Obstructive sleep apnea and the effect of CPAP treatment on ischemia-modified albumin levels: a multi effect size meta-analysis with diagnostic test accuracy

Abstract

A close association of oxidative stress (OS) and ischemia-modified albumin (IMA) with obstructive sleep apnea (OSA) has been reported in the literature, but the results on IMA are ambiguous. We conducted a meta-analysis to evaluate the association of IMA with OSA and the effect of continuous positive airway pressure (CPAP) therapy on IMA in patients with OSA. Relevant studies were identified by searching PubMed and other databases in addition to manual searching of cross-references. Using random-effects model, the standardized mean differences (SMDs), pooled correlation coefficients and summary of diagnostic test accuracies were obtained with 95% confidence intervals (CIs). The meta-regression, sub-group and sensitivity analyses were performed to explore heterogeneity. The presence of publication bias was tested using funnel plot analysis followed by Begg's and Egger's tests for statistical signidicance. This meta-analysis finally included nine studies. When comparing with non-OSA controls, the OSA patients showed a significantly increased circulatory IMA levels (SMD = 1.15, p = 0.0001). And, this increase is even more pronounced in severe-OSA group as compared to mild-moderate OSA patients (SMD = 076, p = 0.0006). A decrease in post-CPAP treatment IMA was observed when compared with that of baseline values. Meta-analysis of correlations showed significant associations of IMA with polysomnographic parameters. The pooled diagnostic odds ratio and area under curve were 19.58 and 0.888 (Q* = 0.819), respectively. There was no evidence of publication bias for the association of IMA with OSA. This meta-analysis suggests that OSA is associated with significantly increased IMA levels which may indicate OS, ischemia and subclinical cardiovascular risk. In the diagnostic test accuracy meta-analysis, IMA showed good accuracy for OSA detection. However, further studies are required to establish its clinical utility.