Patterns of outpatient antibiotic prescribing in older adults by social determinants of healthcare access: a population-based retrospective cohort study

Objectives — Strategies to improve antibiotic use may exacerbate health inequities if they do not consider existing barriers to healthcare access. We examined associations between social determinants of healthcare access (SDOH) and antibiotic prescribing and variations in these associations pre- and post-COVID-19 emergence.

Methods — We conducted a retrospective cohort study of community-dwelling adults ≥66 years of age in Ontario, Canada between March 2018 to March 2020 (pre-pandemic period) and March 2020 to March 2022 (pandemic period). Multivariable Fine-Gray subdistribution hazard models were used to examine associations between three SDOH variables (neighbourhood-level income and proportion racialized, and individual-level recent immigration) and incident antibiotic prescriptions, accounting for mortality as a competing risk. We assessed for potential effect modification by the pandemic period.

Results — The pre-pandemic (n=2,567,382) and pandemic (n=2,744,337) cohorts were similar in average age (75 years). Antibiotic prescribing was slightly higher among residents in the highest income neighbourhoods in pre-pandemic (subdistribution hazard ratio [sHR] 1.03 [95% confidence interval 1.02-1.04], compared with lowest income) and pandemic (sHR 1.02 [1.01-1.03]) periods. Prescribing was higher among recent immigrants (vs. long-term residents) in both periods, with a more pronounced difference observed during the pandemic (sHR 1.21 [1.18-1.25]) than pre-pandemic (sHR 1.12 [1.09-1.16]) period. Prescribing was lower among residents living in the most diverse neighbourhoods (vs. least diverse) in both periods, with a more pronounced difference during the pandemic (sHR 0.81 [0.80-0.82]) than pre-pandemic (sHR 0.92 [0.91-0.93]) period.

Conclusions — SDOH variables are associated with antibiotic prescribing patterns over time among older outpatients, and the COVID-19 pandemic further modified some of these associations.