nutrients Article Osteosarcopenia, an Asymmetrical Overlap of Two Connected Syndromes: Data from the OsteoSys Study Maryam Pourhassan 1, * , Bjoern Buehring 2 , Ulrik Stervbo 3 , Sven Rahmann 4 , Felix Mölder 5,6 , Sebastian Rütten 7 , Ulrike Trampisch 1 , Nina Babel 3,8 , Timm Henning Westhoff 3 and Rainer Wirth 1   Citation: Pourhassan, M.; Buehring, B.; Stervbo, U.; Rahmann, S.; Mölder, F.; Rütten, S.; Trampisch, U.; Babel, N.; Westhoff, T.H.; Wirth, R. Osteosarcopenia, an Asymmetrical Overlap of Two Connected Syndromes: Data from the OsteoSys Study. Nutrients 2021, 13, 3786. https://doi.org/10.3390/nu13113786 Received: 20 September 2021 Accepted: 23 October 2021 Published: 26 October 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Geriatric Medicine, Marien Hospital Herne, Ruhr-University Bochum, Hölkeskampring 40D, 44625 Herne, Germany; ulrike.trampisch@elisabethgruppe.de (U.T.); Rainer.Wirth@elisabethgruppe.de (R.W.) 2 Rheumazentrum Ruhrgebiet, Ruhr-University Bochum, 44649 Herne, Germany; Bjoern.Buehring@elisabethgruppe.de 3 Center for Translational Medicine and Immune Diagnostics Laboratory, Medical Department I, Marien Hospital Herne, Ruhr-University Bochum, 44625 Herne, Germany; ulrik.stervbo@elisabethgruppe.de (U.S.); nina.babel@elisabethgruppe.de (N.B.); timm.westhoff@elisabethgruppe.de (T.H.W.) 4 Algorithmic Bioinformatics, Center for Bioinformatics, Saarland University, 66041 Saarbrücken, Germany; Sven.Rahmann@uni-due.de 5 Algorithms for Reproducible Bioinformatics, Genome Informatics, Institute of Human Genetics, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany; felix.moelder@uni-due.de 6 Institute of Pathology, University Hospital Essen, University of Duisburg-Essen, 45147 Essen, Germany 7 Center for Orthopedics and Trauma Surgery, St. Anna Hospital, St. Elisabeth Gruppe, 44649 Herne, Germany; sebastian.ruetten@elisabethgruppe.de 8 Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin-Brandenburg Center for Regenerative Therapies, 10117 Berlin, Germany * Correspondence: maryam.pourhassan@ruhr-uni-bochum.de; Tel.: +49-2323-499-2416; Fax: +49-2323-499-2417 Abstract: Osteoporosis and sarcopenia are two chronic conditions, which widely affect older people and share common risk factors. We investigated the prevalence of low bone mineral density (BMD) and sarcopenia, including the overlap of both conditions (osteosarcopenia) in 572 older hospitalized patients (mean age 75.1 ± 10.8 years, 78% women) with known or suspected osteoporosis in this prospective observational multicenter study. Sarcopenia was assessed according to the revised defini- tion of the European Working Group on Sarcopenia in Older People (EWGSOP2). Low BMD was defined according to the World Health Organization (WHO) recommendations as a T-score < -1.0. Osteosarcopenia was diagnosed when both low BMD and sarcopenia were present. Low BMD was prevalent in 76% and the prevalence of sarcopenia was 9%, with 90% of the sarcopenic patients showing the overlap of osteosarcopenia (8% of the entire population). Conversely, only few patients with low BMD demonstrated sarcopenia (11%). Osteosarcopenic patients were older and frailer and had lower BMI, fat, and muscle mass, handgrip strength, and T-score compared to nonosteosar- copenic patients. We conclude that osteosarcopenia is extremely common in sarcopenic subjects. Considering the increased risk of falls in patients with sarcopenia, they should always be evaluated for osteoporosis. Keywords: osteopenia; osteoporosis; sarcopenia; osteosarcopenia; bone mineral density; muscle mass 1. Introduction Osteoporosis and sarcopenia are two chronic conditions, which widely affect older people and share a common pathophysiology [1]. Both entities are associated with an increased risk of fractures and other complications and create a significant economic and social burden for the health care system [2–4]. Osteoporosis is a systemic bone disease characterized by decreased bone mineral density (BMD) and degraded microarchitecture, resulting in the development of fragility fractures [5]. By contrast, sarcopenia is a muscle Nutrients 2021, 13, 3786. https://doi.org/10.3390/nu13113786 https://www.mdpi.com/journal/nutrients