Association between socio-economic status and outcomes among critically ill Covid-19 adult patients in France.

Introduction: Socio-economic inequalities have been identified as a potential risk factor for adverse outcomes in patients with Covid-19. In the specific setting of critical care, data are currently more controversial. The aim of our study is to assess the impact of social inequalities on the outcome of patients admitted to intensive care unit (ICU) for Covid-19 through a national French observational study.

Methods: Based on the French administrative health care database, we identified all adults living in metropolitan France admitted in ICU for COVID-19 between March 1, 2020 and December 31, 2021. Two covariates were used to measure social vulnerability: an ecological deprivation index, the French deprivation index (Fdep), categorized in quintile (Q5 represented the most deprivated localization), and being a beneficiary of a complementary health coverage for the most deprived (CSS/AME beneficiary status). Primary outcome was in-hospital death. Secondary outcome was need for mechanical ventilation and post-acute care transfer in rehabilitation unit. Fine-Gray survival analysis or logistic regression were used according the competitive risk context. Three sensitivity analyses were performed: (1) restriction to patients admitted after January 1, 2021, adjusting for vaccination status; (2) multilevel logistic regression with a hospital-level random intercept; and (3) sex-stratified analyses.

Results: There were 120 191 patients admitted to ICU with Covid-19 across metropolitan France. Among them, 29 580 (24.6%) patients lived in the most disadvantage areas and 12 462 (10.4%) were CSS/AME beneficiaries. In multivariate analysis, Fdep and CSS/AME beneficiary status were both associated with higher likelihood of in-hospital death (aSHR = 1,21 ; 95%CI = 1,16 - 1,27 for Fdep-Q5 and aSHR = 1,06 ; 95%CI = 1,01-1,11 for being beneficiary of CSS/AME) and need for invasive mechanical ventilation (aSHR = 1,16 ; 95%CI = 1,12 - 1,20 for Fdep-Q5 and aSHR = 1,06 ; 95%CI = 1,02 - 1,09 for being beneficiary of CSS/AME). Among survivors, a post-acute care transfer was negatively associated Fdep-Q5 in patients above 60 years (OR = 0.88; 95%CI = 0.81-0.94), in CSS/AME beneficiaries under 60 years (OR = 0.87; 95%CI = 0.80-0.98) as well as above 60 years (aSHR = 0.81; 95%CI = 0.74-0.88). Results were consistent across all sensitivity analyses.

Conclusion: Social vulnerability was associated with higher hospital mortality, higher use of invasive mechanical ventilation and lower post-acute care transfer in rehabilitation unit in patients admitted to the ICU for COVID-19.