing precedes cognitive impairment in older adults. OBJECTIVES: To determine the prospective relationship between sleep-disordered breathing and cognitive impairment and to investigate potential mechanisms of this association. DESIGN, SETTING, AND PARTICIPANTS: Prospective sleep and cognition study of 298 women without dementia (mean [SD] age: 82.3 [3.2] years) who had overnight polysomnography measured between January 2002 and April 2004 in a substudy of the Study of Osteoporotic Fractures. Sleep-disordered breathing was defined as an apnea-hypopnea index of 15 or more events per hour of sleep. Multivariate logistic regression was used to determine the independent association of sleep-disordered breathing with risk of mild cognitive impairment or dementia, adjusting for age, race, body mass index, education level, smoking status, presence of diabetes, presence of hypertension, medication use (antidepressants, benzodiazepines, or nonbenzodiazepine anxiolytics), and baseline cognitive scores. Measures of hypoxia, sleep fragmentation, and sleep duration were investigated as underlying mechanisms for this relationship. MAIN OUTCOME MEASURES: Adjudicated cognitive status (normal, dementia, or mild cognitive impairment) based on data collected between November 2006 and September 2008. RESULTS: Compared with the 193 women without sleep-disordered breathing, the 105 women (35.2%) with sleep-disordered breathing were more likely to develop mild cognitive impairment or dementia (31.1% [n = 60] vs 44.8% [n = 47]; adjusted odds ratio [AOR], 1.85; 95% confidence interval [CI], 1.11-3.08). Elevated oxygen desaturation index (≥15 events/hour) and high percentage of sleep time (>7%) in apnea or hypopnea (both measures of disordered breathing) were associated with risk of developing mild cognitive impairment or dementia (AOR, 1.71 [95% CI, 1.04-2.83] and AOR, 2.04 [95% CI, 1.10-3.78], respectively). Measures of sleep fragmentation (arousal index and wake after sleep onset) or sleep duration (total sleep time) were not associated with risk of cognitive impairment. CONCLUSION: Among older women, those with sleep-disordered breathing compared with those without sleep-disordered breathing had an increased risk of developing cognitive impairment.

Lactoferrin for the prevention of post-antibiotic diarrhoea.

Antibiotic-associated diarrhoea (AAD) is a common cause of morbidity and mortality. Older individuals in long-term care facilities are particularly vulnerable due to multisystem illnesses and the prevailing conditions for nosocomial infections. Lactoferrin, an antimicrobial protein in human breastmilk, was tested to determine whether it would prevent or reduce AAD, including Clostridium difficile in tube-fed long-term care patients. Thirty patients were enrolled in a randomized double-blind study, testing eight weeks of human recombinant lactoferrin compared to placebo for the prevention of antibiotic-associated diarrhoea in long-term care patients. Fewer patients in the lactoferrin group experienced diarrhoea compared to controls (p = 0.023). Based on the findings, it is concluded that human lactoferrin may reduce post-antibiotic diarrhoea.

Utility of sleep stage transitions in assessing sleep continuity.

STUDY OBJECTIVES: Sleep continuity is commonly assessed with polysomnographic measures such as sleep efficiency, sleep stage percentages, and the arousal index. The aim of this study was to examine whether the transition rate between different sleep stages could be used as an index of sleep continuity to predict self-reported sleep quality independent of other commonly used metrics. DESIGN AND SETTING: Analysis of the Sleep Heart Health Study polysomnographic data. PARTICIPANTS: A community cohort. MEASUREMENTS AND RESULTS: Sleep recordings on 5,684 participants were deemed to be of sufficient quality to allow visual scoring of NREM and REM sleep. For each participant, we tabulated the frequency of transitions between wake, NREM sleep, and REM sleep. An overall transition rate was determined as the number of all transitions per hour sleep. Stage-specific transition rates between wake, NREM sleep, and REM sleep were also determined. A 5-point Likert scale was used to assess the subjective experience of restless and light sleep the morning after the sleep study. Multivariable regression models showed that a high overall sleep stage transition rate was associated with restless and light sleep independent of several covariates including total sleep time, percentages of sleep stages, wake time after sleep onset, and the arousal index. Compared to the lowest quartile of the overall transition rate (<7.76 events/h), the odds ratios for restless sleep were 1.27, 1.42, and 1.38, for the second (7.77-10.10 events/h), third (10.11-13.34 events/h), and fourth (≥13.35 events/h) quartiles, respectively. Analysis of stage-specific transition rates showed that transitions between wake and NREM sleep were also independently associated with restless and light sleep. CONCLUSIONS: Assessing overall and stage-specific transition rates provides a complementary approach for assessing sleep continuity. Incorporating such measures, along with conventional metrics, could yield useful insights into the significance of sleep continuity for clinical outcomes.

