Prevalence and risk factors of obstructive sleep apnea syndrome in a population of Delhi, India

A randomized controlled trial of nurse-led care for symptomatic moderate-severe obstructive sleep apnea

RATIONALE

Obstructive sleep apnea (OSA) is a prevalent disease. Often limited clinical resources result in long patient waiting lists. Simpler validated methods of care are needed.

OBJECTIVES

To demonstrate that a nurse-led model of care can produce health outcomes in symptomatic moderate-severe OSA not inferior to physician-led care.

METHODS

A randomized controlled multicenter noninferiority clinical trial was performed. Of 1,427 potentially eligible patients at 3 centers, 882 consented to the trial. Of these, 263 were excluded on the basis of clinical criteria. Of the remaining 619, 195 met home oximetry criteria for high-probability moderate-severe OSA and were randomized to 2 models of care: model A, the simplified model, using home autoadjusting positive airway pressure to set therapeutic continuous positive airway pressure (CPAP), with all care supervised by an experienced nurse; and model B, involving two laboratory polysomnograms to diagnose and treat OSA, with clinical care supervised by a sleep physician. The primary end point was change in Epworth Sleepiness Scale (ESS) score after 3 months of CPAP. Other outcome measures were collected.

MEASUREMENTS AND MAIN RESULTS

For the primary outcome change in ESS score, nurse-led management was no worse than physician-led management (4.02 vs. 4.15; difference, -0.13; 95% confidence interval: -1.52, 1.25) given a prespecified noninferiority margin of -2 for the lower 95% confidence interval. There were also no differences between both groups in CPAP adherence at 3 months or other outcome measures. Within-trial costs were significantly less in model A.

CONCLUSIONS

A simplified nurse-led model of care has demonstrated noninferior results to physician-directed care in the management of symptomatic moderate-severe OSA, while being less costly. Clinical trial registered with http://www.anzctr.org.au (ACTRN012605000064606).

Sleep-disordered breathing and type 2 diabetes: a report from the International Diabetes Federation Taskforce on Epidemiology and Prevention

Sleep-disordered breathing (SDB) has been associated with insulin resistance and glucose intolerance, and is frequently found in people with type 2 diabetes. SDB not only causes poor sleep quality and daytime sleepiness, but has clinical consequences, including hypertension and increased risk of cardiovascular disease. In addition to supporting the need for further research into the links between SDB and diabetes, the International Diabetes Federation Taskforce on Epidemiology and Prevention strongly recommends that health professionals working in both type 2 diabetes and SDB adopt clinical practices to ensure that a patient presenting with one condition is considered for the other.

Influence of sleep disturbance on quality of life of patients with epilepsy

The frequency of sleep disturbances in patients with epilepsy and their impact on quality of life (QoL) have been documented in a few reports, and the results are conflicting. We identified 124 consecutive epilepsy out-patients who visited the epilepsy out-patient clinics at the University Hospital of Alexandroupolis, the AHEPA Hospital in Thessaloniki and the Aeginitio Hospital in Athens. We measured excessive daytime sleepiness (EDS) with the Epworth Sleepiness Scale (ESS), obstructive sleep apnea (OSA) with the Sleep Apnea scale of the Sleep Disorders Questionnaire (SA-SDQ), and insomnia with the Athens Insomnia Scale (AIS). We evaluated quality of life by the Quality of Life in Epilepsy Inventory (QOLIE-31). EDS was found in 16.9% (21/124) of epileptic patients, OSA in 28.2% (35/124), and insomnia in 24.6% (30/122). In multivariate analysis, we found that insomnia was an independent negative factor for Total score (p<0.001), Overall QoL (p=0.002), Emotional well-being (p<0.001), Energy/fatigue (p<0.001), Cognitive functioning (p=0.04) and Social functioning (p=0.03), and OSA only for Cognitive functioning (p=0.01). According to our findings, EDS, OSA, and insomnia are frequent in epileptic patients. Epileptic patients with sleep disturbance, mainly insomnia, have significant QoL impairment.

An update on obstructive sleep apnea and the metabolic syndrome

PURPOSE OF REVIEW

Patients with obstructive sleep apnea are often overweight or obese, and they frequently exhibit metabolic aberrations, collectively known as the metabolic syndrome, an established cardiovascular risk factor. We review recent data on the relationship between obstructive sleep apnea and metabolic syndrome or its components, including abdominal obesity, insulin resistance, hypertension, and dyslipidemia.

