{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,28]],"date-time":"2026-08-28T23:32:45Z","timestamp":1787959965870,"version":"build-2784847793"},"reference-count":45,"publisher":"MDPI AG","issue":"20","license":[{"start":{"date-parts":[[2021,10,13]],"date-time":"2021-10-13T00:00:00Z","timestamp":1634083200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJERPH"],"abstract":"<jats:p>Chronic fatigue syndrome (CFS) is a heterogenous disorder of multiple disabling symptoms with complex manifestations. Network analysis is a statistical and interrogative methodology to investigate the prevalence of symptoms (nodes) and their inter-dependent (inter-nodal) relationships. In the present study, we explored the co-occurrence of symptoms in a cohort of Polish CFS patients using network analysis. A total of 110 patients with CFS were examined (75 females). The mean age of the total sample was 37.93 (8.5) years old while the mean duration of symptoms in years was 4.4 (4). Post-exertional malaise (PEM) was present in 75.45% of patients, unrefreshing sleep was noted in 89.09% and impaired memory or concentration was observed in 87.27% of patients. The least prevalent symptom was tender cervical or axillary lymph nodes, noted in 34.55% of the total sample. Three of the most densely connected nodes were the total number of symptoms, sore throat and PEM. PEM was positively related with impairment in memory or concentration. Both PEM and impairment in memory or concentration presence are related to more severe fatigue measured by CFQ and FIS. PEM presence was positively related with the presence of multi-joint pain and negatively with tender lymph nodes and muscle pain. Sore throat was related with objective and subjective autonomic nervous system impairment. This study helps define symptom presentation of CFS with the pathophysiology of specific systems and links with multidisciplinary contemporary molecular pathology, including comparative MRI.<\/jats:p>","DOI":"10.3390\/ijerph182010736","type":"journal-article","created":{"date-parts":[[2021,10,13]],"date-time":"2021-10-13T21:36:15Z","timestamp":1634160975000},"page":"10736","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["Network Analysis of Symptoms Co-Occurrence in Chronic Fatigue Syndrome"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5186-5037","authenticated-orcid":false,"given":"S\u0142awomir","family":"Kujawski","sequence":"first","affiliation":[{"name":"Department of Exercise Physiology and Functional Anatomy, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, 85-094 Bydgoszcz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8503-3172","authenticated-orcid":false,"given":"Joanna","family":"S\u0142omko","sequence":"additional","affiliation":[{"name":"Department of Exercise Physiology and Functional Anatomy, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, 85-094 Bydgoszcz, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Julia","family":"Newton","sequence":"additional","affiliation":[{"name":"Population Health Sciences Institute, The Medical School, Newcastle University, Newcastle-upon-Tyne NE2 4HH, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Natalie","family":"Eaton-Fitch","sequence":"additional","affiliation":[{"name":"National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute of Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"},{"name":"Consortium Health International for Myalgic Encephalomyelitis, Menzies Health Institute Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Donald","family":"Staines","sequence":"additional","affiliation":[{"name":"National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute of Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"},{"name":"Consortium Health International for Myalgic Encephalomyelitis, Menzies Health Institute Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sonya","family":"Marshall-Gradisnik","sequence":"additional","affiliation":[{"name":"National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute of Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"},{"name":"Consortium Health International for Myalgic Encephalomyelitis, Menzies Health Institute Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8453-7785","authenticated-orcid":false,"given":"Pawe\u0142","family":"Zalewski","sequence":"additional","affiliation":[{"name":"Department of Exercise Physiology and Functional Anatomy, Ludwik Rydygier Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, 85-094 Bydgoszcz, Poland"},{"name":"National Centre for Neuroimmunology and Emerging Diseases, Menzies Health Institute of Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"},{"name":"Consortium Health International for Myalgic Encephalomyelitis, Menzies Health Institute Queensland, Griffith University, Gold Coast, Brisbane, QLD 4222, Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,10,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1111\/j.1365-2796.2011.02428.x","article-title":"Myalgic encephalomyelitis: International Consensus Criteria","volume":"270","author":"Carruthers","year":"2011","journal-title":"J. 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