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

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. This was a cross-sectional questionnaire-based survey. 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. 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 (β = 0.53, 95% confidence interval [CI] = 0.06–0.99); shortness of breath with moderate or severe COVID-19 (β = 1.39, 95% CI = 0.91–1.87); cough with moderate or severe COVID-19 (β = 0.84, 95% CI = 0.40–1.29); dysosmia with being female (β = −0.57, 95% CI = −0.97 to −0.18) and absence of underlying medical conditions (β = −0.43, 95% CI = −0.82 to −0.05); hair loss with being female (β = −0.61, 95% CI = −1.00 to −0.22), absence of underlying medical conditions (β = −0.42, 95% CI = −0.80 to 0.04), and moderate or severe COVID-19 (β = 0.97, 95% CI = 0.41–1.54); depressed mood with younger age (β = −0.02, 95% CI = −0.04 to −0.004); and loss of concentration with being female (β = −0.51, 95% CI = −0.94 to −0.09). 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.