Anthropometry in the prediction of sleep disordered breathing in HIV-positive and HIV-negative men.

BACKGROUND: Body mass index (BMI), waist circumference (WC) and neck circumference (NC) are important screening tools for sleep disordered breathing (SDB); however, the utility of anthropometry for this purpose has not been evaluated among HIV-positive patients. METHODS: HIV-negative men (n=60), HIV-positive men receiving highly active antiretroviral therapy (HIV-positive/HAART; n=58) and HIV-positive men not receiving HAART (HIV-positive/no HAART; n=41) from the Multicenter AIDS Cohort Study underwent a nocturnal sleep study and anthropomorphic assessment. Moderate-severe SDB was defined as an apnea/hypopnea event rate > or =15 episodes/h. Receiver operating characteristic (ROC) curves were used to compare the ability of different anthropometric measurements to predict SDB within each group. RESULTS: Moderate-severe SDB was found in 48% of men (HIV-negative [57%], HIV-positive/HAART [41%] and HIV-positive/no HAART [44%]). The performance of BMI, WC and NC to predict SDB was excellent among the HIV-negative men (ROC areas under the curve [AUCs] 0.83, 0.88 and 0.88, respectively) and fair among the HIV-positive/HAART group (AUC 0.71, 0.77 and 0.77, respectively). By contrast, these measurements had no predictive value in the HIV-positive/no HAART group (AUC 0.43, 0.41 and 0.45, respectively). Moreover, in the HIV-positive/no HAART group, moderate-severe SDB was independently associated with serum C-reactive protein > or =3.0 mg/l (odds ratio 6.9; P=0.04) and HIV RNA>10,000 copies/ml (odds ratio 7.1; P=0.05). CONCLUSIONS: BMI, WC and NC had a better predictive value for moderate-severe SDB in HIV-positive men compared with HIV-positive [corrected] men, and had no value among HIV-positive/no HAART men. Among this latter group, systemic inflammation might contribute to the pathogenesis of SDB.

Light exposure patterns in healthy older and young adults.

Aging is associated with an earlier timing of circadian rhythms and a shorter phase angle between wake time and the timing of melatonin secretion or the core body temperature nadir. Light has a phase-dependent effect on the circadian pacemaker, and modifications of habitual light exposure in older people could contribute to a change in the timing of circadian rhythms or in the phase angle of entrainment. In this study, we compare natural light exposure of community-dwelling older and young subjects studied at the same time of year, focusing on the pattern of light exposure across the waking day. We recorded light exposure data for 3 to 8 days from 22 older (aged 66.01 +/- 5.83) and 22 young subjects (aged 23.41 +/- 4.57), living at home on self-selected sleepwake schedules, and matched for time of year. All subjects were from New England (latitude 42.3 degrees N to 43 degrees N). We compared the percentage of the waking day spent by older and young subjects at 4 different light levels (from very dim to very bright). We compared hourly averaged light exposure data in each group according to clock time and with respect to each subject's daily sleepwake times. Although both age groups spent more than half of their waking hours in dim or moderate room light intensity (<100 lux), we found that the older subjects spent a significantly greater percentage of their waking day in the brighter light levels (> or =1000 lux); their hourly averaged light exposure levels were also significantly greater whether we examined the data with respect to absolute clock time, to wake time, or to bed time, and this was true across all seasons. We found that healthy older people were exposed to significantly higher levels of light throughout their waking day than young people. Differences in natural light exposure may contribute to the age-related phase advance of the circadian pacemaker and its later timing relative to the sleepwake cycle. This hypothesis should be explored further in carefully designed prospective studies.

Obstructive sleep apnea, insulin resistance, and steatohepatitis in severe obesity.

