Diagnosis of obstructive sleep apnea by peripheral arterial tonometry: meta-analysis.

IMPORTANCE: Efficient diagnosis and early treatment of obstructive sleep apnea may help prevent the development of related morbidity and mortality. Compared with polysomnography (PSG), ambulatory sleep study devices offer the possibility of an accurate diagnosis with convenience and low cost. OBJECTIVE: To assess the correlation between sleep indexes measured by a portable sleep-testing device (peripheral arterial tonometry [PAT]) and those measured by PSG. DATA SOURCES: We searched PubMed, MEDLINE, the Cochrane Trial Registry (through May 2013), and relevant article bibliographies. STUDY SELECTION: Systematic review and meta-analysis of studies assessing correlation of sleep indexes between PAT devices and PSG in adults (aged >18 years). Included studies provided a bivariate correlation coefficient for sleep indexes, specifically the respiratory disturbance index (RDI), apnea-hypopnea index (AHI), and oxygen desaturation index (ODI). DATA EXTRACTION AND SYNTHESIS: Included studies were reviewed by 2 independent reviewers. Reported correlation values for the RDI, AHI, and ODI between a commercially available PAT device (WatchPAT) and PSG were systematically reviewed. A comprehensive meta-analysis software package was used for statistical analysis. MAIN OUTCOMES AND MEASURES: Assessment of the correlation between PAT and PSG as measured by AHI, RDI, and ODI. RESULTS: Fourteen studies met inclusion criteria and had data suitable for pooling (909 patients). Of these, 13 studies had blinded study designs, with PAT and PSG conducted simultaneously in the home or the laboratory setting. One study contained 2 trial phases for the same patient group (n = 29), one laboratory based and the other home based, which were analyzed separately. One study contained 2 different study groups based on age. Overall, correlation of the RDI and AHI was high (r = 0.889 [95% CI, 0.862-0.911]; P < .001). Studies comparing the RDI between PAT and PSG had a combined correlation of 0.879 (95% CI, 0.849-0.904; P < .001); those comparing the AHI, 0.893 (0.857-0.920; P < .001); and those comparing the ODI, 0.942 (0.894-0.969; P < .001). Analysis of publication bias revealed a nonsignificant Egger regression intercept. CONCLUSIONS AND RELEVANCE: Respiratory indexes calculated using PAT-based portable devices positively correlated with those calculated from the scoring of PSG. Strengthened by the blinded design of most of the included studies, this technology represents a viable alternative to PSG for confirmation of clinically suspected sleep apnea.

Functional and molecular effects of arginine butyrate and prednisone on muscle and heart in the mdx mouse model of Duchenne Muscular Dystrophy.

BACKGROUND: The number of promising therapeutic interventions for Duchenne Muscular Dystrophy (DMD) is increasing rapidly. One of the proposed strategies is to use drugs that are known to act by multiple different mechanisms including inducing of homologous fetal form of adult genes, for example utrophin in place of dystrophin. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we have treated mdx mice with arginine butyrate, prednisone, or a combination of arginine butyrate and prednisone for 6 months, beginning at 3 months of age, and have comprehensively evaluated the functional, biochemical, histological, and molecular effects of the treatments in this DMD model. Arginine butyrate treatment improved grip strength and decreased fibrosis in the gastrocnemius muscle, but did not produce significant improvement in muscle and cardiac histology, heart function, behavioral measurements, or serum creatine kinase levels. In contrast, 6 months of chronic continuous prednisone treatment resulted in deterioration in functional, histological, and biochemical measures. Arginine butyrate-treated mice gene expression profiling experiments revealed that several genes that control cell proliferation, growth and differentiation are differentially expressed consistent with its histone deacetylase inhibitory activity when compared to control (saline-treated) mdx mice. Prednisone and combination treated groups showed alterations in the expression of genes that control fibrosis, inflammation, myogenesis and atrophy. CONCLUSIONS/SIGNIFICANCE: These data indicate that 6 months treatment with arginine butyrate can produce modest beneficial effects on dystrophic pathology in mdx mice by reducing fibrosis and promoting muscle function while chronic continuous treatment with prednisone showed deleterious effects to skeletal and cardiac muscle. Our results clearly indicate the usefulness of multiple assays systems to monitor both beneficial and toxic effects of drugs with broad range of in vivo activity.