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

Background Socioeconomic 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. Methods We 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. Results Among 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. Conclusions Area?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.