RATIONALE: Obstructive sleep apnea is associated with insulin resistance and liver injury. It is unknown whether apnea contributes to insulin resistance and steatohepatitis in severe obesity. OBJECTIVES: To examine whether sleep apnea and nocturnal hypoxemia predict the severity of insulin resistance, systemic inflammation, and steatohepatitis in severely obese individuals presenting for bariatric surgery. METHODS: We performed sleep studies and measured fasting blood glucose, serum insulin, C-reactive protein, and liver enzymes in 90 consecutive severely obese individuals, 75 women and 15 men, without concomitant diabetes mellitus or preexistent diagnosis of sleep apnea or liver disease. Liver biopsies (n = 20) were obtained during bariatric surgery. MEASUREMENTS AND MAIN RESULTS: Obstructive sleep apnea with a respiratory disturbance index greater than 5 events/hour was diagnosed in 81.1% of patients. The median respiratory disturbance index was 15 +/- 29 events/hour and the median oxygen desaturation during apneic events was 4.6 +/- 1.8%. All patients exhibited high serum levels of C-reactive protein, regardless of the severity of apnea, whereas liver enzymes were normal. Oxygen desaturation greater than 4.6% was associated with a 1.5-fold increase in insulin resistance, according to the homeostasis model assessment index. Histopathology data suggested that significant nocturnal desaturation might predispose to hepatic inflammation, hepatocyte ballooning, and liver fibrosis. Fasting blood glucose levels and steatosis scores were not affected by nocturnal hypoxia. There was no relationship between the respiratory disturbance index and insulin resistance or liver histopathology. CONCLUSIONS: Hypoxic stress of sleep apnea may be implicated in the development of insulin resistance and steatohepatitis in severe obesity.

Contribution of male sex, age, and obesity to mechanical instability of the upper airway during sleep.

Male sex, obesity, and age are risk factors for obstructive sleep apnea, although the mechanisms by which these factors increase sleep apnea susceptibility are not entirely understood. This study examined the interrelationships between sleep apnea risk factors, upper airway mechanics, and sleep apnea susceptibility. In 164 (86 men, 78 women) participants with and without sleep apnea, upper airway pressure-flow relationships were characterized to determine their mechanical properties [pharyngeal critical pressure under hypotonic conditions (passive Pcrit)] during non-rapid eye movement sleep. In multiple linear regression analyses, the effects of body mass index and age on passive Pcrit were determined in each sex. A subset of men and women matched by body mass index, age, and disease severity was used to determine the sex effect on passive Pcrit. The passive Pcrit was 1.9 cmH(2)O [95% confidence interval (CI): 0.1-3.6 cmH(2)O] lower in women than men after matching for body mass index, age, and disease severity. The relationship between passive Pcrit and sleep apnea status and severity was examined. Sleep apnea was largely absent in those individuals with a passive Pcrit less than -5 cmH(2)O and increased markedly in severity when passive Pcrit rose above -5 cmH(2)O. Passive Pcrit had a predictive power of 0.73 (95% CI: 0.65-0.82) in predicting sleep apnea status. Upper airway mechanics are differentially controlled by sex, obesity, and age, and partly mediate the relationship between these sleep apnea risk factors and obstructive sleep apnea.

Obesity and obstructive sleep apnea: pathogenic mechanisms and therapeutic approaches.

Obstructive sleep apnea is a common disorder whose prevalence is linked to an epidemic of obesity in Western society. Sleep apnea is due to recurrent episodes of upper airway obstruction during sleep that are caused by elevations in upper airway collapsibility during sleep. Collapsibility can be increased by underlying anatomic alterations and/or disturbances in upper airway neuromuscular control, both of which play key roles in the pathogenesis of obstructive sleep apnea. Obesity and particularly central adiposity are potent risk factors for sleep apnea. They can increase pharyngeal collapsibility through mechanical effects on pharyngeal soft tissues and lung volume, and through central nervous system-acting signaling proteins (adipokines) that may affect airway neuromuscular control. Specific molecular signaling pathways encode differences in the distribution and metabolic activity of adipose tissue. These differences can produce alterations in the mechanical and neural control of upper airway collapsibility, which determine sleep apnea susceptibility. Although weight loss reduces upper airway collapsibility during sleep, it is not known whether its effects are mediated primarily by improvement in upper airway mechanical properties or neuromuscular control. A variety of behavioral, pharmacologic, and surgical approaches to weight loss may be of benefit to patients with sleep apnea, through distinct effects on the mass and activity of regional adipose stores. Examining responses to specific weight loss strategies will provide critical insight into mechanisms linking obesity and sleep apnea, and will help to elucidate the humoral and molecular predictors of weight loss responses.