RECENT FINDINGS

There is accumulating evidence for an independent association between obstructive sleep apnea and metabolic syndrome or its components. Recent epidemiologic and clinical data suggest a causal role of severe obstructive sleep apnea in development of hypertension, but findings for insulin resistance and dyslipidemia are controversial. Visceral obesity remains a confounding issue in analyses. Animal models and translational studies indicate that obstructive sleep apnea may promote metabolic dysfunction through cycles of intermittent hypoxia; proposed underlying pathophysiologic mechanisms include oxidative stress, sympathetic activation, and inflammation.

SUMMARY

There is suggestive evidence, but independent associations between obstructive sleep apnea and metabolic syndrome or its components are not fully established because of the confounding effect of obesity. Large randomized interventional trials are needed to identify any cause-effect relationship. Long-term follow-up studies would help to clarify the role of treatment of sleep apnea in reducing cardio-metabolic morbidity.

Usefulness of truncal obesity indices as predictive factors for obstructive sleep apnea syndrome

BACKGROUND

Optimization of the indications for nocturnal polysomnography in the diagnosis of obstructive sleep apnea syndrome (OSAS) could lead to significant reductions in health expenditure. To this end, we assessed the usefulness of truncal obesity measurements in the diagnosis of OSAS.

METHODS AND PROCEDURES

One hundred ninety-two patients (152 men and 40 women) referred to our clinic with suspected OSAS underwent a complete polysomnography study and their BMI and truncal obesity measurements were obtained.

RESULTS

Comparison of patients defined as snorers with OSAS patients, by means of the Student's t -test revealed significant differences in the truncal obesity parameters such as waist-to-hip ratio (0.94 vs. 0.98) and waist circumference (100.7 cm vs. 106.3 cm). We found no significant differences between BMI values in the two groups. Indices of truncal obesity were analyzed as predictive factors for OSAS using a multivariate logistic regression model that included variable sex, and in which waist-to-hip ratio, BMI, neck circumference, and age were analyzed as binary variables. According to this model, our patients' risk of suffering from OSAS was 2.6 times greater if the waist-to-hip ratio was >1 in men and >0.85 in women. The risk of OSAS was also increased if the patients were men or over 52 years of age.

DISCUSSION

Obtaining simple measurements such as those for truncal obesity may help prioritize the use of polysomnography in patients with a greater risk of OSAS. Our results suggest that BMI is not a good predictor of OSAS in a group of patients with a high BMI.

Obesity, and not obstructive sleep apnea, is responsible for increased serum hs-CRP levels in patients with sleep-disordered breathing in Delhi

OBJECTIVE

The present study was conducted to evaluate serum levels of high-sensitivity C-reactive protein (hs-CRP) in newly diagnosed patients with obstructive sleep apnea (OSA).

SUBJECTS AND METHODS

Between April 2005 and March 2006, a total of 231 consecutive adult habitual snorers underwent polysomnography (PSG) in the sleep laboratory. Ninety-seven subjects were found suitable for hs-CRP measurement after application of the following exclusion criteria: patients with diabetes mellitus, hypertension, coronary artery disease, acromegaly, hypothyroidism, chronic renal failure, congestive cardiac failure, or smoking history, patients who were pregnant, on steroid treatment, on hormone replacement therapy, or with chronic use of drugs such as non-steroidal anti-inflammatory drugs, oral anticoagulants and lipid-lowering drugs and patients having undergone upper airway surgery. Patients were classified as apneic [apnea-hypopnea index (AHI)>5], obese non-apneic [body mass index (BMI)>25, AHI<5] and non-obese non-apneic (BMI<25, AHI<5). C-reactive protein levels were measured in stored sera by high-sensitivity enzyme immunoassay (Biocheck, Inc. Foster City, CA, USA). After checking normality with the Kolmogorov-Smirnov test and using a square-root transformation, Pearson's and partial correlation coefficients were calculated for identified risk factors and confounders. A multiple linear regression model was used to identify variables that were independently associated with hs-CRP.

