Participants
cardiovascular comorbidity, anaemia, shortness of breath
RESPIRATORY TRACT INFECTION, ANAEMIA
Patients were aged ≥40 years with cardiovascular comorbidity who presented to the GP with moderate-to-severe COVID-19 symptoms. Moderate-to-severe symptoms were defined as at least 3 days with a body temperature ≥37.5°C and either a) new onset of symptoms of respiratory tract infection; b) a feeling of shortness of breath; and/or c) sudden exhaustion. They were patients for whom it was considered necessary to closely follow-up, according to the GP. The following patients were excluded: those requiring hospital admission; those with known severe anaemia (pulse oximetry can be inaccurate and SpOGPs from 14 participating general practices in the vicinity of Utrecht informed potentially eligible participants about the study verbally and via a patient information letter. Those who were interested, and tested positive for COVID-19, were asked for consent to share their contact details with the University Medical Center (UMC) Utrecht research team for eligibility screening. Eligible patients who expressed interest in trial participation were visited at home under safe circumstances with COVID-19 protection to obtain full-written informed consent. Next, the study physician accessed a trial randomisation website for concealed study treatment assignment via a computer-generated sequence list developed by an independent data manager, that is, home monitoring by pulse oximetry or usual care. The study physician informed the GP about the randomisation result.