Background: Investigation for the presence of asthma comorbidities is recommended by the Global Initiative for Asthma because their presence can complicate asthma management., Objective: To understand the prevalence and pattern of comorbidities and multimorbidity in adults with severe asthma and their association with asthma-related outcomes., Methods: This was a cross-sectional study using data from the International Severe Asthma Registry from 22 countries. A total of 30 comorbidities were identified and categorized a priori as any of the following: (1) potentially type 2-related comorbidities, (2) potentially oral corticosteroid (OCS)-related comorbidities, or (3) comorbidities mimicking or aggravating asthma. The association between comorbidities and asthma-related outcomes was investigated using multivariable models adjusted for country, age at enrollment, and sex (ie male or female)., Results: Of the 11,821 patients, 69%, 67%, and 55% had at least 1 potentially type 2-related, potentially OCS-related, or mimicking or aggravating comorbidities, respectively; 57% had 3 or more comorbidities, and 33% had comorbidities in all 3 categories. Patients with allergic rhinitis, nasal polyposis, and chronic rhinosinusitis experienced 1.12 (P = .003), 1.16 (P < .001), and 1.29 times (P < .001) more exacerbations per year, respectively, than those without. Patients with nasal polyposis and chronic rhinosinusitis were 40% and 46% more likely (P < .001), respectively, to have received long-term (LT) OCS. All assessed potential OCS-related comorbidities (except obesity) were associated with a greater likelihood of LTOCS use (odds ratios [ORs]: 1.23-2.77) and, except for dyslipidemia, with a greater likelihood of uncontrolled asthma (ORs: 1.29-1.68). All mimicking or aggravating comorbidities assessed were associated with more exacerbations (1.24-1.68 times more), all (except bronchiectasis) with increased likelihood of uncontrolled asthma (ORs: 1.57-1.81), and all (except chronic obstructive pulmonary disease) with increased likelihood of LTOCS use (ORs: 1.37-1.57). A greater number of comorbidities was associated with worse outcomes., Conclusion: In a global study, comorbidity or multimorbidity is reported in most adults with severe asthma and is associated with poorer asthma-related outcomes., Clinical Trial Registration: The International Severe Asthma Registry database has ethical approval from the Anonymous Data Ethics Protocols and Transparency (ADEPT) committee (ADEPT0218) and is registered with the European Union Electronic Register of Post-Authorization Studies (European Network Centres for Pharmacoepidemiology and Pharmacovigilance [ENCEPP]/DSPP/23720). The study was designed, implemented, and reported in compliance with the European Network Centres for Pharmacoepidemiology and Pharmacovigilance (ENCEPP) Code of Conduct (EMA 2014; EUPAS44024) and with all applicable local and international laws and regulations, and registered with ENCEPP (https://www.encepp.eu/encepp/viewResource.htm?id=48848). Governance was provided by ADEPT (registration number: ADEPT1121)., Competing Interests: Disclosures Dr Scelo and Dr Murray are consultants for the Observational and Pragmatic Research Institute (OPRI). Dr Torres-Duque has received fees as an advisory board participant and/or speaker from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Sanofi-Aventis; has taken part in clinical trials from AstraZeneca, Novartis, and Sanofi-Aventis; and has received unrestricted grants for investigator-initiated studies at Fundacion Neumologica Colombiana from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Grifols, and Novartis. Dr Maspero reports receiving speaker fees, grants, or fees for serving on advisory boards for AstraZeneca, Sanofi, GlaxoSmithKline, Novartis, Inmunotek, Menarini, and Noucor. Dr Tran, Dr Menzies-Gow, and Dr Martin are employees of AstraZeneca and may own stock or stock options in AstraZeneca. Dr Hew reports receiving grants and other advisory board fees (made to his