The clinical course of COVID-19 in the outpatient setting: a prospective cohort study

Background: Outpatient COVID-19 has been insufficiently characterized. Objective: To determine the progression of disease and subsequent determinants of hospitalization. Design: A prospective outpatient cohort. Setting: Outpatients were recruited by phone between April 21 to June 23, 2020 after receiving outpatient or emergency department testing within a large health network in Maryland, USA. Participants: Outpatient adults with positive RT-PCR results for SARS-CoV-2. Measurements: Symptoms, portable pulse oximeter oxygen saturation (SaO2), heart rate, and temperature were collected by participants on days 0, 3, 7, 14, 21, and 28 after enrollment. Baseline demographics, comorbid conditions were evaluated for risk of subsequent hospitalization using negative binomial, logistic, and random effects logistic regression. Results: Among 118 SARS-CoV-2 infected outpatients, the median age was 56.0 years (IQR, 50.0 to 63.0) and 50 (42.4%) were male. Among those reporting active symptoms, the most common symptoms during the first week since symptom onset included weakness/fatigue (67.3%), cough (58.0%), headache (43.8%), and sore throat (34.8%). Participants returned to their usual health a median of 20 days (IQR, 13 to 38) from the symptom onset, and only 65.5% of respondents were at their usual health during the fourth week of illness. Over 28 days, 10.9% presented to the emergency department and 7.6% required hospitalization. Individuals at the same duration of illness had a 6.1 times increased adjusted odds of subsequent hospitalization per every percent decrease in home SaO2 (95% confidence interval [CI]: 1.41 to 31.23, p=0.02). Limitations: Severity and duration of illness may differ in a younger population. Conclusion: Symptoms often persisted but uncommonly progressed to hospitalization. Home SaO2 might be an important adjunctive tool to identify progression of COVID-19.