Renata L. Riha

Tumour necrosis factor-α (−308) gene polymorphism in obstructive sleep apnoea–hypopnoea syndrome

Patients with obstructive sleep apnoea–hypopnoea syndrome (OSAHS) have elevated circulating levels of tumour necrosis factor (TNF)-α. The hypothesis in this study was that OSAHS might be associated with the TNF-α (−308A) gene polymorphism, which results in increased TNF-α production. This hypothesis was examined in OSAHS patients, their siblings and population controls. A total of 206 subjects were recruited. All underwent sleep studies and clinical review, and were subsequently classified as having OSAHS or not depending on apnoea–hypopnoea frequency, sex, age and symptoms. All subjects had blood collected and genotyping was performed on DNA extracted from peripheral leukocytes. Some 192 random UK blood donors were used as population controls. The results demonstrated a significant association for TNF-α (−308A) allele carriage with OSAHS (OR = 1.8; 95% Confidence interval: 1.18–2.75) when compared with population controls. Siblings with OSAHS were significantly more likely to carry the TNF-α (−308A) allele. In addition, 21 pairs of male siblings discordant for carriage of the −308A allele showed a significant level of discordance for the OSAHS phenotype. In conclusion, this study demonstrates an association of tumour necrosis factor-α (−308A) carriage with obstructive sleep apnoea–hypopnoea syndrome, suggesting that inflammation may be implicated in the pathogenesis of this condition.

Continuous positive airway pressure improves vascular function in obstructive sleep apnoea/hypopnoea syndrome: a randomised controlled trial

Background: The obstructive sleep apnoea/hypopnoea syndrome (OSAHS) is associated with hypertension and increased cardiovascular risk, particularly when accompanied by marked nocturnal hypoxaemia. The mechanisms of these associations are unclear. We hypothesised that OSAHS combined with severe nocturnal hypoxaemia causes impaired vascular function that can be reversed by continuous positive airways pressure (CPAP) therapy. Methods: We compared vascular function in two groups of patients with OSAHS: 27 with more than 20 4% desaturations/h (desaturator group) and 19 with no 4% and less than five 3% desaturations/h (non-desaturator group). In a randomised, double blind, placebo controlled, crossover trial, the effect of 6 weeks of CPAP therapy on vascular function was determined in the desaturator group. In all studies, vascular function was assessed invasively by forearm venous occlusion plethysmography during intra-arterial infusion of endothelium dependent (acetylcholine 5–20 μg/min and substance P 2–8 pmol/min) and independent (sodium nitroprusside 2–8 μg/min) vasodilators. Results: Compared with the non-desaturator group, patients with OSAHS and desaturations had reduced vasodilatation to all agonists (p = 0.007 for all). The apnoea/hypopnoea index and desaturation frequency were inversely related to peak vasodilatation with acetylcholine (r = −0.44, p = 0.002 and r = −0.43, p = 0.003) and sodium nitroprusside (r = −0.42, p = 0.009 and r = −0.37, p = 0.02). In comparison with placebo, CPAP therapy improved forearm blood flow to all vasodilators (p = 0.01). Conclusions: Patients with OSAHS and frequent nocturnal desaturations have impaired endothelial dependent and endothelial independent vasodilatation that is proportional to hypoxaemia and is improved by CPAP therapy. Impaired vascular function establishes an underlying mechanism for the adverse cardiovascular consequences of OSAHS.

Recommendations for the management of patients with obstructive sleep apnoea and hypertension

This article is aimed at addressing the current state-of-the-art in epidemiology, pathophysiology, diagnostic procedures and treatment options for appropriate management of obstructive sleep apnoea (OSA) in cardiovascular (in particular hypertensive) patients, as well as for the management of cardiovascular diseases (in particular arterial hypertension) in OSA patients. The present document is the result of work performed by a panel of experts participating in the European Union COST (Cooperation in Scientific and Technological research) Action B26 on OSA, with the endorsement of the European Respiratory Society and the European Society of Hypertension. In particular, these recommendations are aimed at reminding cardiovascular experts to consider the occurrence of sleep-related breathing disorders in patients with high blood pressure. They are also aimed at reminding respiration experts to consider the occurrence of hypertension in patients with respiratory problems at night.

Diabetes Mellitus Prevalence and Control in Sleep-Disordered Breathing: The European Sleep Apnea Cohort (ESADA) Study