institutional employer) from AstraZeneca, GlaxoSmithKline, Novartis, Sanofi, Teva, and Seqirus for unrelated projects. Dr Peters reports receiving personal fees and nonfinancial support from AstraZeneca and GlaxoSmithKline. Dr Gibson has received speaking fees and grants to his institution from AstraZeneca, GlaxoSmithKline, and Novartis. Dr Popov reports receiving relevant research support from Novartis and Chiesi Pharma. Dr Côté reports receiving speaking fees and consultant fees from Sanofi, Regeneron, AstraZeneca, GlaxoSmithKline, and ValeoPharma and reports receiving unrestricted grant support from GlaxoSmithKline; Dr Bergeron reports advisory board participation in Sanofi, AstraZeneca, Takeda, and ValeoPharma and honorarium for presentations for GlaxoSmithKline, AstraZeneca, Amgen, Grifols, Sanofi, Regeneron, and ValeoPharma. Dr Dorscheid is on faculty at the University of British Columbia and is supported by grants from the Canadian Institutes of Health Research, British Columbia Lung Association, and Michael Smith Foundation for Health Research. In addition, he has received speaking fees, travel grants, unrestricted project grants, and writing fees and is a paid consultant for Sanofi-Regeneron, Novartis Canada, AstraZeneca, GlaxoSmithKline, and ValeoPharma and is an active member of the Canadian Thoracic Society, American Thoracic Society, European Respiratory Society, and the Allergen Research Network. Dr FitzGerald previously reported receiving grants from AstraZeneca, GlaxoSmithKline, Sanofi-Regeneron, and Novartis paid directly to UBC and personal fees for lectures and attending advisory boards for AstraZeneca, GlaxoSmithKline, Sanofi-Regeneron, and Teva. Dr Chapman reports receiving grants from AstraZeneca, Boehringer Ingelheim, Bellus, CSL Behring, GlaxoSmithKline, Grifols, Inhibrx, Novartis, Regeneron, Sanofi, Takeda, and Vertex and consulting fees from AstraZeneca, CSL Behring, GlaxoSmithKline, Grifols, Inhibrx, Novartis, Sanofi, and Takeda; he has a leadership or fiduciary role in Alpha-1 Canada, the Canadian Thoracic Society, and Alpha-1 Foundation. Dr Boulet has received grants for participation in clinical studies from Amgen, AstraZeneca, GlaxoSmithKline, Merck, Novartis, Sanofi-Regeneron, and BioHaven; for consulting and advisory boards from AstraZeneca, Novartis, GlaxoSmithKline, Merck, and Sanofi-Regeneron; and lecture fees from AstraZeneca, Covis, Cipla, GlaxoSmithKline, Novartis, Merck, and Sanofi. Dr Bhutani has received speaker and consultant fees for AstraZeneca, GlaxoSmithKline, Sanofi, Covis, Boehringer Ingelheim, and Valeo. Dr Sadatsafavi has received honoraria from AstraZeneca, Boehringer Ingelheim, Teva, and GlaxoSmithKline for purposes unrelated to the content of this manuscript; and has received research funding from AstraZeneca and Boehringer Ingelheim directly into his research account from AstraZeneca for unrelated projects. Dr Jiménez-Maldonado has received fees as an advisory board participant and/or speaker from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Sanofi-Aventis and has participated in clinical trials for AstraZeneca, Novartis, and GlaxoSmithKline. Dr Duran-Silva has received fees as an advisory board participant and/or speaker from Boehringer Ingelheim, Novartis, and Sanofi-Aventis and has taken part in clinical trials from AstraZeneca, Novartis, and Sanofi-Aventis. Dr Solarte received fees from GlaxoSmithKline for participation on advisory boards. Dr Fernandez-Sanchez is a part-time employee of GlaxoSmithKline and does not hold shares in the company. Dr Bülow reports receiving speakers fees and consultancy fees from AstraZeneca and Novartis outside the submitted work and has also attended the advisory board for Novartis and AstraZeneca. Dr Bjerrum has received lecture fees from AstraZeneca, GlaxoSmithKline, and Novartis. Dr Ulrik reports receiving personal fees for talks and participation in advisory boards, among others, from AstraZeneca, GlaxoSmithKline, Teva, Boehringer Ingelheim, Orion Pharma, Sanofi-Genzyme, TFF