Cluster analysis of long COVID in Japan and association of its trajectory of symptoms and quality of life

Background Multiple prolonged symptoms observed in patients who recovered from COVID-19 are defined as long COVID. Although diverse phenotypic combinations are possible, they remain unclear. This study aimed to perform a cluster analysis of long COVID in Japan and clarify the association between its characteristics and background factors and quality of life (QOL).Methods This multicentre prospective cohort study collected various symptoms and QOL after COVID-19 from January 2020 to February 2021. This study included 935 patients aged >= 18 years with COVID-19 at 26 participating medical facilities. Hierarchical cluster analysis was performed using 24 long COVID symptom at 3 months after diagnosis.Results Participants were divided into the following five clusters: numerous symptoms across multiple organs (cluster 1, n=54); no or minor symptoms (cluster 2, n=546); taste and olfactory disorders (cluster 3, n=76); fatigue, psychoneurotic symptoms and dyspnoea (low prevalence of cough and sputum) (cluster 4, n=207) and fatigue and dyspnoea (high prevalence of cough and sputum) (cluster 5, n=52). Cluster 1 included elderly patients with severe symptoms, while cluster 3 included young female with mild symptoms. No significant differences were observed in the comorbidities. Cluster 1 showed the most impaired QOL, followed by clusters 4 and 5; these changes as well as the composition of symptoms were observed over 1 year.Conclusions We identified patients with long COVID with diverse characteristics into five clusters. Future analysis of these different pathologies could result in individualised treatment of long COVID.Trial registration number The study protocol is registered at UMIN clinical trials registry (UMIN000042299).