BACKGROUND OSA is associated with an increased risk of cardiovascular morbidity. A driver of this is metabolic dysfunction and in particular type 2 diabetes mellitus (T2DM). Prior studies identifying a link between OSA and T2DM have excluded subjects with undiagnosed T2DM, and there is a lack of population-level data on the interaction between OSA and glycemic control among patients with diabetes. We assessed the relationship between OSA severity and T2DM prevalence and control in a large multinational population. METHODS We performed a cross-sectional analysis of 6,616 participants in the European Sleep Apnea Cohort (ESADA) study, using multivariate regression analysis to assess T2DM prevalence according to OSA severity, as measured by the oxyhemoglobin desaturation index. Patients with diabetes were identified by previous history and medication prescription, and by screening for undiagnosed diabetes with glycosylated hemoglobin (HbA1c) measurement. The relationship of OSA severity with glycemic control was assessed in diabetic subjects. RESULTS T2DM prevalence increased with OSA severity, from 6.6% in subjects without OSA to 28.9% in those with severe OSA. Despite adjustment for obesity and other confounding factors, in comparison with subjects free of OSA, patients with mild, moderate, or severe disease had an OR (95% CI) of 1.33 (1.04-1.72), 1.73 (1.33-2.25), and 1.87 (1.45-2.42) (P < .001), respectively, for prevalent T2DM. Diabetic subjects with more severe OSA had worse glycemic control, with adjusted mean HbA1c levels 0.72% higher in patients with severe OSA than in those without sleep-disordered breathing (analysis of covariance, P < .001). CONCLUSIONS Increasing OSA severity is associated with increased likelihood of concomitant T2DM and worse diabetic control in patients with T2DM.

Sleep-Disordered Breathing as a Risk Factor for Cerebrovascular Disease A Case-Control Study in Patients With Transient Ischemic Attacks

Background and Purpose— The evidence that obstructive sleep apnea/hypopnea (OSAH) is a risk factor for ischemic cerebrovascular disease is inconclusive. We explored this relationship in transient ischemic attack (TIA) patients because they are less likely than stroke patients to have OSAH as a consequence of cerebrovascular disease. Methods— We performed a case-control study among 86 patients with TIA from a hospital neurovascular clinic, matched for age (±5 years) and sex with controls from the referring local family practice registers. Results— Forty-nine of the 86 matched pairs were male and the body mass index was similar among cases and controls. The primary outcome measure, the apnea/hypopnea index [AHI=number of (apneas+hypopneas)/h slept, measured during overnight polysomnography and scored blind to case-control status], was the same for cases and controls (21/hour). However, the median number of 4% desaturations during sleep was slightly greater in the cases (12/hour) than controls (6/hour, P =0.04). There were the expected associations between TIA and higher fibrinogen levels (TIA 3.3, control 3.0 g/L, P =0.01), previous myocardial infarction (TIA 22, control 6%, P =0.007), a history of ever smoking (TIA 71, control 54%, P =0.01), hypertension (TIA 51, control 21%, P =0.001), and raised cholesterol (TIA 27, control 10%, P =0.01), with a weak trend for diabetes mellitus (TIA 10, control 6%, P =0.4). Conclusion— OSAH does not appear to be strongly associated with TIAs.

Survival of patients with biopsy-proven usual interstitial pneumonia and nonspecific interstitial pneumonia

This is the first Australian study to examine survival and clinical characteristics in biopsy-proven idiopathic interstitial pneumonia. A cohort of 70 patients from a single institution between January 1990 and December 1999 was reviewed. All patients were Caucasian, 23 (33%) female. Mean age±sd at diagnosis was 60±12 yrs for males and 54±14 yrs for females. A total 24% of patients had never smoked. The histopathological diagnoses were usual interstitial pneumonia (UIP) (n=59), nonspecific interstitial pneumonia (NSIP) (n=7), desquamative interstitial pneumonia (n=3) and acute interstitial pneumonia (n=11). Clinical and functional characteristics of the two main histological subgroups of UIP and NSIP showed significantly older patients in the UIP group and a significantly lower mean forced expiratory volume in one second (FEV1) in the NSIP group. Median survival for UIP was 78 months compared with 178 months for NSIP. No survival difference between treated and untreated patients with UIP was found. Multivariate analysis revealed smoking alone to be predictive of poorer survival. This study demonstrates the best median survival for usual interstitial pneumonia of available series and confirms a survival difference between usual interstitial pneumonia and nonspecific interstitial pneumonia. Furthermore, the reported results may have implications for treatment timing using conventional protocols currently recommended.

The European sleep apnoea database (ESADA) –report from 22 European sleep laboratories

