Mortality Trends Across Key Diagnostic Groups in Australian and New Zealand ICUs Over the Past 30 Years

The Australia and New Zealand Intensive Care Society (ANZICS) Adult Patient Database (APD) has been operational for 3 decades. It is important to understand how mortality outcomes have changed across diagnostic groups over time to facilitate the planning of future healthcare resources. We evaluated the trends in risk-adjusted mortality for ICU patients over the last 30 years.

A retrospective cohort study.

All ICUs in Australia and New Zealand that contributed data to the ANZICS APD from January 1993 to December 2022.

Adult patients (≥ 16 yr) admitted to Australian and New Zealand ICUs.

None.

The final cohort included 2,838,654 patients from 209 ICUs. Compared with the first decade patients admitted during the final decade of the study were older (60.0 yr [18.2 yr] vs. 62.0 yr [17.8 yr]), more often had a least one major comorbidity (23.2% vs. 25.2%), and had higher Acute Physiology and Chronic Health Evaluation III scores (45.6 [28.1] vs. 50.9 [24.1]). The five diagnostic groups with the highest mortality rates were cardiac arrest (53.6%), stroke and intracranial hemorrhage (34.8%), subarachnoid hemorrhage (21.2%), pneumonia (19.2%), and sepsis (19%). Risk-adjusted mortality decreased until 2010 but then plateaued. Cardiac arrest saw the greatest improvement in risk-adjusted mortality between the third vs. first study decades (odds ratio [OR], 0.82 [0.81-0.83]), while pneumonia saw the least (OR, 0.87 [0.87-0.88]). The pattern of improvement for most diagnostic groups were similar; however, mortality from stroke and intracranial hemorrhage continued to improve, whereas mortality from cardiac arrest appears to have increased over the past 10 years.

There have been substantial improvements in risk-adjusted mortality among ICU patients over the past 30 years; however, this improvement has plateaued recently. The reasons for this plateau warrant further investigation.