Epidemiological characteristics and outcomes of COVID-19 cases: Mortality inequalities by socioeconomic status, Barcelona, Spain, 24 February to 4 May 2020

Background: Population-based studies characterising outcomes of COVID-19 in European settings are limited, and effects of socio-economic status (SES) on outcomes have not been widely investigated. Aim: We describe the epidemiological characteristics of COVID-19 cases, highlighting incidence and mortality rate differences across SES during the first wave in Barcelona, Catalonia, Spain. Methods: This population-based study reports individual-level data of laboratory-confirmed COVID-19 cases diagnosed from 24 February to 4 May 2020, notified to the Public Health Agency of Barcelona and followed until 15 June 2020. We analysed end-of-study vital status and the effects of chronic conditions on mortality using logistic regression. Geocoded addresses were linked to basic health area SES data, estimated using the composed socio-economic index. We estimated age-standardised incidence, hospitalisation, and mortality rates by SES. Results: Of 15,554 COVID-19-confirmed cases, the majority were women (n =9,028; 58%), median age was 63 years (interquartile range: 46-83), 8,046 (54%) required hospitalisation, and 2,287 (15%) cases died. Prevalence of chronic conditions varied across SES, and multiple chronic conditions increased risk of death (≥3, adjusted odds ratio: 2.3). Age-standardised rates (incidence, hospitalisation, mortality) were highest in the most deprived SES quartile (incidence: 1,011 (95% confidence interval (CI): 975-1,047); hospitalisation: 619 (95% CI: 591-648); mortality: 150 (95% CI: 136-165)) and lowest in the most affluent (incidence: 784 (95% CI: 759-809); hospitalisation: 400 (95% CI: 382-418); mortality: 121 (95% CI: 112-131)). Conclusions: COVID-19 outcomes varied markedly across SES, underscoring the need to implement effective preventive strategies for vulnerable populations.