Prognostic Factors for Predicting Post-COVID-19 Condition in Patients With COVID-19 in an Outpatient Setting

Background: Although data on post-coronavirus disease 2019 (COVID-19) conditions are extensive, the prognostic factors affecting symptom duration in non-hospitalized patients with COVID-19 are currently not well known. We aimed to investigate the various prognostic factors affecting symptom duration among outpatients with COVID-19. Methods: Data were analyzed from 257 patients who were diagnosed with mild COVID-19 and visited the ‘post-COVID-19 outpatient clinic’ between April and December 2022 after a mandatory isolation period. The symptom duration was measured from diagnosis to symptom resolution. Laboratory and pulmonary function test results from their first visit were collected. Results: The mean age of patients was 55.7 years, and the median symptom duration was 57 days. The development of post-COVID-19 conditions (> 12 weeks) were significantly correlated with not using antiviral drugs, leukocytosis (white blood cell > 10,000/μL), lower 25(OH)D3 levels, forced vital capacity (FVC) < 90% predicted, and presence of dyspnea and anxiety/depression. Additionally, in multivariable Cox regression analysis, not using antiviral drugs, lower 25(OH)D3 levels, and having dyspnea were poor prognostic factors for longer symptom duration. Particularly, vitamin D deficiency (< 20 ng/mL) and not using antivirals during the acute phase were independent poor prognostic factors for both post-COVID-19 condition and longer symptom duration. Conclusion: The non-use of antivirals, lower 25(OH)D3 levels, leukocytosis, FVC < 90% predicted, and the presence of dyspnea and anxiety/depression symptoms could be useful prognostic factors for predicting post-COVID-19 condition in outpatients with COVID-19. We suggest that the use of antiviral agents during the acute phase and vitamin D supplements might help reduce COVID-19 symptom duration.