Associations between area-level socioeconomic disadvantage and COVID-19 disease consequences in Sydney, Australia: A retrospective cohort analysis

BackgroundSocioeconomic disparities have shaped COVID-19 outcomes worldwide. Focusing on disease consequences once infected (severity among cases), we examined whether area-level socioeconomic disadvantage was associated with hospitalisation and death among COVID-19 cases in Greater Sydney, Australia. MethodsWe conducted a retrospective cohort study of confirmed and probable COVID-19 cases recorded in the New South Wales Notifiable Conditions Information Management System from 2 March 2020 to 21 February 2022. Area-level disadvantage was measured using the Index of Relative Socio-Economic Disadvantage (IRSD). We modelled the odds of (a) hospitalisation and (b) death conditional on infection using logistic regression, adjusting for age and gender. ResultsAmong 782,883 included cases, 3.5% were hospitalised and 0.2% died due to COVID-19. Greater area-level disadvantage (lower IRSD) was associated with higher odds of hospitalisation (adjusted odds ratio [AOR] 0.996 per IRSD point; 95% CI 0.996-0.996) and death (AOR 0.997; 95% CI 0.996-0.997), holding age and gender constant. For illustration, the difference between two Sydney postal areas with markedly different IRSD scores corresponds to several-fold differences in the odds of hospitalisation and death among cases. ConclusionsArea-level socioeconomic disadvantage was associated with higher risks of hospitalisation and death among COVID-19 cases in Greater Sydney - a setting with public hospital care - indicating inequities in disease consequences once infected. Given the absence of individual-level comorbidity and vaccination data, the most plausible explanation is disparities in comorbidity and risk-factor burden, although contributions from differences in access to and quality of care cannot be ruled out. Public health responses should prioritise chronic-disease prevention and management in disadvantaged communities to mitigate inequitable outcomes in future pandemics.