• Home sleep apnea testing: comparison of manual and automated scoring across international sleep centers.

      Magalang, Ulysses J; Johns, Jennica N; Wood, Katherine A; Mindel, Jesse W; Lim, Diane C; Bittencourt, Lia R; Chen, Ning-Hung; Cistulli, Peter A; Gíslason, Thorarinn; Arnardottir, Erna S; et al. (Springer Heidelberg, 2019-03)
      To determine the agreement between the manual scoring of home sleep apnea tests (HSATs) by international sleep technologists and automated scoring systems. Fifteen HSATs, previously recorded using a type 3 monitor, were saved in European Data Format. The studies were scored by nine experienced technologists from the sleep centers of the Sleep Apnea Global Interdisciplinary Consortium (SAGIC) using the locally available software. Each study was scored separately by human scorers using the nasal pressure (NP), flow derived from the NP signal (transformed NP), or respiratory inductive plethysmography (RIP) flow. The same procedure was followed using two automated scoring systems: Remlogic (RLG) and Noxturnal (NOX). The intra-class correlation coefficients (ICCs) of the apnea-hypopnea index (AHI) scoring using the NP, transformed NP, and RIP flow were 0.96 [95% CI 0.93-0.99], 0.98 [0.96-0.99], and 0.97 [0.95-0.99], respectively. Using the NP signal, the mean differences in AHI between the average of the manual scoring and the automated systems were - 0.9 ± 3.1/h (AHI There is very strong agreement in the scoring of the AHI for HSATs between the automated systems and experienced international technologists. Automated scoring of HSATs using commercially available software may be useful to standardize scoring in future endeavors involving international sleep centers.
    • Obesity modulates the association between sleep apnea treatment and CHI3L1 levels but not CHIT1 activity in moderate to severe OSA: an observational study.

      Teitsdottir, Unnur Dilja; Arnardottir, Erna Sif; Bjornsdottir, Erla; Gislason, Thorarinn; Petersen, Petur Henry; 1 Faculty of Medicine, Department of Biochemistry and Molecular Biology, Biomedical Center, University of Iceland, Reykjavik, Iceland. udt1@hi.is. 2 Faculty of Medicine, University of Iceland, Reykjavik, Iceland. 3 Sleep Department, Landspitali - The National University Hospital of Iceland, Reykjavik, Iceland. 4 Reykjavik University, Reykjavik, Iceland. 5 Faculty of Medicine, Department of Biochemistry and Molecular Biology, Biomedical Center, University of Iceland, Reykjavik, Iceland. (Springer Heidelberg, 2018-12-01)
      The inflammatory markers chitinase-3-like protein 1 (CHI3L1) and chitotriosidase (CHIT1) have both been associated with cardiovascular complications. The aim of this preliminary observational study was to assess the roles and interaction of obstructive sleep apnea (OSA) severity and body mass index (BMI) with plasma CHI3L1 levels and CHIT1 activity in patients with moderate to severe OSA. The second aim was to assess the roles and interaction of positive airway pressure (PAP) treatment and BMI on the expression of the same proteins. The study included 97 OSA patients with an apnea-hypopnea index (AHI) ≥ 15 and full usage of PAP treatment after 4 months. Plasma CHI3L1 levels and CHIT1 activity were measured before and after treatment. Multiple linear regression analysis demonstrated an independent association of BMI on CHI3L1 levels (p < 0.05) but not on CHIT1 activity. The OSA severity markers (AHI and oxygen desaturation index) did not independently or in interaction with BMI levels associate with CHI3L1 levels or with CHIT1 activity (p > 0.05). A two-way repeated measures ANOVA revealed a significant interaction between PAP treatment effect (before vs. after) and BMI groups (< 35 kg/m Obesity independently associated with CHI3L1 levels. Association between OSA severity and CHI3L1 levels or CHIT1 activity (independent of or dependent on obesity level) could not be confirmed. However, decrease was observed in CHI3L1 levels after PAP treatment in severely obese OSA patients but not in those less obese.
    • Serum ferritin and obstructive sleep apnea-epidemiological study.

      Thorarinsdottir, Elin H; Arnardottir, Erna S; Benediktsdottir, Bryndis; Janson, Christer; Olafsson, Isleifur; Pack, Allan I; Gislason, Thorarinn; Keenan, Brendan T; 1 Faculty of Medicine, The National University of Iceland, Reykjavík, Iceland. 2 Sleep Department (E7), Landspitali-The National University Hospital of Iceland, 108, Reykjavík, Iceland. 3 Department of Medical Sciences: Respiratory, Allergy and Sleep Research, Uppsala University, Uppsala, Sweden. 4 Department of Clinical Biochemistry, Landspitali-The National University Hospital of Iceland, Reykjavík, Iceland. 5 Center for Sleep and Circadian Neurobiology and Division of Sleep Medicine/ Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA. 6 Faculty of Medicine, The National University of Iceland, Reykjavík, Iceland. thorarig@landspitali.is. 7 Sleep Department (E7), Landspitali-The National University Hospital of Iceland, 108, Reykjavík, Iceland. thorarig@landspitali.is. (Springer Heidelberg, 2018-01-01)
      Ferritin is an intracellular iron storage protein and a marker of inflammation. Studies have shown that subjects with obstructive sleep apnea (OSA) have higher levels of circulating pro-inflammatory cytokines, but little is known about the association between ferritin and OSA. The aims of the study were to evaluate serum ferritin (S-Ferritin) levels in OSA patients compared to levels in the general population and also examine the effect of obesity level and treatment with positive airway pressure (PAP) on S-Ferritin levels. The OSA subjects (n = 796) were part of the Icelandic Sleep Apnea Cohort. The control subjects (n = 637) were randomly chosen Icelanders who participated in an epidemiological study. Propensity score (PS) methodologies were employed to minimize selection bias and strengthen causal inferences when comparing non-randomized groups. S-Ferritin levels were measured and all participants answered the same detailed questionnaire about sleep and health. Only OSA patients underwent a sleep study and were re-invited for a 2-year follow-up. S-Ferritin levels were significantly higher in OSA males than controls (213.3 vs. 197.3 μg/L, p = 0.007). However, after adjusting for confounders and using our PS methodology, no significant difference was found. S-Ferritin levels were not correlated with severity of OSA, obesity level, or clinical symptoms. Also, no significant change in S-Ferritin levels was found with 2 years of PAP treatment. S-Ferritin levels are comparable in OSA patients and controls and do not change consistently with obesity level or PAP treatment in our sample.