The role of severity of obstructive sleep apnea measured by apnea-hypopnea index in predicting compliance with pressure therapy, a meta-analysis.

Obstructive sleep apnea (OSA) is associated with diabetes, hypertension, stroke, coronary artery disease, and premature death. Positive airway pressure (PAP) is the mainstay of therapy. Despite its effective treatment with PAP therapy, noncompliance remains high. Many factors determine compliance. The role of severity of OSA measured by the apnea-hypopnea index (AHI) remains controversial. Meta-analysis of studies examining this role of AHI was performed. A systematic review of the medical literature was conducted using PubMed and Cochrane library by utilizing different combinations of key words: sleep apnea, AHI, compliance, and nonadherence. Inclusion criteria were English articles; Studies with adult population; with 2 groups of patients (compliant and noncompliant); Studies utilizing objective definition of compliance (PAP usage of >4 hours per night for 70% of days or usage >5 d/wk and for >4 hours per night). Studies were analyzed by standard methods of meta-analysis. The studies were heterogeneous for AHI; therefore, the random effect model was used. Six hundred forty-one manuscripts were found. Of these, 230 were found to be appropriate for full text evaluation. Thirty-one met inclusion criteria. Twelve of these studies used objective criteria for PAP compliance and were hence included in meta-analysis. All the subjects had OSA determined by polysomnography, for whom PAP was employed. Compliance to PAP therapy was evaluated after a period of time ranging from 4 weeks to 8 years. There were 1438 subjects included in the meta-analysis; 886 subjects were PAP compliant, whereas 552 subjects were noncompliant. A greater AHI was found in PAP compliant patients. The mean difference between compliant and noncompliant groups was 5.9 (95% confidence interval: 0.19-11.67, P < 0.05). Patients with mild OSA are less likely to be compliant with PAP therapy. These patients should receive aggressive management particularly at the start of therapy with close follow-up to increase compliance.

Serum inflammatory markers in obstructive sleep apnea: a meta-analysis.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) has been linked to and is associated with increased cardiovascular and cerebrovascular morbidity. Ongoing inflammatory responses play an important role in this association. Multiple small size studies addressing the profile of the inflammatory markers in OSA are available therefore we performed a meta-analysis. METHODS: Systematic review of medical literature was conducted using PubMed, Cochrane, and EMBASE databases from 1968 to 2011 by utilizing the key words obstructive sleep apnea, C-Reactive protein, tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin 8 (IL-8), intercellular adhesion molecule (ICAM), vascular cell adhesion molecule (VCAM) and Selectins. Inclusion criteria were: full text English articles; studies with adult population; reported values for at least one of the markers of interest; with at least two separate groups (subjects with OSA and control group); OSA was defined as AHI of ≥ 5/h. RESULTS: Five hundred and twelve studies were reviewed for inclusion with 51 studies pooled for analysis (30 studies for CRP, 19 studies for TNF-α, 8 studies for ICAM, 18 studies for IL-6, six studies for VCAM and 5 studies for Selectins). The levels of inflammatory markers were higher in patients with OSA compared to control group. Standardized pooled Mean differences were calculated to be 1.77 for CRP, 1.03 for TNF-α, 2.16 for IL-6, 4.22 for IL-8, 2.93 for ICAM, 1.45 for Selectins and 2.08 for VCAM. CONCLUSIONS: In this meta-analysis, the levels of systemic inflammatory markers were found to be higher in OSA patients compared to control subjects.

Patients with obstructive sleep apnea display increased carotid intima media: a meta-analysis.

Background. Obstructive sleep apnea (OSA) is associated with coronary artery disease. Intermittent hypoxia associated with OSA increases sympathetic activity and may cause systemic inflammation, which may contribute to atherosclerosis leading to an increase in the size of carotid intima media thickness (CIMT). Methods. PubMed and Cochrane library were reviewed by utilizing different combinations of key words: sleep apnea, carotid disease, intima media thickness, and carotid atherosclerosis. Inclusion criteria were English articles; studies with adult population with OSA and without OSA; CIMT recorded by ultrasound in mean and standard deviation or median with 95% confidence interval; and OSA defined as apnea hypopnea index of ≥5/h. A total of 95 studies were reviewed for inclusion, with 16 studies being pooled for analysis. Results. Ninety-five studies were reviewed, while 16 studies were pooled for analysis; since some studies have more than one data set, there were 25 data sets with 1415 patients being pooled for meta-analysis. All studies used ultrasound to measure CIMT. CIMT standardized difference in means ranged from -0.883 to 8.01. The pooled standardized difference in means was 1.40 (lower limit 0.996 to upper limit 1.803, (P < 0.0001). Conclusion. Patients with OSA appear to have increased CIMT suggestive of an atherosclerotic process.