Association of metabolic factors with high-sensitivity C-reactive protein in patients with sleep-disordered breathing. Eur Arch Otorhinolaryngol. 2013;270:749-754. [PMID: 23053373 DOI: 10.1007/s00405-012-2191-4]

Impact of Obstructive Sleep Apnea and Continuous Positive Airway Pressure Treatment on Dry Eye Disease: A Systematic Review and Meta-Analysis

Obstructive sleep apnea (OSA) has been reported to influence the ocular surface and may lead to dry eye disease (DED). Continuous positive airway pressure (CPAP) is the first-line conservative treatment for OSA. However, CPAP might also have mask-related side effects that could deteriorate DED simultaneously. This study investigated the impact of OSA on DED (Aim 1), and CPAP on DED (Aim 2). Five databases were searched for articles published up to May, 2024. OSA severity, CPAP usage, and DED parameters, including tear breakup time (TBUT), Schirmer test, Ocular Surface Disease Index (OSDI), and Corneal Fluorescence Staining Score (CFS), were analyzed. For Aim 1, the random-effects model was used for meta-analysis, and the leave-one-out method was used for sensitivity analysis. For Aim 2, a narrative synthesis with critical appraisal of the literature was performed. Eleven studies with 1,526 patients for Aim 1 and three studies with 180 patients for Aim 2 were included. For Aim 1, OSA patients had poorer dry eye profiles of TBUT, Schirmer test, and OSDI when compared to non-OSA patients. For Aim 2, it seemed that those wearing CPAP for less than half a year did not have enough improvement in dry eye status. Instead, those wearing CPAP for at least a year reached greater therapeutic effects for OSA and DED. We concluded that OSA patients may suffer from poorer dry eye condition compared to non-OSA patients. Besides, wearing CPAP for long enough duration (at least 1 year) seemed to have better improvement in DED.

Sleep Related Breathing Disorders and Inflammation - The Missing Link? A Cohort Study Evaluating the Interaction of Inflammation and Sleep Related Breathing Disorders and Effects of Treatment

Introduction

Sleep related breathing disorders (SRBD) are associated with both obesity and systemic inflammation. While the relationship between obesity and SRBD is established, the causality between inflammation and SRBD remains unclear. In this study we investigated the relation between SRBD and C-reactive protein (CRP) as a parameter of inflammation and the influence of SRBD treatment on CRP with additional regard to changes in metabolic and cardiovascular parameters.

Methods

Polysomnography (PSG) and laboratory data of patients diagnosed with SRBD over a period of 5 years were prospectively collected in a database and retrospectively analysed regarding the association of SRBD (according to apnoea-hypopnoea- index (AHI), duration of events and extent of desaturation) to CRP, blood pressure, cholesterol, fasting plasma glucose, HbA1c, quality of life measured via a visual analogue scale (VAS 0–100%), and the effects of SRBD therapy on these parameters.

Results

716 patients were included in the study, 171 with mild SRBD (AHI ≥5 to <15/h), 209 with moderate SRBD (AHI 15 to <30/h), 336 with severe SRBD (AHI ≥30/h). Results according to severity of SRBD. Severe SRBD was significantly associated with elevated levels of CRP (3.7 [1.8–7.0] mg/l, vs. moderate (p = 0.001), and mild SRBD (p<0.001), and higher prevalence of hypertension as compared to moderate and mild SRBD (p<0.001, respectively). Results in highly successful treatment. If SRBD treatment was highly successful (AHI <5/h), CRP and quality of life improved significantly (p = 0.001 and p = 0.002), as did blood pressure (p<0.001 for systolic and diastolic values), although BMI increased (p<0.001). Results in partially successful treatment. If success was defined as reduction of AHI of ≥50%, CRP also decreased (p<0.001), as did blood pressure (p<0.001). Again, BMI increased (p<0.001).

Conclusion

This is the first study to show an association of SRBD and CRP independently of BMI in a large cohort. The SRBD therapy-induced CRP decrease was not associated with BMI changes or metabolic changes but rather with the magnitude of AHI improvement.

Obstructive sleep apnea syndrome and cardiovascular disease: The influence of C-reactive protein

Obstructive sleep apnea syndrome (OSAS) is a common medical condition, associated with atherosclerosis and cardiovascular disease (CVD). The underlying pathophysiologic mechanisms of this association have not been completely understood and may be multifactorial in origin. A number of studies suggest that inflammatory processes have emerged critical in the pathogenesis of CVD in OSAS. A range of circulating inflammatory molecules has been identified and measured, with a view to assess inflammation and predict vascular damage risk, such as plasma cytokines, adhesion molecules, and C-reactive protein (CRP). CRP is a relevant marker worthy of further study, because not only is elevated in patients with OSAS, but also is rapidly becoming a risk factor for cardiac disease. Furthermore, in selected OSAS patients, aggressive treatment of the disorder may lead to retarding or even improvement of CVD progression. However, still there is a debate on the true correlation between CRP and OSAS, as well as the clinical effect of any reduction after OSAS treatment. Further research is required to define those OSAS patients who will have a considerable reduction with treatment, as well as to understand the significance of the interaction between cardiovascular risk factor and CRP reduction in patients with OSAS.