Pharmaceuticals, Covis Pharma, Berlin-Chemie, Takeda, Chiesi, and Pfizer outside the submitted work. Dr Rasmussen declares receiving speaker fees from AstraZeneca, Boehringer Ingelheim, Teva, ALK, and Mundipharma outside the submitted work and attended advisory board for AstraZeneca, Sanofi, and Teva. Dr Altraja has received lecture fees from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, MSD, Norameda, Novartis, Orion, Sanofi, and Zentiva; sponsorships from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, MSD, Norameda, Novartis, and Sanofi; and has participated in advisory boards for AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, Sanofi, and Teva. Dr Bourdin has received industry-sponsored grants from AstraZeneca-MedImmune, Boehringer Ingelheim, Cephalon/Teva, GlaxoSmithKline, Novartis, and Sanofi-Regeneron and consultancies with AstraZeneca-MedImmune, Boehringer Ingelheim, GlaxoSmithKline, Novartis, Regeneron-Sanofi, Med-in-Cell, Actelion, Merck, Roche, and Chiesi. Dr Taille has received lecture or advisory board fees and grants to her institution from AstraZeneca, Sanofi, GlaxoSmithKline, Chiesi, and Novartis for unrelated projects. Dr Charriot reports receiving advisory board and lecture fees from AstraZeneca, GlaxoSmithKline, Sanofi; consulting fees for Chiesi; and serving as a trial coinvestigator for AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Sanofi. Dr Roche reports receiving grants and personal fees from Austral, Biosency, Boehringer Ingelheim, Novartis, and Pfizer and personal fees from MSD, GlaxoSmithKline, AstraZeneca, Chiesi, Sanofi, Menarini, and Zambon. Dr Papaioannou has received fees and honoraria from Menarini, GlaxoSmithKline, Novartis, Elpen, Boehringer Ingelheim, AstraZeneca, and Chiesi. Dr Kostikas received honoraria for presentations and consultancy fees from AstraZeneca, Boehringer Ingelheim, CSL Behring, Chiesi, ELPEN, GILEAD, GlaxoSmithKline, Menarini, Novartis, Sanofi, Specialty Therapeutics, and WebMD; and received funding and grants from AstraZeneca, Boehringer Ingelheim, Chiesi, Innovis, ELPEN, GlaxoSmithKline, Menarini, Novartis, and NuvoAir (paid to the University of Ioannina). Dr Papadopoulos has been a speaker and/or advisory board member for Abbott, AbbVie, ALK, Asit Biotech, AstraZeneca, Biomay, Boehringer Ingelheim, GlaxoSmithKline, HAL, Faes Farma, Medscape, Menarini, MSD, Novartis, Nutricia, OM Pharma, Regeneron, Sanofi, Takeda, and Viatris. Dr Salvi reports receiving research support and speaker fees from Cipla, Glenmark, and GlaxoSmithKline. Dr Mitchell has received speaker fees from GlaxoSmithKline, AstraZeneca, Teva, and Novartis and has received grants from AstraZeneca and Teva. Dr Costello has received honoraria for lectures from Aerogen, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Teva; is a member of advisory boards for GlaxoSmithKline and Novartis; has received grant support from GlaxoSmithKline and Aerogen; and has patents in the use of acoustics in the diagnosis of lung disease, assessment of adherence, and prediction of exacerbations. Dr Heffler declares receiving personal fees from Sanofi, Regeneron, GlaxoSmithKline, Novartis, AstraZeneca, Stallergenes, and Circassia. Dr Puggioni reports having received lectures or advisory board fees from Menarini, Mundipharma, Chiesi, Alk Abello, AstraZeneca, Boehringer Ingelheim, Guidotti, Malesci, GlaxoSmithKline, HAL Allergy, Novartis, Sanofi, Regeneron, Stallergenes Greer, Valeas, and Almirall. Dr Canonica has received research grants and lecture or advisory board fees from A. Menarini, Alk-Albello, Allergy Therapeutics, Anallergo, AstraZeneca, MedImmune, Boehringer Ingelheim, Chiesi Farmaceutici, Circassia, Danone, Faes, Genentech, Guidotti Malesci, GlaxoSmithKline, HAL Allergy, Merck, MSD, Mundipharma, Novartis, Orion, Sanofi-Aventis, Sanofi, Genzyme/Regeneron, Stallergenes, UCB Pharma, Uriach Pharma, Teva, Thermo Fisher, and Valeas. Dr Iwanaga received lecture fees from Kyorin, GlaxoSmithKline, Novartis, Boehringer Ingelheim, and