pISSN 2005-9159
eISSN 2093-0569

Clinical Research Article

Korean J Pain 2022; 35(4): 458-467

Published online October 1, 2022 https://doi.org/10.3344/kjp.2022.35.4.458

Copyright © The Korean Pain Society.

Associations of unspecified pain, idiopathic pain and COVID-19 in South Korea: a nationwide cohort study

Namwoo Kim1,2 , Jeewuan Kim3 , Bo Ram Yang4 , Bong-Jin Hahm1,5

1Department of Neuropsychiatry, Seoul National University Hospital, Seoul, Korea
2Department of Clinical Medical Sciences, Seoul National University College of Medicine, Seoul, Korea
3Department of Statistics and Data Science, Yonsei University, Seoul, Korea
4College of Pharmacy, Chungnam National University, Daejeon, Korea
5Department of Psychiatry and Behavioral Sciences, Seoul National University College of Medicine, Seoul, Korea

Correspondence to:Bong-Jin Hahm
Department of Neuropsychiatry, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea
Tel: +82-2-2072-2458
Fax: +82-2-743-2838
E-mail: hahmbj@gmail.com

*These authors contributed equally to this work.

Handling Editor: Francis S. Nahm

Author contributions: Namwoo Kim: Study conception; Jeewuan Kim: Formal analysis; Bo Ram Yang: Writing/manuscript preparation; Bong-Jin Hahm: Supervision.

Received: May 4, 2022; Revised: June 18, 2022; Accepted: June 30, 2022

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background: Few studies have investigated unspecified or idiopathic pain associated with COIVD-19. This study aimed to provide the incidence rates of unspecified pain and idiopathic pain in patients with COVID-19 for 90 days after COVID-19 diagnosis.
Methods: A propensity score matched cohort was used, including all patients with COVID-19 in South Korea, and analyzed their electronic medical records. The control group consisted of those who had not had tests for COVID-19 at all. Unspecified pain diagnoses consisted of diagnoses related to pain included in the ICD-10 Chapter XVIII. Idiopathic pain disorders included fibromyalgia, temporomandibular joint disorders, headaches, chronic prostatitis, complex regional pain syndrome, atypical facial pain, irritable bowel syndrome, and interstitial cystitis.
Results: After matching, the number of participants in each group was 7,911. For most unspecified pain, the incidences were higher in the COVID-19 group (11.7%; 95% confidence interval [CI], 11.0–12.5) than in the control group (6.5%; 95% CI, 6.0–7.1). For idiopathic pain, only the headaches had a significantly higher incidence in the COVID-19 group (6.6%; 95% CI, 6.1–7.2) than in the control group (3.7%; 95% CI, 3.3–4.1). However, using a different control group that included only patients who visited a hospital at least once for any reasons, the incidences of most unspecified and idiopathic pain were higher in the control group than in the COVID-19 group.
Conclusions: Patients with COVID-19 might be at a higher risk of experiencing unspecified pain in the acute phase or after recovery compared with individuals who had not had tests for COVID-19.

Keywords: COVID-19, Electronic Health Records, Epidemiologic Studies, Headache, Insurance Claim Review, Pain, Post-Acute COVID-19 Syndrome, Post-Infectious Disorders, Propensity Score.