BACKGROUND: Australians living in regional and remote areas face health inequalities. Previous research has produced conflicting results around intensive care unit (ICU) outcomes for regional Australians.
OBJECTIVES: The aim of this study was to investigate the association between remoteness of residence on hospital mortality following an index ICU admission from 2010 to 2020.
METHODS: Semiecological retrospective cohort study of admissions to Australian ICUs. Residential postcode was used to stratify patients into five remoteness categories (major city, inner regional, outer regional, remote, or very remote). Individual admission characteristics and outcomes were compared across these strata and over time. The primary outcome was hospital mortality.
RESULTS: After exclusions, 1 422 165 patient episodes from 185 ICUs were analysed. Overall age-adjusted admission rates were lowest in major cities and highest in pooled remote areas (4.6 compared with 5.8 per 1000 person-years at risk, respectively), although this trend was reversed among Indigenous patients (29.6 compared with 13.2 per 1000 person-years at risk). Hospital mortality was greatest among patients from major cities (8.1%), lower for regional and very remote patients (7.2%), and lowest among remote patients (6.3%). After adjustment for major confounders, there was a mortality benefit associated with increasing remoteness. Compared with patients from major cities, mortality odds ratios (95% confidence intervals) were 0.87 (0.85-0.89) for inner regional, 0.83 (0.81-0.86) for outer regional, 0.75 (0.69-0.81) for remote, and 0.71 (0.65-0.78) for very remote patients. This effect was most marked among Indigenous patients, those with chronic illnesses, higher risk diagnoses, and emergency admissions.
CONCLUSION: Remoteness of residence is associated with higher rates of ICU admission and lower odds of hospital mortality. Lower admission rates among remote Indigenous people and reduced odds of death among high-risk patients from remote areas suggest survivor bias driven by prehospital deaths may be contributing. Further studies of prehospital data are warranted.