Effect of continuous positive airway pressure on C-reactive protein levels in sleep apnea: a meta-analysis

Efficacy of adenotonsillectomy on pediatric obstructive sleep apnea and related outcomes: A narrative review of current evidence

This review summarizes the current evidence in systematic reviews, meta-analysis and randomized controlled trials regarding adenotonsillectomy outcomes in pediatric obstructive sleep apnea (OSA). Adenotonsillectomy is effective in treating OSA in children without co-morbidities, despite postoperative residual OSA remained in roughly half of these children. For children with comorbidities such as Down syndrome, Prader-Willi syndrome, sickle cell disease, or cerebral palsy, adenotonsillectomy is less effective and associated with more postoperative complications than that in children without comorbidities. For other OSA-related outcomes, evidence from meta-analyses and randomized controlled trials confirm adenotonsillectomy results in improvement of subjective OSA-related outcomes (e.g. symptoms, behaviors, and quality of life), but the results in objective OSA-related outcomes (e.g. cardiometabolic parameters or neurocognitive functions) are inconsistent. Future studies should focus on randomized controlled trials comparing objective OSA-related outcomes and the long-term effects of adenotonsillectomy in children with OSA.

Potential Diagnostic and Monitoring Biomarkers of Obstructive Sleep Apnea-Umbrella Review of Meta-Analyses

Obstructive sleep apnea (OSA) is a prevalent, underdiagnosed disease that imposes a significant impact on the health and wellbeing of patients and a financial burden on individuals, their families, and society. Development of new methods of testing other than an overnight sleep study, such as measurement of serum or plasma biomarkers, may provide an easier diagnostic process to identify patients with OSA and allow earlier initiation of treatment, which might prevent serious comorbidities. We conducted a systematic review and quality assessment of available meta-analyses regarding potential diagnostic and monitoring biomarkers of obstructive sleep apnea. A total of 14 sets of candidate biomarkers displayed differences in levels or concentrations in OSA patients compared to non-OSA controls, and decreased after OSA treatment: CRP, IL-6, TNF-α, Il-8, HCY, ICAM-1, VCAM-1, VEGF, TC, LDLc, HDLc, TG, leptin, MDA, ALT, AST, IGF-1, adiponectin, and cortisol. This review summarizes the evidence for OSA-associated potential biomarkers and demonstrates that the quality of available studies, as measured by AMSTAR2, is often low and associated with a high risk of bias.

C-reactive protein in children with obstructive sleep apnea and effects of adenotonsillectomy

OBJECTIVE

C-reactive protein (CRP) is an important serum marker of inflammation associated with cardiovascular outcomes. This study aims to evaluate the association between CRP and childhood obstructive sleep apnea (OSA) and clarify the effects of adenotonsillectomy on serum CRP levels in children with OSA.

METHODS

Children with symptoms suggestive of OSA who underwent an overnight polysomnography were recruited from a tertiary medical center. Their serum CRP levels were measured. For children who underwent adenotonsillectomy for OSA treatment, polysomnography and serum high-sensitivity CRP (hs-CRP) level measurement were conducted after surgery.

RESULTS

This study included 326 children (mean age: 7.2 ± 3.0 years; boys: 67%). Children with apnea-hypopnea index (AHI) > 5 events/h had significantly higher hs-CRP levels than children with AHI of 1-5 events/h and AHI < 1 event/h [median (interquartile range): 0.08 (0.03-0.25) vs 0.03 (0.02-0.14) vs 0.04 (0.01-0.10), P < 0.001]. Log-transformed hs-CRP levels were positively associated with log AHI values (r = 0.2, P < 0.001). In multiple linear regression analysis, hs-CRP levels were independently associated with AHI; 101 children with OSA (ie, AHI > 1) underwent adenotonsillectomy. In children with OSA in the study cohort, a significant reduction of hs-CRP levels did not occur after surgery [from 0.07 (0.02-0.22) to 0.08 (0.03-0.17), P = 0.716]. In children with OSA having abnormal hs-CRP levels (ie, CRP > 1 mg/dL), hs-CRP levels significantly decreased after surgery [from 1.87 (1.11-2.78) to 0.20 (0.07-1.04), P = 0.043].

CONCLUSION

Children with OSA had increased hs-CRP levels. Children with OSA and abnormal hs-CRP levels exhibited significantly reduced hs-CRP levels following adenotonsillectomy.

