Socioeconomic Position and the Cascade From SARS-CoV-2 Testing to COVID-19 Mortality: Population-Based Analysis of Swiss Surveillance Data

Abstract

Background: The inverse care law states that disadvantaged populations need more health care than advantaged populations but receive less. Gaps in COVID-19 related health care and infection control are not well understood at present. We examined inequalities in health in the care cascade from testing for SARS-CoV-2 to COVID-19-related hospitalisation, ICU admission and death in Switzerland, a wealthy country strongly affected by the pandemic.

Methods: We analysed surveillance data reported to the Federal Office of Public Health from March 1, 2020 to April 16, 2021 and 2018 population data. We geocoded residential addresses of notifications to determine the Swiss neighbourhood index of socioeconomic position (Swiss-SEP). The index describes 1.27 million small neighbourhoods of about 50 households, based on rent per square meter, education and occupation of household heads, and crowding. We used negative binomial regression models to calculate incidence rate ratios (IRR) with 95% credible intervals [CrI] of the association between ten groups of the Swiss-SEP index defined by deciles (1=lowest, 10=highest) and outcomes. Models were adjusted for sex, age, canton and wave of the epidemic (before or after June 8, 2020). We used three different denominators: the general population, the number of tests, and the number of positive tests.

Findings: Analyses were based on 4,129,636 tests, 609,782 positive tests, 26,143 hospitalisations, 2,432 ICU admissions, 9,383 deaths, and 8,221,406 residents. Comparing the highest with the lowest Swiss-SEP group, and using the general population as the denominator, more tests were performed among people living in neighbourhoods of highest socioeconomic position (adjusted IRR 1.18; 95%CrI 1.02-1.36). Among tested people, test positivity was lower (adjusted IRR 0.75; 0.69-0.81) in neighbourhoods of highest socioeconomic position. Among people testing positive, the corresponding IRRs for hospitalisation, ICU admission and death were 0.68 (0.62-0.74), 0.54 (0.43-0.70) and 0.86 (0.76-0.99). The associations between neighbourhood socioeconomic position and outcomes were stronger in younger age groups, and there was heterogeneity between areas.

Interpretation: The inverse care law and socioeconomic inequalities are evident in Switzerland throughout the care cascade. People living in neighbourhoods of low socioeconomic position were less likely to be tested but more likely to test positive, be hospitalised, or die. It is essential to continue to monitor testing for SARS-CoV-2, access and uptake of COVID-19 vaccination and outcomes of COVID-19. Governments and health care systems should address this pandemic of inequality by taking measures to reduce health inequalities in response to the SARS-CoV-2 pandemic.

Funding Information: Federal Office of Public Health, Swiss National Science Foundation (grant 189498), European Union Horizon 2020 (grant 101003688).

Declaration of Interests: The authors declare no competing interests.

Ethics Approval Statement: We conducted this research using surveillance data according to the Swiss law on communicable diseases (EpG, SR 818.101). No ethical approval was required.

Keywords: SARS-CoV-2, COVID-19, Switzerland, socioeconomic position, social inequalities in health