Filling the gaps in the characterisation of the clinical management of COVID-19: Thirty-day hospital admission and fatality rates in a cohort of 118,150 cases diagnosed in outpatient settings in Spain

Objective Currently, there is a missing link in the natural history of COVID-19, from first (usually milder) symptoms to hospitalisation and/or death. To fill in this gap, we characterised COVID-19 patients at the time they were diagnosed in outpatient settings, and estimated 30-day hospital admission and fatality rates. Design Population-based cohort study. Setting Data were obtained from SIDIAP, a primary-care records database covering >6 million people (>80% of the population of Catalonia), linked to COVID-19 RT-PCR tests and hospital emergency, inpatient, and mortality registers. Participants We included all patients in the database who were over 15 years and diagnosed with COVID-19 in outpatient settings between 15 March and 24 April 2020 (10 April for outcome studies). Baseline characteristics included socio-demographics, comorbidity, and previous drug use at the time of diagnosis, and PCR testing and results. Outcome measures Study outcomes included 30-day hospitalisation for COVID-19 and all-cause fatality. Results We identified 118,150 and 95,467 COVID-19 patients for characterisation and outcome studies, respectively. Most were women (58.7%) and young-to-middle-aged (e.g., 21.1% were 45-54 years). Of the 44,575 who were tested with PCR, 32,723 (73.4%) tested positive. In the month after diagnosis, 14.8% [14.6-15.0] were hospitalised, with a greater proportion of men and older people, peaking at age 75-84. Thirty-day fatality was 3.5% [95% CI: 3.4% to 3.6%], higher in men, increasing with age, and highest in those residing in nursing homes (24.5% [23.4% to 25.6%]). Conclusions COVID-19 infections were widespread in the community, including all age-sex strata. However, severe forms of the disease clustered in older men and nursing-home residents. Although initially managed in outpatient settings, 15% of cases required hospitalisation and 4% died within a month of first symptoms. These data are instrumental for designing deconfinement strategies, and will inform healthcare planning and hospital bed allocation in current and future COVID-19 outbreaks.</p