Effect of Sleep Surgery on C-Reactive Protein Levels in Adults With Obstructive Sleep Apnea: A Meta-Analysis

OBJECTIVES/HYPOTHESIS

To evaluate associations between sleep surgery and CRP (C-reactive protein) levels in adults with obstructive sleep apnea (OSA).

STUDY DESIGN

Meta-analysis.

METHODS

Two authors independently searched PubMed, Medline, EMBASE, and Cochrane review databases until July 2019. The keywords used were sleep apnea, OSA, sleep apnea syndromes, surgery, C-reactive protein (CRP), and inflammatory markers. The effects of sleep surgery on CRP levels were examined using a random-effects model.

RESULTS

Nine studies with 277 patients were analyzed (mean age: 46.5 years; 92% men; mean sample size: 30.8 patients). The mean change in the apnea-hypopnea index (AHI) after surgery was significantly reduced by -21.1 (95% confidence interval [CI], -28.4 to -13.7) events/hr. Overall, sleep surgery resulted in a significant reduction of CRP levels in patients with OSA (standardized mean difference [SMD] = -0.39, 95% CI, -0.67 to -0.11). Patients with postoperative AHI reduction >20 events/hr achieved a greater reduction in CRP than those with AHI reduction <20 events/hr (SMD: -0.72 vs. -0.14, P for heterogeneity = .007). According to subgroup analysis, differences in the CRP levels after surgery were nonsignificant in the different countries (i.e., United States vs. other countries), CRP types (i.e., CRP vs. high-sensitivity CRP), surgical procedures (i.e., pharyngeal surgery vs. other surgical procedures), and follow-up period (i.e., <6 vs. >6 months).

CONCLUSIONS

Sleep surgery for OSA resulted in a significant reduction of CRP levels in adults. The beneficial effect of surgery on CRP levels is greater in patients with large improvement in OSA (i.e., AHI reduction >20 events/hr) after sleep surgery. Laryngoscope, 131:1180-1187, 2021.

Methodological Quality of Systematic Reviews and Meta-analyses Published in High-Impact Otolaryngology Journals

OBJECTIVE

To assess the methodological quality of intervention-focused systematic reviews (SRs) and meta-analyses (MAs) published in high-impact otolaryngology journals.

DATA SOURCES

Ovid Medline, Embase, and Cochrane Library.

REVIEW METHODS

A comprehensive search was performed for SR and MA citations from 2012 to 2017 in the 10 highest impact factor otolaryngology journals. Abstracts were screened to identify published manuscripts in which the authors indicated clearly that they were performing an SR or MA. Applying a modified typology of reviews, 4 reviewers characterized the review type as SR, MA, or another review type. A simplified version of the AMSTAR 2 (A MeaSurement Tool to Assess systematic Reviews 2) tool was used to assess the reporting and methodological quality of the SRs and MAs that were focused on interventions.

RESULTS

Search and abstract screening generated 499 manuscripts that identified themselves as performing an SR or MA. A substantial number (85/499, 17%) were review types other than SRs or MAs, including 34 (7%) that were literature reviews. In total, 236 SRs and MAs focused on interventions. Over 50% of these SRs and MAs had weaknesses in at least 3 of the 16 items in the AMSTAR 2, and over 40% had weaknesses in at least 2 of the 7 critical domains. Ninety-nine percent of SRs and MAs provided critically low confidence in the results of the reviews.

CONCLUSION

Intervention-focused SRs and MAs published in high-impact otolaryngology journals have important methodological limitations that diminish confidence in the results of these reviews.

Treatment of obstructive sleep apnea with CPAP improves chronic inflammation measured by neutrophil-to-lymphocyte ratio

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is associated with chronic inflammation likely triggered by nocturnal, intermittent hypoxemia and increased adrenergic tone. The neutrophil-to-lymphocyte ratio (NLR) was recently described as a measure of subclinical systemic inflammation. Studies on the effect of continuous positive airway pressure (CPAP) therapy in OSA on subclinical inflammation measured by NLR are lacking. We hypothesize that NLR levels would improve as chronic inflammation diminishes in patients with OSA treated with CPAP.

