Epidemiology of post-COVID conditions beyond 1 year: a cross-sectional study.

OBJECTIVE: The aim of this study was to investigate the epidemiology of post-COVID conditions beyond 12 months and identify factors associated with the persistence of each condition. STUDY DESIGN: This was a cross-sectional questionnaire-based survey. METHODS: We conducted the survey among patients who had recovered from COVID-19 and visited our institute between February 2020 and November 2021. Demographic and clinical data and data regarding the presence and duration of post-COVID conditions were obtained. We identified factors associated with the persistence of post-COVID conditions using multivariable linear regression analyses. RESULTS: Of 1148 surveyed patients, 502 completed the survey (response rate, 43.7%). Of these, 393 patients (86.4%) had mild disease in the acute phase. The proportion of participants with at least one symptom at 6, 12, 18, and 24 months after symptom onset or COVID-19 diagnosis was 32.3% (124/384), 30.5% (71/233), 25.8% (24/93), and 33.3% (2/6), respectively. The observed associations were as follows: fatigue persistence with moderate or severe COVID-19 (ß = 0.53, 95% confidence interval [CI] = 0.06-0.99); shortness of breath with moderate or severe COVID-19 (ß = 1.39, 95% CI = 0.91-1.87); cough with moderate or severe COVID-19 (ß = 0.84, 95% CI = 0.40-1.29); dysosmia with being female (ß = -0.57, 95% CI = -0.97 to -0.18) and absence of underlying medical conditions (ß = -0.43, 95% CI = -0.82 to -0.05); hair loss with being female (ß = -0.61, 95% CI = -1.00 to -0.22), absence of underlying medical conditions (ß = -0.42, 95% CI = -0.80 to 0.04), and moderate or severe COVID-19 (ß = 0.97, 95% CI = 0.41-1.54); depressed mood with younger age (ß = -0.02, 95% CI = -0.04 to -0.004); and loss of concentration with being female (ß = -0.51, 95% CI = -0.94 to -0.09). CONCLUSIONS: More than one-fourth of patients after recovery from COVID-19, most of whom had had mild disease in the acute phase, had at least one symptom at 6, 12, 18, and 24 months after onset of COVID-19, indicating that not a few patients with COVID-19 suffer from long-term residual symptoms, even in mild cases.