Impact of chronic pain on numerous long COVID-like symptoms: A large-scale internet-based epidemiological study in Japan

BackgroundIndividuals with chronic pain (CP) not only endure the direct burden of the pain but also experience various symptoms, including sleep disturbances and fatigue, which deteriorate their quality of life. Notably, these symptoms closely resemble those observed in long COVID, a prolonged health complication that can arise after coronavirus disease 2019 (COVID-19) infection. However, the similarities between them have not yet been explored. Therefore, this study aimed to investigate the relationship between CP and long COVID using Japanese epidemiological data. MethodsUtilizing the Japan COVID-19 and Society Internet Survey in 2022, an Internet-based survey involving 32,000 participants, we analysed data on the presence of CP, history of COVID-19 infection, and presence of 17 long COVID-like symptoms, including gastrointestinal upset, back pain, limb/joint pain, headache, chest pain, shortness of breath, dizziness, sleep disorder, hearing disorder, taste disorder, smell disorder, memory impairment, poor concentration, hair loss, decreased libido, fatigue, and cough. ResultsIndividuals with history of COVID-19 experienced a significantly greater number of long COVID-like symptoms (median: 5) compared to those with neither COVID-19 nor CP (median: 4, p < 0.001). However, individuals with CP alone and those with both COVID-19 and CP exhibited an even greater number of symptoms (median: 8 and 9, respectively). Additionally, individuals with CP exhibited greater prevalence odds for 15 of the 17 symptoms than those without CP or COVID-19 (p < 0.001). ConclusionsAltogether, our study suggests that the long COVID-like symptoms are not specifically related to COVID-19, but CP is an independent risk factor for these symptoms.