AstraZeneca. Dr Mona Al-Ahmad has received advisory board and speaker fees from AstraZeneca, Sanofi, Novartis, and GlaxoSmithKline and received a grant from the Kuwait Foundation for the Advancement of Sciences (KFAS). Dr Linnemann reports receiving personal fees from ALK-Abelló, AstraZeneca national and global, Bayer, Chiesi, Grunenthal, Grin, GlaxoSmithKline national and global, Viatris, Menarini, MSD, Novartis, Pfizer, Sanofi, Siegfried, UCB, and Carnot and grants from AbbVie, Bayer, Lilly, Sanofi, AstraZeneca, Pfizer, Novartis, Circassia, UCB, and GlaxoSmithKline outside the submitted work. Dr Garcia Ramirez received fees as a speaker and advisory board participant from AstraZeneca, GlaxoSmithKline, Sanofi-Genzyme, Chiesi, and Novartis. Dr Kuna reports receiving personal fees from Adamed, AstraZeneca, Berlin-Chemie Menarini, FAES, Glenmark, Novartis, Polpharma, Boehringer Ingelheim, Teva, and Zentiva outside the submitted work. Dr Fonseca reports receiving grants from or has research agreements with AstraZeneca, Mundipharma, Sanofi-Regeneron, and Novartis and has received personal fees for lectures and attending advisory boards for AstraZeneca, GlaxoSmithKline, Mundipharma, Novartis, Sanofi-Regeneron, and Teva. Dr Lehebi has given lectures at meetings supported by AstraZeneca, Boehringer Ingelheim, Novartis, GlaxoSmithKline, and Sanofi and participated in advisory board fees from GlaxoSmithKline, AstraZeneca, Novartis, and Abbott. Dr Koh reports receiving grant support from AstraZeneca and honoraria for lectures and advisory board meetings paid to her hospital (Singapore General Hospital) from GlaxoSmithKline, AstraZeneca, Novartis, Sanofi, and Boehringer Ingelheim outside the submitted work. Dr Kook Rhee received consulting/lecture fees from MSD, AstraZeneca, GlaxoSmithKline, Novartis, Takeda, Mundipharma, Boehringer Ingelheim, Teva, Sanofi, and Bayer. Dr Cosio declares receiving grants from Chiesi and GlaxoSmithKline; personal fees for advisory board activities from Chiesi, GlaxoSmithKline, Novartis, Sanofi, Teva, and AstraZeneca; and payment for lectures/speaking engagements from Chiesi, Novartis, GlaxoSmithKline, Menarini, and AstraZeneca outside the submitted work. Dr de Llano reports receiving grants, personal fees and nonfinancial support from AstraZeneca, Teva, Faes, and Sanofi; personal fees and nonfinancial support from GlaxoSmithKline and Chiesi; personal fees from MSD, Techdow Pharma, GILEAD, and Leo Pharma; and grants and personal fees from GEBRO outside the submitted work. Dr Perng received sponsorship to attend or speak at international meetings, honoraria for lecturing or attending advisory boards, and research grants from the following companies: AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, Daiichi Sankyo, Shionogi, and Orient Pharma. Dr Tsai has received grants from Boehringer Ingelheim and has received honoraria for lectures from AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Novartis, and Orient EuroPharma. Dr Jackson has received speaker fees and consultancy fees from AstraZeneca, GlaxoSmithKline, Sanofi-Regeneron, and Boehringer Ingelheim and research funding from AstraZeneca. Dr Busby has received research grants from AstraZeneca and personnel fees from NuvoAir outside the submitted work. Dr Heaney has received grant funding, participated in advisory boards, and given lectures at meetings supported by Amgen, AstraZeneca, Boehringer Ingelheim, Chiesi, Circassia, Hoffmann la Roche, GlaxoSmithKline, Novartis, Theravance, Evelo Biosciences, Sanofi, and Teva; has received grants from MedImmune, Novartis UK, Roche/Genentech Inc, GlaxoSmithKline, Amgen, Genentech/Hoffman la Roche, AstraZeneca, Aerocrine, and Vitalograph; has received sponsorship for attending international scientific meetings from AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline, and Napp Pharmaceuticals; has taken part in asthma clinical trials sponsored by AstraZeneca, Boehringer Ingelheim, Hoffmann la Roche, and GlaxoSmithKline, for which his institution