RESULTS

The mean serum levels of hs-CRP were found to be 0.25+/-0.23, 0.58+/-0.55, and 0.51+/-0.37 mg/dl in non-obese non-apneics (n=23), obese non-apneics (n=45) and apneics (obese and non-obese, n=29), respectively. Pearson's correlation coefficient of hs-CRP with BMI was found to be 0.25 (p=0.01), and with AHI 0.16 (p=0.12). Partial correlation analysis showed that hs-CRP levels correlated significantly with BMI after adjustment for AHI and age (r=0.22, p=0.03), while correlation with disease severity as assessed by AHI after adjustment for BMI and age was not significant (r=0.10, p=0.33). After stepwise multiple linear regression, only BMI was found to be significantly associated with serum hs-CRP levels (beta=0.02, p=0.01).

CONCLUSIONS

In this first comprehensive cross-sectional study on Indian subjects, we found that obesity, and not obstructive sleep apnea, is associated with elevated serum levels of hs-CRP. No independent correlation was found between severity of OSA and hs-CRP in the present study.

Investigating the metabolic capabilities of Mycobacterium tuberculosis H37Rv using the in silico strain iNJ661 and proposing alternative drug targets

Background:

Mycobacterium tuberculosis continues to be a major pathogen in the third world, killing almost 2 million people a year by the most recent estimates. Even in industrialized countries, the emergence of multi-drug resistant (MDR) strains of tuberculosis hails the need to develop additional medications for treatment. Many of the drugs used for treatment of tuberculosis target metabolic enzymes. Genome-scale models can be used for analysis, discovery, and as hypothesis generating tools, which will hopefully assist the rational drug development process. These models need to be able to assimilate data from large datasets and analyze them.

Results:

We completed a bottom up reconstruction of the metabolic network of Mycobacterium tuberculosis H37Rv. This functional in silico bacterium, iNJ661, contains 661 genes and 939 reactions and can produce many of the complex compounds characteristic to tuberculosis, such as mycolic acids and mycocerosates. We grew this bacterium in silico on various media, analyzed the model in the context of multiple high-throughput data sets, and finally we analyzed the network in an 'unbiased' manner by calculating the Hard Coupled Reaction (HCR) sets, groups of reactions that are forced to operate in unison due to mass conservation and connectivity constraints.

Conclusion:

Although we observed growth rates comparable to experimental observations (doubling times ranging from about 12 to 24 hours) in different media, comparisons of gene essentiality with experimental data were less encouraging (generally about 55%). The reasons for the often conflicting results were multi-fold, including gene expression variability under different conditions and lack of complete biological knowledge. Some of the inconsistencies between in vitro and in silico or in vivo and in silico results highlight specific loci that are worth further experimental investigations. Finally, by considering the HCR sets in the context of known drug targets for tuberculosis treatment we proposed new alternative, but equivalent drug targets.

Obesity, and not obstructive sleep apnea, is responsible for metabolic abnormalities in a cohort with sleep-disordered breathing

OBJECTIVE

To assess the profile of metabolic abnormalities in subjects with obstructive sleep apnea (OSA).

PATIENTS AND METHODS

In a case-control study conducted in two years, from April 2003 to March 2005, data obtained from polysomnography study, lipid profile, fasting blood sugar, serum insulin, insulin resistance, leptin and adiponectin levels, were compared between the various groups. Included in the study were OSA subjects from a sleep laboratory and matched controls from the community. Those with recent myocardial infarction, upper airway surgery, class III/IV heart failure, pregnancy, acromegaly, chronic renal failure, or who were on treatment for hyperthyroidism, on systemic steroid treatment, or on hormonal replacement therapy, were excluded from the study.

RESULTS

Forty apneic obese subjects (AHI=32.19, range 13-52.75) were compared with 40 non-apneic obese controls (AHI=1.3, range 0-2.45) and 40 normal weight control subjects (AHI=0.7, range 0-1). No significant difference was noted in levels of fasting blood sugar, insulin resistance (obese apneics 61.9, obese controls 47.8, non-obese controls 19.1), leptin (obese apneics 10.65 microg/L, obese controls 8.52 microg/L, non-obese controls 2.83 microg/L) or adiponectin (obese apneics 4959.3 ng/ml, obese controls 5706 ng/ml, non-obese controls 7412 ng/ml) in the OSA group compared to obese controls.

CONCLUSIONS

OSA has no independent association with lipid abnormalities, insulin resistance, serum leptin and adiponectin levels. In multivariate analysis, obesity was the major determinant of metabolic abnormalities in this cohort.