Outcomes for Māori and European patients admitted to New Zealand intensive care units between 2009 and 2018

To describe characteristics and outcomes of Māori and European patients admitted to New Zealand intensive care units (ICUs) between 2009 and 2018.

A retrospectively designed prospective cohort study. New Zealand Ministry of Health National Minimum Dataset matched to the Australia New Zealand Intensive Care Society Centre for Outcome and Resource Evaluation Adult Patient Database. The primary outcome was day-180 mortality. Secondary outcomes were ICU mortality, hospital mortality, discharge to home, ICU length of stay, hospital length of stay and survival time. We report associations between Māori ethnicity and each outcome, with European as the reference category, using regression analyses to adjust sequentially for site, deprivation status, sex, year of admission, the Charlson comorbidity index, age, admission source and type, ICU admission diagnosis, ventilation status and illness severity based on physiological parameters.

Māori admitted to ICU were on average 13 years younger than European patients. A total of 968 of 9,681 (10%) Māori and 2,732 of 42,871 (5.2%) European patients were admitted after trauma, and 740 of 9,681 (7.6%) and 2,318 of 42,871 (4.4%) were admitted with sepsis respectively. A total of 1,550 of 9,681 (16.0%) Māori and 6,407 of 42,871 (14.9%) European patients died within 180 days of ICU admission; odds ratio (OR) 1.08; 95% CI, 1.02 to 1.15. When adjusted for age, the OR for day-180 mortality for Māori versus European patients increased substantially. The OR decreased after adjustment for admission source and type, and after accounting for Māori having a higher comorbidity index and more severe illness than European patients. In the final model, incorporating adjustment for all specified variables, Māori ethnicity was not associated with day-180 mortality (adjusted OR 1.01; 95%CI, 0.92 to 1.10). Findings were similar for all secondary outcomes.

Compared to European patients, Māori were markedly more likely to be admitted to the ICU after trauma or with sepsis. Despite Māori being on average 13 years younger at ICU admission than their European counterparts, they had more co-morbidities, higher illness severity and a higher risk of dying within 180 days.