METHODS

We retrospectively reviewed patients in whom OSA was diagnosed and who were treated with CPAP therapy. Complete blood count (CBC) were obtained pretreatment and posttreatment for calculation of NLR, which was calculated by dividing the number of neutrophils by the number of lymphocytes. Patients with conditions known to affect NLR such as chronic infections, inflammatory diseases, active cardiovascular disease, and malignancies were excluded from the study. CPAP adherence downloads were obtained for all patients.

RESULTS

Out of 184 patients in whom OSA was diagnosed and who were treated with CPAP, 109 met our study criteria, including baseline polysomnogram, baseline and posttreatment CBC, and available adherence download. We compared the NLR before and after treatment with CPAP. There was a significant difference in NLR before and after treatment with CPAP (P < .0001). There was also a significant difference in apnea-hypopnea index before and after treatment (P < .0001). We also assessed the relationship between CPAP adherence (percentage of days used for > 4 hours) and the change in NLR. NLR decreased significantly in both the adherent (CPAP use ≥ 70% of days; P = .014) and nonadherent groups (CPAP use < 70% of days; P = .0003). Finally, we noticed a significant direct correlation between CPAP adherence beyond 70% and the change in NLR (ΔNLR) (P = .046) in patients who had ≥ 70% adherence with CPAP, which was not observed in patients with < 70% adherence.

CONCLUSIONS

The NLR may be a useful marker for monitoring improvement, as CPAP had a desirable effect on the chronic inflammation induced by OSA when measured by NLR in this study. Our results specifically suggest that the NLR values decrease significantly in patients using CPAP regardless of adherence, but with a more direct relationship in those who use it beyond 70% of days, at least 4 hours a day.

Is C-reactive protein elevated in obstructive sleep apnea? a systematic review and meta-analysis

Purpose: This study examined whether circulating C-reactive protein (CRP) is elevated in obstructive sleep apnoea (OSA) independent of the confounding effects of comorbidities, smoking, body mass index (BMI), age and gender. Methods: A systematic review of the literature was performed using PubMed, Embase and Cochrane databases from 1 January 1997 to 1 November 2017 using the key words obstructive sleep apnoea and C-Reactive protein to identify full text English language studies that compared CRP in adult non-smoking OSA participants without comorbidities and adult healthy non-smoking control participants matched for BMI, age and gender. Data from eligible studies were subjected to meta-analysis using RevMan version 5.3. Results: Five studies (219 OSA participants, 116 controls) met the selection criteria. The total standard mean difference for circulating high sensitivity CRP was 0.61 mg/dL higher in OSA participants than in control participants (confidence interval: 0.38 to 0.84, p < 0.00001), with low between-studies heterogeneity (df = 7, p = 0.16, I² = 33%) and minimal evidence of publication bias. Conclusions: CRP levels in non-smoking OSA participants without comorbidities were increased relative to levels in healthy matched non-smoking control participants, suggesting that pharyngeal or systemic inflammatory effects attributable to OSA may elevate CRP.

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.

Effect of continuous positive airway pressure on leptin levels in patients with obstructive sleep apnea: a meta-analysis

OBJECTIVES

Continuous positive airway pressure (CPAP) is an effective treatment for obstructive sleep apnea hypopnea syndrome (OSAHS), but previous studies assessing the effect of CPAP on leptin in patients with OSAHS yielded conflicting results. In this study, we conducted a meta-analysis to determine whether CPAP therapy could reduce serum leptin levels.

DATA SOURCES

Databases of PubMed, Elsevier, and SCI were thoroughly searched by 2 independent reviewers.

METHODS

RevMan (version 5.2) was used for data synthesis. Weighted mean difference (WMD) before and after CPAP therapy was calculated to estimate the effects of CPAP therapy.

RESULTS

A total of 11 studies involving 413 participants were included. Meta-analysis showed that the total WMD for leptin levels was 1.44 units (95% confidence interval: 1.11-1.77, P < .01) before and after CPAP therapy. Subgroup analysis exhibited that leptin was decreased within 3 days after the therapy, and it was further reduced within 1 to 3 months and beyond.

CONCLUSIONS

The results of our meta-analysis showed that CPAP could significantly reduce leptin levels in OSAHS patients without concomitant weight loss.

[Beneficial effect of continuous positive airway pressure therapy in obstructive sleep apnea syndrome]

Continuous positive airway pressure therapy is an evidence based therapy of obstructive sleep apnea syndrome. The effective treatment of obstructive sleep apnea can decrease sympaticotonia and, consequently, blood pressure. Furthermore, it can improve inflammatory and metabolic parameters resulting in a decreased cardiovascular risk. This article summarizes the positive effects of continuous positive airway pressure therapy on cardiovascular risk factors in obstructive sleep apnea syndrome.