The European Sleep Apnoea Database (ESADA) reflects a network of 22 sleep disorder centres in Europe enabled by a COST action B26 program. This ongoing project aims to describe differences in standard clinical care of patients with obstructive sleep apnoea (OSA) and to establish a resource for genetic research in this disorder. Patients with suspected OSA are consecutively included and followed up according to local clinical standards. Anthropometrics, medical history, medication, daytime symptoms and sleep data (polysomnography or cardiorespiratory polygraphy) are recorded in a structured web-based report form. 5103 patients (1426 females, age 51.8±12.6 years, 79.4% with AHI≥5 events·hr−1) were included from March 15, 2007 to August 1, 2009. Morbid obesity (BMI≥35 kg·m−2) was present in 21.1% of males and 28.6% of women. Cardiovascular, metabolic, and pulmonary comorbidities were frequent (49.1, 32.9 and 14.2%, respectively). Patients investigated with a polygraphic method had a lower AHI than those undergoing polysomnography (23.2±23.5 vs. 29.1±26.3 events·hour−1, p<0.0001). The ESADA is a rapidly growing multicentric patient cohort that enables unique outcome research opportunities and genotyping. The first cross sectional analysis reveals a high prevalence of cardiovascular and metabolic morbidity in patients investigated for OSAS.The European Sleep Apnoea Database (ESADA) reflects a network of 22 sleep disorder centres in Europe enabled by a COST action B26 programme. This ongoing project aims to describe differences in standard clinical care of patients with obstructive sleep apnoea (OSA) and to establish a resource for genetic research in this disorder. Patients with suspected OSA are consecutively included and followed up according to local clinical standards. Anthropometrics, medical history, medication, daytime symptoms and sleep data (polysomnography or cardiorespiratory polygraphy) are recorded in a structured web-based report form. 5,103 patients (1,426 females, mean±sd age 51.8±12.6 yrs, 79.4% with apnoea/hypopnoea index (AHI) ≥5 events·h−1) were included from March 15, 2007 to August 1, 2009. Morbid obesity (body mass index ≥35 kg·m−2) was present in 21.1% of males and 28.6% of females. Cardiovascular, metabolic and pulmonary comorbidities were frequent (49.1%, 32.9% and 14.2%, respectively). Patients investigated with a polygraphic method had a lower AHI than those undergoing polysomnography (23.2±23.5 versus 29.1±26.3 events·h−1, p<0.0001). The ESADA is a rapidly growing multicentre patient cohort that enables unique outcome research opportunities and genotyping. The first cross-sectional analysis reveals a high prevalence of cardiovascular and metabolic morbidity in patients investigated for OSA.

Cytokine gene polymorphisms in idiopathic pulmonary fibrosis.

Abstract

Management of obstructive sleep apnea in Europe

OBJECTIVES In Europe, the services provided for the investigation and management of obstructive sleep apnoea (OSA) varies from country to country. The aim of this questionnaire-based study was to investigate the current status of diagnostic pathways and therapeutic approaches applied in the treatment of OSA in Europe, qualification requirements of physicians involved in diagnosis and treatment of OSA, and reimbursement of these services. METHODS Two questionnaires were sent to 39 physicians in 22 countries in Europe. In order to standardize the responses, the questionnaire was accompanied by an example. RESULTS Sleep centers from 21 countries (38 physicians) participated. A broad consistency among countries with respect to the following was found: pathways included referral to sleep physicians/sleep laboratories, necessity for objective diagnosis (primarily by polysomnography), use of polygraphic methods, analysis of polysomnography (PSG), indications for positive airway pressure (PAP) therapy, application of standard continuous PAP (CPAP) therapy (100% with an CPAP/APAP ratio of 2.24:1), and the need (90.5%) and management of follow-up. Differences were apparent in reimbursement of the diagnostic procedures and follow-up, in the procedures for PAP titration from home APAP titration with portable sleep apnea monitoring (38.1%) up to hospital monitoring with PSG and APAP (85.7%), and in the qualification requirements of sleep physicians. CONCLUSIONS Management of OSA in different European countries is similar except for reimbursement rules, qualification of sleep specialists and procedures for titration of the CPAP treatment. A European network (such as the one accomplished by the European Cooperation in Science and Technology [COST] B26 Action) could be helpful for implementing these findings into health-service research in order to standardize management in a cost effective perspective.

The diagnostic method has a strong influence on classification of obstructive sleep apnea

Polygraphy (PG) and polysomnography (PSG) are used in clinical settings in Europe for diagnosing obstructive sleep apnea (OSA), but their equivalence in unselected clinical cohorts is unknown. We hypothesized that the method would affect both diagnostic outcomes and disease severity stratification. Data from 11 049 patients in the multi‐centre European Sleep Apnea Cohort (ESADA) with suspected OSA (male and female, aged 18–80 years) were used in two groups of patients to compare PG (n = 5745) and PSG (n = 5304). Respiratory events were scored using the 2007 American Association of Sleep Medicine (AASM) criteria. In subjects who underwent PSG, mean apnea–hypopnea index (AHI) using sleep time (AHIPSG 31.0 ± 26.1 h−1) and total analysed time (TAT) (AHITAT 24.7 ± 22.0 h−1) were higher than in subjects who underwent PG (AHIPG 22.0 ± 23.5 h−1) (P < 0.0001). The oxygen desaturation index (ODI) was lower in subjects investigated with PG (ODIPG 18.4 ± 21.7 h−1) compared to subjects investigated with PSG (ODIPSG 23.0 ± 25.3 h−1) but not different when the PSG was indexed by TAT (ODITAT 18.6 ± 21.4 h−1, P < 0.65). The proportion of patients with an AHI ≥ 15 was 64% in the subjects who underwent PSG and 47% in the subjects who underwent PG (P < 0.001). Overall, patients investigated using PG are likely to have a 30% lower AHI on average, compared to patients investigated by PSG. This study suggests that PG interpreted using standard guidelines results in underdiagnosis and misclassification of OSA. We advocate the development of PG‐specific guidelines for the management of OSA patients.