received remuneration; and is the Academic Lead for the Medical Research Council Stratified Medicine UK Consortium in Severe Asthma, which involves industrial partnerships with a number of pharmaceutical companies including Amgen, AstraZeneca, Boehringer Ingelheim, GlaxoSmithKline, Hoffmann la Roche, and Janssen. Dr Pfeffer has attended advisory boards for AstraZeneca, GlaxoSmithKline, and Sanofi; has given lectures at meetings supported by AstraZeneca and GlaxoSmithKline; has taken part in clinical trials sponsored by AstraZeneca, GlaxoSmithKline, Novartis, and Sanofi, for which his institution received remuneration; and has a current research grant funded by GlaxoSmithKline. Dr Goddard reports receiving lecture fees from Sanofi. Dr Wang has received honoraria from AstraZeneca, GlaxoSmithKline, and Genentech; and has been an investigator on studies sponsored by AstraZeneca, GlaxoSmithKline, Genentech, Sanofi, Novartis, and Teva, for which her institution has received funding. Dr Hoyte reports receiving honoraria from AstraZeneca and Genentech and has been an investigator on clinical trials sponsored by GlaxoSmithKline, Genentech, Teva, and Sanofi, for which her institution has received funding. Dr Wechsler reports receiving grants and/or personal fees from Novartis, Sanofi, Regeneron, Genentech, Sentien, resTORbio, Equillium, Genzyme, Cohero Health, Teva, Boehringer Ingelheim, AstraZeneca, Amgen, GlaxoSmithKline, Cytoreason, Cerecor, Sound biologic, Incyte, and Kinaset. Ms Carter is an employee of Optimum Patient Care (OPC) (OPC is a cofounder of the International Severe Asthma Registry and a cofounder of the APEX-COPD initiative). Ms Bulathsinhala is an employee of OPRI. Ms Eleangovan and Mr Ariti were employees of OPRI. Dr Lyu was an employee of OPC. Dr Price has advisory board membership with Amgen, AstraZeneca, Boehringer Ingelheim, Chiesi, Circassia, Mylan, Mundipharma, Novartis, Regeneron Pharmaceuticals, Sanofi-Genzyme, Teva Pharmaceuticals, Thermofisher; consultancy agreements with Amgen, AstraZeneca, Boehringer Ingelheim, Chiesi, GlaxoSmithKline, Mylan, Mundipharma, Novartis, Pfizer, Teva Pharmaceuticals, Theravance; received grants and unrestricted funding for investigator-initiated studies (conducted through OPRI Pte Ltd) from AstraZeneca, Boehringer Ingelheim, Chiesi, Circassia, Mylan, Mundipharma, Novartis, Pfizer, Regeneron Pharmaceuticals, Respiratory Effectiveness Group, Sanofi-Genzyme, Teva Pharmaceuticals, Theravance, and the UK National Health Service; received payment for lectures/speaking engagements from AstraZeneca, Boehringer Ingelheim, Chiesi, Cipla, GlaxoSmithKline, Kyorin, Mylan, Mundipharma, Novartis, Regeneron Pharmaceuticals, Sanofi-Genzyme, Teva Pharmaceuticals; payment for the development of educational materials from Mundipharma, Novartis; payment for travel/accommodation/meeting expenses from AstraZeneca, Boehringer Ingelheim, Mundipharma, Mylan, Novartis, Thermofisher; funding for patient enrollment or completion of research from Novartis; has stock/stock options from AKL Research and Development Ltd, which produces phytopharmaceuticals; owns 74% of the social enterprise OPC Ltd (Australia and UK) and 74% of OPRI Pte Ltd (Singapore); has 5% shareholding in Timestamp, which develops adherence monitoring technology; is a peer reviewer for grant committees of the Efficacy and Mechanism Evaluation program and Health Technology Assessment; and was an expert witness for GlaxoSmithKline. Dr Porsbjerg has attended advisory boards for AstraZeneca, Novartis, Teva, and Sanofi-Genzyme; has given lectures at meetings supported by AstraZeneca, Novartis, Teva, Sanofi-Genzyme, and GlaxoSmithKline; has taken part in clinical trials sponsored by AstraZeneca, Novartis, MSD, Sanofi-Genzyme, GlaxoSmithKline, and Novartis; and has received educational and research grants from AstraZeneca, Novartis, Teva, GlaxoSmithKline, ALK, and Sanofi-Genzyme. The remaining authors have no conflicts of interest to report., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)