Sleep-disordered breathing and C-reactive protein in obese children and adolescents

PURPOSE

Sleep-disordered breathing (SDB) is common among overweight and obese children. It is a risk factor for several health complications, including cardiovascular disease. Inflammatory processes leading to endothelial dysfunction are a possible mechanism linking SDB and cardiovascular disease. Elevated C-reactive protein (CRP) is a risk factor for cardiovascular disease and is independently correlated with obstructive sleep apnea syndrome (OSAS) in adults. Our goal is to evaluate the relationship between CRP and OSAS in overweight and obese children and adolescents.

METHODS

One hundred and twenty children were prospectively studied (85 without OSAS, 20 mild OSAS, 15 moderate-to-severe OSAS). All subjects underwent polysomnography, and a blood sample was taken to determine CRP levels.

RESULTS

No significant differences were found in CRP between subjects with or without OSAS, and no correlations were found between CRP and OSAS severity, despite the relationship between CRP and BMI (r = 0.21, p = 0.015) and between CRP and fat mass (r = 0.31, p < 0.001).

CONCLUSION

These results suggest that CRP levels are correlated with the level of obesity but are not influenced by SDB in obese children and adolescents; hence, this in contrast to that in adult population.

Obstructive sleep apnea syndrome is associated with metabolic syndrome and inflammation

Obstructive sleep apnea (OSA) is an independent risk factor for cardiovascular morbidity and mortality. However, the underlying mechanism is unclear. In this cross-sectional study, we investigated the influence of OSA on metabolic syndrome (MetS) and inflammation, which were considered as cardiovascular risks. A total of 144 consecutive male patients who underwent standard polysomnography were enrolled. Fasting blood samples were obtained from all patients for glucose, high-sensitivity C-reactive protein (hs-CRP) and lipids measurement. A metabolic score was established as the total number of the positive diagnostic criteria of metabolic syndrome for each patient. Systolic blood pressure, diastolic blood pressure, fasting glucose, hs-CRP and metabolic score significantly increased with the aggravation of OSA severity. Metabolic score increased from 1.74 ± 1.20 to 2.89 ± 0.99 with OSA severity (p = 0.000). hs-CRP increased from 0.68 (0.43-1.10) to 1.44 (0.62-4.02) mg/L with OSA severity (p = 0.002). After adjustment for confounders, apnea-hypopnea index and body mass index (BMI) were the major contributing factors for metabolic score (β = 0.257, p = 0.003 and β = 0.344, p = 0.000, respectively), lowest O2 saturation and BMI were the independent predictors of hs-CRP (β = -0.255, p = 0.003 and β = 0.295, p = 0.001, respectively). OSA is independently associated with sum of metabolic components and hs-CRP.

Pathophysiologic mechanisms of cardiovascular disease in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent sleep disorder, characterized by repeated disruptions of breathing during sleep. This disease has many potential consequences including excessive daytime sleepiness, neurocognitive deterioration, endocrinologic and metabolic effects, and decreased quality of life. Patients with OSAS experience repetitive episodes of hypoxia and reoxygenation during transient cessation of breathing that provoke systemic effects. Furthermore, there may be increased levels of biomarkers linked to endocrine-metabolic and cardiovascular alterations. Epidemiological studies have identified OSAS as an independent comorbid factor in cardiovascular and cerebrovascular diseases, and physiopathological links may exist with onset and progression of heart failure. In addition, OSAS is associated with other disorders and comorbidities which worsen cardiovascular consequences, such as obesity, diabetes, and metabolic syndrome. Metabolic syndrome is an emerging public health problem that represents a constellation of cardiovascular risk factors. Both OSAS and metabolic syndrome may exert negative synergistic effects on the cardiovascular system through multiple mechanisms (e.g., hypoxemia, sleep disruption, activation of the sympathetic nervous system, and inflammatory activation). It has been found that CPAP therapy for OSAS provides an objective improvement in symptoms and cardiac function, decreases cardiovascular risk, improves insulin sensitivity, and normalises biomarkers. OSAS contributes to the pathogenesis of cardiovascular disease independently and by interaction with comorbidities. The present review focuses on indirect and direct evidence regarding mechanisms implicated in cardiovascular disease among OSAS patients.