Short duration of sleep is associated with elevated high-sensitivity C-reactive protein level in Taiwanese adults: a cross-sectional study

BACKGROUND

Elevated plasma levels of high-sensitivity C-reactive protein (hs-CRP) have been associated with increased adverse health outcomes. The aim of this study was to investigate the association of sleep duration with risk of elevated hs-CRP levels in Taiwanese adults.

METHODS

We examined the association between sleep duration and hs-CRP in 353 healthy adults recruited from the physical examination center at a regional hospital in southern Taiwan. Elevated hs-CRP was defined as a plasma level ≥ 0.20 mg/dL. Short sleep duration was defined as ≤ 5.5 h per day. Multiple logistic regression analysis was used to assess the association of short duration of sleep with elevated hs-CRP levels.

RESULTS

In this study, short duration of sleep (odds ratio [OR] = 2.20; 95% confidence interval [CI]: 1.11-4.30), aged 70 years or older (OR = 4.58; 95% CI: 1.70-12.66), menopause (OR = 2.81; 95% CI: 1.52-5.3), higher heart rate (OR = 1.38; 95% CI: 1.10-1.75), higher body mass index (OR = 1.20; 95% CI: 1.09-1.34), higher white blood cell count (OR = 1.38; 95% CI: 1.14-1.66), and higher uric acid level (OR = 1.31; 95% CI: 1.06-1.63) were significantly associated with an increased risk of elevated hs-CRP levels.

CONCLUSIONS

In this study of healthy Taiwanese adults, short duration of sleep was significantly associated with elevated hs-CRP levels. Activation of pro-inflammatory pathways might represent a mechanism by which short sleep duration affects health.

Impact of sleep-disordered breathing treatment on upper airway anatomy and physiology

Sleep-disordered breathing (SDB) is a major public health problem. Various anatomic, pathophysiologic, and environmental changes contribute to SDB. The successful treatment of SDB reverses many of these abnormal processes. The present article discusses the current clinical evidence that supports the reversibility and its potential application in the management of SDB. Continuous positive airway pressure reduces angiogenesis and inflammatory edema, increases pharyngeal size, and improves surrogate markers of vascular inflammation and tongue muscle fiber types. Mandibular advancement devices lead to favorable maxillary and mandibular changes, increase pharyngeal area, and improve hypertension. Uvulopalatopharyngoplasty increases posterior airway space and pharyngeal volume, reduces nasal and oral resistance, and lowers response to high CO2. Weight loss reduces nasopharyngeal collapsibility, critical closing pressure of the airway, apnea-hypopnea index, and improves oxygen saturations. Potential clinical benefits of these changes in the management of SDB and patient compliance with treatment are discussed.

Effects of continuous positive airway pressure therapy on systemic inflammation in obstructive sleep apnea: a meta-analysis

OBJECTIVES

Our meta-analysis was performed to estimate the effect of continuous positive airway pressure (CPAP) therapy on systemic inflammation in patients with obstructive sleep apnea (OSA).

METHODS

A comprehensive literature search of PubMed and EMBASE was performed for literature published up to January 2013. Standardized mean difference (SMD) was calculated to estimate the treatment effects of pre- and post-CPAP therapy.

RESULTS

A total of 35 studies involving 1985 OSA patients were included in the meta-analysis. Each study investigated one or more inflammatory markers: 24 studies on C-reactive protein (CRP), 16 studies on IL-6, 3 studies on IL-8, and 12 studies on tumor necrosis factor α (TNF-α). The results showed that the SMD (95% confidence interval [CI]) for CRP, IL-6, IL-8, and TNF-α were 0.452 (95% CI, 0.252-0.651), 0.299 (95% CI, 0.001-0.596), 0.645 (95% CI, 0.362-0.929), and 0.478 (95% CI, 0.219-0.736) in pre- and post-CPAP therapy, respectively. The subgroup analyses seemed to support better benefits with therapy duration of ≥3 months and more adequate compliance (≥4 h/night).

CONCLUSIONS

CPAP therapy could partially suppress systemic inflammation in OSA patients, and substantial differences were present among the various inflammatory markers.